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[Display omitted] • Lupin-stabilized droplets contribute to structure of heat-induced whey protein gels. • Gel microstructure can be modified by addition of lupin or whey emulsions. • Increasing lupin concentration at the interface formed softer gels and led to flocculation. • Lupin-stabilized droplets interact via non-covalent forces with whey protein matrix. This work aimed to understand the role of lupin protein or mixed lupin-whey protein stabilized oil droplets on the texture and microstructure of a heat-induced whey protein gel. Protein-stabilized emulsions were compared to surfactant-stabilized emulsions to investigate the potential of their interfacial interactions to impart unique structures in the filled gels. The structure development was followed in situ using rheology and the final heat-induced gels were characterized by small and large amplitude oscillatory rheology and confocal microscopy. The development of the gel modulus as well as the final gel properties were linked to the type of interactions between the whey protein matrix and the protein adsorbed at the oil interface. The final gels were selectively dissolved in various buffers, and the results showed that replacing interfacial whey protein with lupin protein resulted in a reduced amount of disulfide bridges, explaining the softer gel in the lupin containing gels compared to those with whey protein. Non-covalent interactions were the main forces involved in the formation of actively filled droplets in the gel network. This work demonstrated that by modulating the interfacial composition of the oil droplets, differing gel structures could be achieved due to differences in the protein–protein interactions between the continuous and the interfacial phase. There is therefore potential for the development of innovative products using lupin-whey protein mixtures, by careful control of the processing steps and the matrix composition. [ABSTRACT FROM AUTHOR]

There has been increasing interest in understanding how to utilize plant proteins for foods. In this study, the adsorption dynamics and emulsifying properties of lupin proteins were studied, in isolation and in combination with whey proteins, to evaluate potential synergies occurring at the interface. Analysis of the viscoelastic properties of lupin-whey protein interfaces demonstrated that lupin proteins are highly surface active compared to whey proteins, particularly the most soluble lupin proteins. Furthermore, in the mixed systems, the elastic and viscous properties of the interfaces differed depending on the order of protein addition. The interfacial structures were also probed by studying displacement by surfactant. Emulsions prepared with both lupin and whey proteins showed reduced bridging flocculation when compared to lupin-only stabilized emulsions. Emulsions stabilized with whey proteins only, on the other hand, did not show any bridging flocculation. The creaming stability of bulk emulsions was also dependent on the order of protein addition. Transmission electron microscopy images confirmed the presence of aggregates when lupin protein isolate was employed as the main emulsifier. This work highlights the potential benefits of using protein blends to control the emulsion properties by altering the order and point of protein addition during processing. [Display omitted] • Lupin protein (LPI) shows comparable emulsifying properties to whey protein (WPI). • Colloidal aggregates in LPI lead to emulsion flocculation. • Order of protein addition (LPI or WPI) affects final emulsion properties. • LPI and WPI differ in susceptibility to displacement from oil-water interface. [ABSTRACT FROM AUTHOR]

In organic egg production it is required that the hens have access to pasture or forage material, which offers a wide range of various plant material. In the temperate climate, grasses, herbs and legumes are cultivated in the pasture for the hens, or the forage material may be fed as silage or dried. The effects of grasses and herbs consumed by the egg laying hen on the egg quality parameters of fatty acid composition, yolk colour and carotenoid content, and the sensory properties are elucidated. Forage material of grasses and herbs typically affects the egg yolk fatty acid composition towards a relative higher content of polyunsaturated fatty acids and in particular n-3 fatty acids, which decreases the ratio of n-6/n-3 from 11 to 19 in eggs from hens without access to pasture or forage material to ~5 in eggs from hens on grass pasture. The egg yolk colour is highly affected by plant material type and intake of the hen, where different carotenoids of different herbs are reflected in the yolk carotenoids. Pastures of grass, alfalfa silage and stinging nettle are plant sources with high potential of affecting the egg yolk to a more reddish and yellow colour. Sensory properties of eggs from hens fed forage material or on pasture appear to be affected in some experiments, however, not as a general result. The amount of intake of the forage materials is essential for its impact on the egg quality, and the presently reported intakes span from 6 g/hen/day to 126 g/hen/day, which depend on both the forage material as well as the hen. In summary, the egg quality parameters of fatty acid composition and yolk colour are highly affected by grass and herbs, whereas the sensory properties are less predictable to reflect the grass and herb intake by organic egg layers. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate mussel meal and starfish meals as protein sources for organic layers by studying the effect on production performance, nutrient digestibility and egg quality. A total of 300 Hisex white laying hens (20-week old) were distributed randomly to 6 dietary treatment groups, each with five replicates, including a control diet providing fish meal, 3 diets providing mussel meal (4, 8 and 12 g/100 g) and 2 diets providing starfish meal (4 and 8 g/100 g). Laying rate, egg mass, feed conversion ratio, mortality and live weight of the hens did not differ among treatments. The egg weight was not different from the egg weights of control diets, but the inclusion of 4 g mussel meal resulted in a lower ( P < 0.05) egg weight than 8 g and 12 g mussel meal per 100 g feed. The egg shell strength was not affected by any of the diets. The egg yolk colour was lower ( P < 0.05) in lightness (L*) and higher ( P < 0.05) in redness (a*) for each increase in mussel meal concentration, but was not affected by starfish meal. The albumen dry matter content was not significantly different among diets, whereas the albumen gel fracture stress was lower ( P < 0.05) in eggs from hens fed 4 g mussel meal/100 g diet compared to the starfish diets. Eggs from hens fed 12 g mussel meal/100 g diet showed a fishy smell in the sensory evaluations. The retention of nitrogen was significantly higher in hens receiving 12 g mussel meal and 8 g starfish meal than in control hens ( P < 0.05). Increasing the dietary mussel meal concentrations increased the total tract nitrogen corrected apparent metabolisable energy (AMEn) ( P < 0.001). Diets with 8 g and 12 g mussel meal/100 g diet showed the highest apparent metabolisable energy, whereas the lowest was observed in diets providing 4 and 8 g starfish meals/100 g. The apparent total tract amino acid digestibility was higher ( P < 0.05) in the diets with 8 and 12 g mussel meal and 4 g starfish meal compared with the control diet. Compared to the control diet, the apparent digestibility of methionine was higher ( P < 0.05) in hens fed with 8 and 12 g mussel meal, and the apparent digestibility of lysine was higher in hens fed 4, 8 and 12 g mussel meal and 4 g starfish meal/100 g diet. Fat digestibility was higher ( P < 0.05) in diets with 4, 8 and 12 g mussel meal compared with the control diet. In conclusion, up to 8 g mussel meal and starfish meal per 100 g feed can be used in diets as a high quality protein source for egg production. These meals can replace fish meal; however, an inclusion level higher than 8 g/100 g of mussel or starfish meal may result in a fishy smell of the eggs. [ABSTRACT FROM AUTHOR]

In this study, the impact of high intensity ultrasound (HIU) on proteins in whey protein isolates was examined. Effects on thermal behavior, secondary structure and nature of intra- and intermolecular bonds during heat-induced gelling were investigated. Ultrasonication (24 kHz, 300 W/cm 2 , 2078 J/mL) significantly reduced denaturation enthalpies, whereas no change in secondary structure was detected by circular dichroism. The thiol-blocking agent N-ethylmaleimide was applied in order to inhibit formation of disulfide bonds during gel formation. Results showed that increased contents of α-lactalbumin (α-La) were associated with increased sensitivity to ultrasonication. The α-La:β-lactoglobulin (β-Lg) ratio greatly affected the nature of the interactions formed during gelation, where higher amounts of α-La lead to a gel more dependent on disulfide bonds. These results contribute to clarifying the mechanisms mediating the effects of HIU on whey proteins on the molecular level, thus moving further toward implementing HIU in the processing chain in the food industry. [ABSTRACT FROM AUTHOR]

Acidic whey protein isolate (WPI) dispersions are widely applied for translucent whey-based beverages. However, developing beverages that maintain clarity during extended storage can be a challenge. The formation of visible aggregates occurs recurrently during storage, leading to reduced consumer satisfaction. Batch-to-batch variation with respect to the degree of aggregation also is observed, which impairs shelf-life determination. In this study, two WPI batches (A and B) with different levels of visible aggregate formation during the storage of acidic dispersions were analyzed. Visual evaluations, oscillatory rheology, and absorbance measurements (A500) were applied to assess the formation of visible aggregates in 70 g protein L −1 WPI dispersions during a 6-month period. It was shown, that by changing the heat treatment from the conventional conditions of 95 °C for 180 s to 120 °C for 20 s and/or lowering the storage temperature from the conventional 20 °C–4 °C, the formation of visible aggregates was prevented over the 6-month storage period. The protein composition of the aggregates and the surrounding clear liquid was analyzed by 2-dimensional gel-electrophoreses. The visible aggregate was highly enriched by a low pI spot, possibly containing caseinomacropeptide and/or proteolytically truncated fragments of β-lactoglobulin and α-lactalbumin. [ABSTRACT FROM AUTHOR]

The development of coagulation properties during cold storage of raw milks categorized as good or poorly coagulating is largely unknown. This was studied in the present investigation at individual cow's milk level in addition to elucidating the impact of cheesemaking processing steps on the resulting coagulation properties of silo tank cheesemilk. Rennet coagulation time (RCT), curd firming rate (CFR) and gel firmness (G'max); Ca, P and Mg distribution; pH; and casein micelle size of raw skim milk from individual cows classified as 'good' or 'poor' in coagulation properties were investigated over 72 h storage at 4 °C. For the cheesemilk, the impact of overnight cold storage, thermization and standardization, pasteurization, and acidification to either pH 6.45 or 6.30 on the coagulation properties were studied. After 24 h of cold storage, RCT of both good and poorly coagulating milks was significantly prolonged though recovering somewhat after prolonged storage for good coagulating samples. In contrast, G'max was significantly reduced after 72 h of cold storage for good coagulating milk. Both total and colloidal Ca were higher in good compared with poorly coagulating milk, while mineral distribution and milk pH did not change during storage. For cheesemilk, up to 14 h, cold storage did not impair coagulation properties significantly, which was markedly improved by acidification. The study shows that rheological parameters of good and poorly coagulating milks are impacted differently by the cold storage. Conversely, cheesemilk coagulation properties were not impaired by the studied cheesemaking processing steps and, further, were enhanced by acidification steps. [ABSTRACT FROM AUTHOR]

Inthis study, immediate and long-term effects of high intensity ultrasoundon crystallization mechanisms of anhydrous milk fat were examined.Short time (5 s) ultrasound treatment (24 kHz, 300 W/cm2, 17.5 J/mL) of milk fat induced crystallization onset at highertemperatures and a longer temperature interval between the crystallizationof the high and low melting fractions. The solid fat content in ultrasonicatedmilk fat was higher during cooling to 5 °C and for the first20 min of incubation at this temperature. After 20 min, the increasediminished, and during further storage, the solid fat content in theultrasonicated fat remained lower than in the nontreated fat. Ultrasoundtreatment promoted the formation of spherulite structures and a highdegree of size uniformity. Nano- and microscopic changes lead to alteredmacroscopic properties, where a softer and less brittle milk fat materialwas obtained, and the effects were sustained during storage. Theseresults contribute to clarify the mechanisms underlying the effectsof ultrasound treatment on fat crystallization and shed light on thepotential use of ultrasound in the processing chain to tailor productswith desired textural properties. [ABSTRACT FROM AUTHOR]

The paper describes a study on the variation of coagulation properties in individual cow's milk measured by a novel free oscillation rheometry-based method. The work is part of a study on the occurrence and underlying causes of poorly and even non-coagulating (NC) milk in Denmark, and based on that, the paper reports on the frequency of non- and poorly coagulating milk in a herd of the three main Danish dairy breeds, Jersey, Danish red (RDM), and Danish Holstein-Friesian (SDM). The cows were milked by automatic milking. The rennet coagulation time, the coagulum firmness by storage modulus G′, and the curd firming rate of fresh skimmed milk were determined. More than 20% of the milk samples exhibited poor coagulation properties by the criteria set. Of these, the 17% resulted in a weak coagulum after addition of rennet, while another 3% were due to NC milk that did not aggregate to form a curd within the 40 min of measurement. Milk from Jersey cows exhibited superior coagulation properties when compared to milk from SDM and RDM cows. The dependence of curd firming rate on protein concentration was investigated, and found to depend on milk protein concentration to the power of three, emphasizing the importance of protein interactions, and not just the protein concentration itself. The paper gives a basis for the subsequent selection of NC milk samples with the aim to look in more detail for the underlying reasons for the phenomenon of NC milk. [ABSTRACT FROM AUTHOR]

The paper describes a study on the variation of coagulation properties in individual cow's milk measured by a novel free oscillation rheometry-based method. The work is part of a study on the occurrence and underlying causes of poorly and even non-coagulating (NC) milk in Denmark, and based on that, the paper reports on the frequency of non- and poorly coagulating milk in a herd of the three main Danish dairy breeds, Jersey, Danish red (RDM), and Danish Holstein-Friesian (SDM). The cows were milked by automatic milking. The rennet coagulation time, the coagulum firmness by storage modulus G′, and the curd firming rate of fresh skimmed milk were determined. More than 20% of the milk samples exhibited poor coagulation properties by the criteria set. Of these, the 17% resulted in a weak coagulum after addition of rennet, while another 3% were due to NC milk that did not aggregate to form a curd within the 40 min of measurement. Milk from Jersey cows exhibited superior coagulation properties when compared to milk from SDM and RDM cows. The dependence of curd firming rate on protein concentration was investigated, and found to depend on milk protein concentration to the power of three, emphasizing the importance of protein interactions, and not just the protein concentration itself. The paper gives a basis for the subsequent selection of NC milk samples with the aim to look in more detail for the underlying reasons for the phenomenon of NC milk. [ABSTRACT FROM AUTHOR]

Direct heat treatment of two milk types, skimmed and nonstandardised full-fat, was performed by instant steam infusion and compared with indirect heating. Infusion conditions were temperatures of 72–120°C combined with holding times of 100–700 ms, and indirect heat conditions were 72°C/15 s and 85°C/30 s. The activity of indigenous enzymes such as alkaline phosphatase, lactoperoxidase, xanthine oxidase and γ-glutamyl transpeptidase was evaluated. Infusion temperature was the main determinant of inactivation. Whey protein denaturation represented by β-lactoglobulin increased significantly with infusion temperature. The nonstandardised milk had a higher denaturation rate than skimmed milk. The effect of instant infusion on pH and milk fat globule size in relation to whey protein denaturation and association is discussed. [ABSTRACT FROM AUTHOR]

The effects of high intensity ultrasound (HIU) treatment on physical properties of whey protein isolate (WPI) gels, i.e., water holding capacity, gel strength and elasticity, were studied. WPIs with different α-lactalbumin:β-lactoglobulin (α-la:β-lg) ratios were subjected to ultrasonication (24 kHz, 300 W cm −2 , 2078 J mL −1 ) with and without temperature control, i.e., T < 20 °C and T < 65 °C, respectively. Effects of ultrasonication were greatly affected by the relative amount of α-la, most likely due to the type of interactions formed during gelation after ultrasonication. For WPI with relative high α-la content ultrasonication improved the water holding capacity and gel strength of the heat-induced gels. To the contrary, for WPIs with intermediate or low α-la content, no changes in physical properties were observed. These results contribute to clarifying the mechanisms underlying the effects of HIU on WPI, linking effects on protein level to physical properties. [ABSTRACT FROM AUTHOR]

Two types of milk, skim milk and non-standardised raw milk, were heat treated using direct heating by instant infusion pasteurisation with treatment temperatures in the range from 72°C to 120°C and with holding times of less than 1 second. Indirect heating by HTST pasteurisation (72°C for 15 seconds) was used for comparison. The inactivation of microorganisms reached at least the same level when using instant infusion pasteurisation compared to HTST pasteurisation. Changes in the physical-chemical properties were observed in the skim milk fractions of instant infusion pasteurised non-standardised milk, whereas for instant infusion pasteurised skim milk less influence from the treatments was observed. [ABSTRACT FROM AUTHOR]

Abstract: An ovomucin fraction was isolated from egg albumen by isoelectric precipitation, however, of low solubility. To improve solubility, the ovomucin was hydrolysed with four proteases (pronase E, alcalase, flavourzyme, neutrase) for 0–24h. The hydrolysed ovomucin was analysed for degree of hydrolysis (DH), solubility, surface hydrophobicity (S 0), surface tension, and foaming properties: capacity and stability. The solubility of hydrolysed ovomucin increased logarithmically with DH. The pronase E exposed highest activity and neutrase the lowest, which correlated with the effect on ovomucin solubility. Hydrolysis with flavourzyme and neutrase increased the S 0, primarily during 0–6h, but pronase E and alcalase hydrolysis reduced the S 0 compared with the unhydrolysed ovomucin. Foaming capacity reached an optimum at DH of 15–40%, and correlated highly with the initial surface tension drop. Enzymatic hydrolysis did no significantly affect the foam stability. [Copyright &y& Elsevier]

Two experiments were conducted to study the effects of different forage crops on productivity and some egg quality parameters of small flocks of organic laying hens fed whole wheat or concentrates. Each experiment was carried out in a split plot design with two different forage crops and two types of supplementary feed (typical concentrate for organic layers versus whole wheat) with three replications. In the first experiment the tested forage crops were of a well-established grass/clover and a mixture of forbs ( Fagopyrum esculentum, Phacelia tanacetifolia and Linum usitatissimum ). In the second experiment the tested forage crops were a well-established grass/clover and chicory ( Cichorium intybus cv. Grassland Puna). The results on productivity and egg quality suggest that laying hens consume large amounts of foraging material when accessible. In nutrient restricted hens (wheat-fed) the forage may yield a substantial contribution to the requirements of amino acids and metabolizable energy although productivity parameters and measurements on dry matter in albumen showed that wheat-fed hens, on a short-term basis, were not able to fully compensate for the lack of protein and amino acids by increased foraging. Of the forage crops investigated especially chicory seems to contribute to the nutrition of the hens. Measurements on eggshell parameters showed that oyster shells together with foraging material were sufficient to meet the hens’ calcium requirements. Yolk colour clearly revealed that laying hens consume large quantities of green fodder irrespective of the type of supplementary feed. Yolk colour from hens with access to chicory tended to be darker, of a redder and less yellow hue compared with grass/clover fed hens, which is considered a positive quality. [ABSTRACT FROM AUTHOR]

Present pasteurization methods of dried egg albumen powder require large storage facilities and take a long time. The use of a fluidized bed system for dry pasterurization of egg albumen was studied as an alternative approach. In Experiment 1 two different temperature treatments were investigated (90 °C and 130 °C); whilst in Experiment 2 the effect of high vs. low air moisture was studied at a fixed temperature of 115 °C. Both experiments had process times of between 10 min and 3 h. The Reference method was traditional pasteurization at 90 °C for 21 h. Samples were analysed for microbiological, chemical and physical properties. High temperature or high air moisture treatments ensured greater bacterial elimination, formation of covalently bound protein polymers and increased surface hydrophobicity. The nature of polymer bonds is suggested to be Schiff's bases, which increase correspondingly. The powder colour became darker and more yellow at high temperature for 3 h and particle size increased. [ABSTRACT FROM AUTHOR]

Dry-pasteurization of egg albumen (EA) powder in a fluidized bed was studied in two experiments. Experiment 1 consisted of two different temperatures (90 and 130 °C) and experiment 2 of two air moisture levels (high and low). Powders were processed from 10 min to 3 h. The reference treatment was traditional pasteurization at 90 °C for 21 h. The fluidized bed treatment effects on gel texture, water-holding capacity (WHC), protein binding, gel colour, foaming capacity, foam stability and surface pressure were evaluated. Gels of EA powders treated at high temperature and high air moisture levels exhibited higher stress, strain and WHC values than gels of untreated EA powder. The gel colour became significantly darker, greener and less yellow by fluidized bed treatment. Foaming and surface activity properties were un-affected by the treatments, however, foam stability against liquid drainage correlated positively with surface pressure. [ABSTRACT FROM AUTHOR]

Spore forming microorganisms pose significant challenges in the food industry, contributing to spoilage and foodborne illnesses. Despite the unfavourable pH conditions of acid foods, certain acid-resistant spore forming bacteria and moulds have shown their capacity to grow, and thereby posing quality and safety concerns. This review discusses our current knowledge of different spore forming bacteria, including Alicyclobacillus spp., Bacillus spp., and Clostridium spp., as well as ascospore producing moulds such as Byssochlamys spp., Neosartorya spp., and Talaromyces spp., involved in the spoilage of various acid food products. The main concerning attribute increasing the spoilage risk of these microorganisms, together with their acid resistance, is their resistance to heat, a primary preservation method employed in shelf stable acid foods. Therefore, particular emphasis has been given to the heat resistance of those spore formers. This review consolidates diverse research findings on the heat resistance of spores/ascospores derived from these spoilage microorganisms. It highlights the complexity of inactivation kinetics influenced by spore associated and heating-medium associated factors. Moreover, how certain spoilage spore formers might raise food safety concerns by creating conductive environments for pathogens in acid foods is being discussed. The lack of knowledge on the spoilage potential and heat resistance of certain spore formers in acid foods, as well as the need for future research to identify the potential spoilage risk of spore formers in novel acid foods, are also highlighted. Overall, this review highlights the challenges posed by spore forming bacteria and moulds in acid foods, shedding light on their heat resistance, spoilage potential, and implications for food quality and safety. [ABSTRACT FROM AUTHOR]

The effect on egg quality of reducing the dietary protein and methionine+cystine (experiment 1) and methionine+cystine, lysine and protein (experiment 2) for laying hens with increasing age was studied. In experiment 1, four groups of laying hens were fed different diets in one to three feeding-phases as follows, with protein and methionine+cystine, respectively, in g/10 MJ ME. Group A: 146 and 6.6 at 20-35 weeks (LP1), 136 and 6.0 at 36-74 weeks (LP2). Group B: 156 and 6.6 at 20-35 weeks (K1), 148 and 6.0 at 36-45 weeks (K2), 121 and 4.8 at 46-74 weeks (LP3). Group C: K1 at 20-35 weeks, K2 at 36-74 weeks. Group D: LP1 at 20-74 weeks. In experiment 2, two hen lines (Lohmann Brown and ISA Brown) were fed diets with the following contents of methionine+cystine, lysine and protein, respectively, in g/10 MJ ME. Group A: 4.5, 5.3 and 120 at 21-71 weeks (N). Group B: 5.0, 5.8 and 132 at 21-35 weeks (N10), N at 36-71 weeks. Group C: 5.4, 6.4 and 144 at 21-35 weeks (N20), N10 at 36-45 weeks, N at 46-71 weeks. Group D: 5.9, 6.9 and 156 at 21-35 weeks (N30), N20 at 36-45 weeks, N10 at 46-71 weeks. Egg production and feed intake were registered, and the diets were analysed for nutritional composition. Eggs were collected in each phase for each group for quality analysis, including egg weight, shell weight, shell percentage, albumen height, Haugh unit and shell colour. In experiment 1, no differences in production traits between the groups were observed. In phase 3, group B had an overall lower egg weight, but increased albumen height. In experiment 2, group D had the highest egg output. The egg weight increased and shell percentage and albumen quality decreased with increasing dietary amino acid and protein content, a situation which was especially evident in the first phase at 21-35 weeks of age. [ABSTRACT FROM AUTHOR]

This work investigates the rheological properties of lupin-whey emulsion-filled gels (EFGs) formed using a pilot scale plate heat exchanger. Samples were prepared with either lupin, whey, or a lupin-whey stabilized emulsion, mixed in a whey protein continuous phase. While whey protein in the continuous phase was mainly responsible for the formation of a primary gel network, differences were observed depending on the droplet-whey protein matrix interactions. Full or partial replacement of interfacial proteins with lupin proteins resulted in softer, more ductile gels. Amplitude sweeps showed that the structure was not only affected by the interactions between the droplets and the continuous network, but also by the droplet distribution within the matrix. This work demonstrates the importance of fine tuning the interactions and the distribution of oil droplets within the gel, as these properties will lead to structural heterogeneity at the micro-scale, causing profound differences in the rheological properties. Finally, continuous heating led to stiffer, more particulate gels compared to quiescent conditions, but similar mechanisms underpinned gel formation. Thus, it is demonstrated that the design of the interactions can be screened using an in situ rheometer, although the rheological properties are affected by the shear effect of the plate heat exchanger. • The interfacial protein composition impacts the microstructure and texture of EFGs. • The addition of lupin to the interface results in softer, more deformable gels. • Also affecting the gel heterogeneity and droplet distribution. • Heating in plate heat exchanger forms stiffer gels compared to quiescent heating. [ABSTRACT FROM AUTHOR]

[Display omitted] Plant protein ingredients from similar sources can vary in functionality not only because of compositional differences, but also because of differences in their structure depending on their processing history. It is essential to understand these distinctions to develop novel food emulsion using plant proteins. It is hypothesized that differing interfacial properties can be attributed to their structures, aggregation, and colloidal states. The adsorption behavior of a commercial protein isolate, homogenized or non-homogenized, was compared to a mildly extracted isolate to evaluate the effect of aggregation state and structural differences. After characterization of the particle size and protein composition, the interfacial properties were compared. Atomic force microscopy provided evidence of interfaces packed with protein oligomers regardless of the treatment. Differences in adsorption kinetics and interfacial shear rheology depending on oil polarity suggested different interfacial structures. A polydisperse mixture of protein oligomers resulted in increased rearrangements and protein-protein interactions at the interface. Homogenization of commercial proteins resulted in a lower interfacial tension and less elastic interfaces compared to those of native proteins due to the presence of larger aggregates. This study highlights how the interfacial properties can be related to the protein aggregation state resulting from differences in processing history. [ABSTRACT FROM AUTHOR]

Abstract Ultrasonic homogenization of full fat milk is known to provide changes in the acid-induced gelation behavior, in terms of acceleration of gel formation and increased gel strength. In this study, the dependency of this behavior on ultrasonic power level and treatment temperature was illustrated using an ultrasonic flow cell system, which minimizes temperature increase during treatment. Gel formation was studied by acidification with glucone-δ-lactone at 30 °C using small deformation rheology and effects of ultrasonication on whey protein denaturation, milk fat globule size distribution and proteins associated with the milk fat globule membrane were evaluated. Results illustrate how increased acid-gel strength upon ultrasonication, partly, was attributed to denaturation of whey proteins, but also indicate that changes in the milk fat globule membrane, in terms of increased association of caseins with the milk fat globule membrane, can be of importance by facilitating the formation of highly functional milk fat globule/protein complexes. Highlights • Ultrasound treatment of milk changes the acid-induced gelation behavior. • Temperature and power level was shown to be of importance. • Effects was linked to denaturation and shift in milk fat globule membrane proteins. [ABSTRACT FROM AUTHOR]

Spray dried potato protein and specific isolated fractions were used for foaming and emulsification studies. The spray dried protein was separated into a patatin and a protease inhibitor (PI) rich fraction by ion exchange chromatography (IEX), respectively, and these two fractions were purified by hydrophobic interaction chromatography into a low (HIC 1) and a high (HIC 2) hydrophobic fraction. Foam overrun for the spray dried powder and all patatin fractions were highest at pH 3, with gradually lower values at pH 5 and 7, while the PI fractions had highest overrun at pH 5 and equally lower values at pH 3 and 7. Relative foam stability varied from 18 to 78% of the initial foam at pH 3 while lower variation of 67–80% was seen at pH 5 and 7. The HIC fractions did generally perform better than the spray dried powder and IEX fractions, with patatin HIC 1 and HIC 2 having superior performance at pH 3 and PI HIC 2 at pH 5 and 7. Emulsions were characterized by emulsion stability and activity, emulsion droplet size and small scale dynamic rheological measurements. The PI, and especially PI HIC 1 showed poor emulsion properties with low stability, large droplet size and less texture. Interestingly, PI HIC 2 had much better emulsion properties on par with the spray dried powder and patatin, while having a more frequency dependent textural response. Overall, the best emulsion properties were obtained with patatin HIC 2, thus showing the importance of hydrophobicity for protein functionality. [ABSTRACT FROM AUTHOR]

The objective was to prepare sheared gels of potato protein concentrate and evaluate the effect of pH (3, ∼4, ∼7), ionic strength (15 or 200 mM) and protein drying conditions (spray or freeze drying) on the final appearance and rheological characteristics. Heat-set gels 3 % (w/w) at a high ionic strength (200 mM) resulted in an inhomogeneous appearance with presence of clots, while low ionic strength (15 mM) gave homogenous structures. Gels prepared at pH 3 became transparent while preparation above pH 3.0 resulted in high turbidity. Heat treatment and cooling resulted in gelation for all samples except freeze dried powder at pH 3.0. Flow curves during shear from 0.1 to 100 s−1 were fitted by the Herschel-Bulkley model indicating shear thinning behavior for all samples except the freeze dried sample at pH 3 which displayed a Newtonian behavior. Oscillatory measurements after shear indicated viscus behavior (phase angle above 45°) for the spray dried sample at pH 3, and gelled behavior (phase angle above 45°) for the remaining gelled samples. Structure recovery was observed after shear in all samples except at pH 3.0. The data shows potato protein can be used as ingredient in protein beverages. [ABSTRACT FROM AUTHOR]

This study demonstrates a strong interaction between triacylglycerol (TAG) composition and effects of shear rate on the microstructure and texture of fats. Cocoa butter alternatives with similar saturated fat content, but different major TAGs (PPO-, PSO-, SSO-, POP- and SOS-rich blends) were evaluated. Results show how shear can create a harder texture in fat blends based on symmetric monounsaturated TAGs (up to ∼200%), primarily due to reduction in crystal size, whereas shear has little effect on hardness of asymmetric monounsaturated TAGs. Such differences could not be ascribed to differences in the degree of supercooling, but was found to be a consequence of differences in the crystallisation behaviour of different TAGs. The fractal dimension was evaluated by dimensional detrended fluctuation analysis and Fourier transformation of microscopy images. However, the concept of fractal patterns was found to be insufficient to describe microstructural changes of fat blends with high solid fat content. [ABSTRACT FROM AUTHOR]

This study investigated the effects of Lenient Steam Injection (LSI) treatment at temperatures 70-150 °C on the enzymatic activities of the indigenous milk enzymes alkaline phosphatase, lactoperoxidase (LPO), xanthine oxidase (XO), lipoprotein lipase (LPL) and plasmin in comparison with two reference heat treatments of 63 °C for 30 s and of 72 °C for 15 s by indirect heating. Milk fat globule (MFG) size distributions and pH were also monitored. Alkaline phosphatase, LPO, XO and LPL activities decreased with increasing LSI temperature. Plasmin activity was increased at temperatures <80 °C and decreased at temperatures above 90 °C. Milk fat globule homogenisation was observed at temperatures above 110-130 °C. [ABSTRACT FROM AUTHOR]

The effect of proteolysis on oxidation in low-fat cheese was investigated. The accumulation of dityrosine during storage increased significantly in the cheese with a high degree of proteolysis, while hexanal and heptanal were lower in the cheese with high proteolytic activity, indicating that the peptides/free amino acids acted as antioxidants on the propagating step in lipid oxidation. Dimethyl disulphide concentration was also lower in the cheese with a higher level of peptides. Therefore, oxidation of tyrosine residues seemed to function as antioxidants both regarding secondary lipid oxidation products and protein-derived oxidation products through formation of dityrosine, being a termination reaction. [ABSTRACT FROM AUTHOR]

Summary: The aim of this study was to investigate the mechanisms behind protein–protein interactions in a co‐precipitate of whey protein isolate (WPI) and pea protein isolate (PPI). A co‐precipitate and blend, consisting of 80% WPI and 20% PPI, were compared. Covalent disulphide interactions were studied by blocking of free thiols with N‐Ethylmaleimide (NEM), while electrostatic interactions were studied in systems with 0.5 m NaCl and hydrophobic interactions with 0.2% SDS. Protein solubility, stability and secondary, tertiary and quaternary protein structures were analysed. Co‐precipitation did not introduce different protein–protein interactions than the direct blending of proteins. SDS affected solubility (P < 0.05), secondary and tertiary structure. However, the effects of NEM and NaCl were significant greater (P < 0.05) on the same parameters and thermal stability, especially when combined (P < 0.01). Thus, the protein–protein interactions in a whey–pea co‐precipitate and protein blend consisted of disulphide bonds and electrostatic interactions. [ABSTRACT FROM AUTHOR]

Green macroalgae of the Ulva genus have gained interest as a source of protein, due to the high production potential and high proportion of essential amino acids. This review gives an overview of Ulva protein, including extraction and evaluation of protein quality in terms of nutritional value, functionality, and sensory properties with preliminary suggestions to reach the market. Available literature on protein extraction from Ulva was reviewed along with studies investigating the nutritional quality of Ulva protein and functional properties including aroma and flavor characteristics. Opportunities, challenges, and knowledge gaps are presented. A range of studies are investigating protein extraction, but only a few studies have dealt with protein digestibility, and food protein products. The digestibility of protein in crude Ulva biomass is low compared to conventional protein sources but increase with protein extraction. Sensory and functionality studies on Ulva protein are yet absent, but the whole biomass has been investigated, indicating the potential. The lack of consisting studies calls for more investigations related to food quality of Ulva protein. Upscaling and biorefinery models need to be explored to unfold the true potential of Ulva as a source of food protein. • The green macroalgae Ulva is gaining interest as an alternative protein source. • Protein extraction increases the protein digestibility of Ulva. • Ulva provides a promising amino acid profile, which should be exploited. • Research is needed on the functional and sensory properties of Ulva protein. • A biorefinery model is needed to make Ulva protein economical feasible. [ABSTRACT FROM AUTHOR]

Summary: The aim was to optimise the yield of co‐precipitation of whey protein isolate (WPI) and pea protein isolate (PPI) and compare co‐precipitates and protein blends with respect to solubility. The yield of co‐precipitates was tested with different protein ratios of WPI and PPI in combination with different temperatures and acid precipitation (pH 4.6). The highest precipitation yield was obtained at protein ratios WPI < PPI, high temperature and alkaline protein solvation. The solubility was measured by an instability index and absorption spectroscopy of re‐suspended precipitated proteins at pH 3, 7 and 11.5. Co‐precipitates had significantly lower solubility than protein blends. Protein ratios WPI > PPI, low precipitation temperature and high pH showed the highest solubility. Differences in protein composition between co‐precipitates and protein blends were observed with SDS‐PAGE and matrix‐assisted laser desorption ionisation time‐of‐flight, and indicated different protein–protein interaction in samples, which needs further investigations. [ABSTRACT FROM AUTHOR]

[Display omitted] • A combination of microscopy methods provided insight into the microstructure. • Emulsifying starch changed the microstructure. • Emulsifying starch increased the hardness at 7 % and 9 % protein content. • Effects of prehydration could not be detected macrostructurally. When casein is replaced with starch in imitation cheese, the functionality changes. Three different microscopy methods were applied to understand the microstructural differences in the product depending on which component dominates the microstructure. Confocal Laser Scanning Microscopy (CLSM) for component identification. Scanning Electron Microscopy (SEM) and Cryogenic Scanning Electron Microscopy (Cryo-SEM) for studying surface structures. Differences in the surface structures were detected between SEM and Cryo-SEM. In SEM, starch appeared rough and protein smooth, while in Cryo-SEM no starch roughness of the surface was found. A change in starch modification and effects of protein prehydration was also analysed. Adding octenyl succinic anhydride (OSA) modified starch for emulsifying properties resulted in a microstructure with fragmented protein at a protein level of 7 %, but not at 9 or 12 %. Protein prehydration had limited effect on microstructure. On a macrostructural level, the change to an emulsifying starch increased hardness in imitation cheese with 7 and 9 % protein. Protein prehydration slightly decreased the hardness, but the difference was not significant at all concentrations. This research provides valuable information about the microstructure of imitation cheese at a 50/50 composition, how the microstructure changes with an emulsifying starch and what occurs after a protein prehydration was included in the production. [ABSTRACT FROM AUTHOR]

Controlling viscosity of concentrated protein solutions is an integral part of dairy powder production. Hydrodynamic cavitation has been suggested as a new processing tool for reducing the viscosity of concentrates prior to spray drying. The aim of this study was to evaluate the viscosity reduction of whey protein concentrate as result of hydrodynamic cavitation. A whey protein concentrate (31% dry matter) was subjected to different hydrodynamic cavitation treatments and the viscosity was monitored during 14 days of storage, denaturation enthalpy was evaluated by differential scanning calorimetry and particle size by dynamic light scattering. Results showed that hydrodynamic cavitation treatment decreased viscosity by 7–8%, and this effect remained constant during the 14 days of storage. Based on the analysis of particle size distribution, the viscosity reduction was suggested to be linked to a reduction in the presence of large particles, possibly due to disruption of aggregates. [ABSTRACT FROM AUTHOR]

Summary: Norbixin, a carotenoid extracted from the seeds of the annatto (Bixa orellana) plant, can be used in aqueous food applications, where other carotenoids are too hydrophobic to solubilise in a water environment. The aim of this work was to investigate the effect of pH, antioxidants and transition metal ions with and without hydrogen peroxide (H2O2) on the stability of norbixin in aqueous solutions as well as determining the interaction between these factors and light. The stability of norbixin in buffered aqueous solution stored in light or in the dark was evaluated using absorbance spectrophotometry. Light, reduced pH and metal ions both with and without H2O2 increased the bleaching of norbixin, whereas chelators and the natural antioxidants, ascorbic acid and tocopherol, reduced the bleaching of norbixin. Light significantly increased the loss of norbixin alone and in combination with the other factors. [ABSTRACT FROM AUTHOR]

In this study, the impact of high intensity ultrasound (HIU) treatment on anhydrous milk fat and milk fat/rapeseed oil blends with 10–30 w/w% rapeseed oil is examined. Effects of HIU treatment on crystallization kinetics, thermal behavior, microstructure, texture, and oxidation are evaluated. HIU treatment results in an acceleration of the crystallization process, especially for blends with a high rapeseed oil content. HIU treatment reduces the crystal size, however, HIU treatment does not have any significant effects on the melting behavior or hardness. No significant effects of HIU treatment on secondary oxidation products are observed, indicating that lipid oxidation is not facilitated by the HIU treatment. Practical Application: A great potential exists for the use of use of high intensity ultrasound in the food industry to obtain a shorter and more controllable fat crystallization process. Results from this demonstrate how the impact of ultrasound treatment is affected by diluting a hard fat with liquid oil. Such effects are of great importance in, for instance, the dairy industry, where high intensity ultrasound potentially provides an additional processing tool in the production of spreadable blends based on milk fat and rapeseed oil. Ultrasound treatment is introduced in a circulating flow system, a more realistic representation of an industrial setting compared with commonly used probe based bath systems. High intensity ultrasound accelerates the crystallization kinetics of anhydrous milk fat and rapeseed oil blends, resulting in the formation of smaller crystals but no differences in melting properties or hardness. This is obtained in a circulating flow cell, without detection of increased levels of secondary oxidation products. High intensity ultrasound accelerates the crystallization kinetics of anhydrous milk fat and rapeseed oil blends, resulting in the formation of smaller crystals but no differences in melting properties or hardness. This is obtained in a circulating flow cell, without detection of increased levels of secondary oxidation products. [ABSTRACT FROM AUTHOR]

The current study investigated the effects of fishmeal quality (low (LB) and high (HB) levels of endogenous biogenic amines) and feed extrusion temperatures (100 and 130 °C) on protein oxidation indicators and amino acids racemization (AAR) in extruded fish feed. Furthermore, the study investigated the accompanying effects on feeding the diets to juvenile rainbow trout ( Oncorhynchus mykiss ) on fish growth performance, in vivo amino acids (AAs) digestibility, and liver and plasma metabolites following an 8-week feeding trial. A principal component analysis (PCA) showed that better growth performance, secondary oxidation products, and racemized methionine correlated positively with a low content of biogenic amines, whereas the primary oxidation product, protein hydroperoxides, and in vivo AAs digestibility correlated positively with high content of biogenic amines. At an extrusion temperature of 100 °C, the growth performance of the fish decreased when the content of biogenic amines increased. In contrast, at an extrusion temperature of 130 °C, the growth performance was unaffected by the level of biogenic amines. The latter could be a consequence of the higher level of protein oxidation of LB fishmeal compared to HB fishmeal at this temperature. Higher levels of liver pyruvate and plasma lactate together with high level of betaine and AAs in both liver and plasma were associated with the LB fishmeal diets. The lower concentration of AAs especially in liver of fish fed with HB fishmeal demonstrated that these AAs might not be supplied sufficiently for the tricarboxylic acid cycle to generate energy and therefore a decreased growth was found in fish fed this diet. Furthermore, the results indicated that biogenic amines and feed attractants such as betaine are more decisive for evaluating the quality of fishmeal than protein quality parameters. [ABSTRACT FROM AUTHOR]

The spoilage of acid foods, such as fruit juices and canned fruits and vegetables, caused by spore-forming bacteria has been well studied in literature. However, there is a lack of knowledge on the spoilage potential of spore-forming bacteria in ambient/shelf-stable acid dairy-based products. The present study investigated the germination and growth potential of spores from sixteen different bacterial species commonly present in milk and dairy or non-dairy ingredients. Experimental conditions were selected as relevant to acid dairy-based products (pH 4.6, the presence of 0.4% and 0.8% lactic acid (LA)) when stored at normal (25 °C) and elevated ambient temperatures (40 °C) for a period of 12 weeks. As a consequence of the observed growth, the spore heat resistance of four strains of Alicyclobacillus acidoterrestris was evaluated in a yoghurt-based medium. The growth experiments indicated that the spores of seven bacterial species (A. acidoterrestris , B. megaterium , B. subtilis , B. coagulans , C. beijerinckii , C. butyricum , and C. tyrobutyricum) out of sixteen exhibited the ability to germinate and grow at a pH of 4.6 and temperatures of 25 °C and/or 40 °C. However, none of the spores from 16 bacterial species grew at pH 4.6 in the presence of lactic acid (0.4% and 0.8%) at 25 °C, while only A. acidoterrestris spores grew at 40 °C regardless of the presence of lactic acid in the growth medium. The thermal inactivation kinetics of A. acidoterrestris spores revealed that all four strains possess high thermal resistance profiles in yoghurt-based medium at pH 4.6, indicating that traditional pasteurization treatment may not be sufficiently effective in controlling their growth. This study highlights the significance of A. acidoterrestris as a potential causative agent of spoilage in ambient acid dairy-fruit products at elevated ambient temperatures and the need for further research on effective control measures for this species. • Bacterial spores from seven out of sixteen species were able to grow at pH 4.6 and temperatures of 25 °C and/or 40 °C. • The presence of lactic acid (up to 0.8%) inhibited the growth of spores of all tested species except A. acidoterrestris. • Four A. acidoterrestris strains showed similar and high thermal resistance profiles in an acid yoghurt-based medium. • A. acidoterrestris was identified as a potential causative agent of spoilage in ambient acid dairy-based products. [ABSTRACT FROM AUTHOR]

Reduced NaCl in semi-hard cheeses greatly affects textural and sensory properties. The interaction between cheese NaCl concentration and texture was affected by brining time (0–28 h), dl -starter cultures (C1, C2, and C3), chymosin type (bovine or camel), and ripening time (1–12 weeks). Cheese NaCl levels ranged from <0.15 to 1.90% (w/w). NaCl distribution changed during ripening; migration from cheese edge to core led to a more homogeneous NaCl distribution after 12 weeks. As ripening time increased, cheese firmness decreased. Cheeses with reduced NaCl were less firm and more compressible. Cheeses produced with C2 were significantly firmer than those produced with C1; cheeses produced with C3 had higher firmness and compressibility. In NaCl reduced cheese, use of camel chymosin as coagulant resulted in significantly higher firmness than that given using bovine chymosin. Overall, cheese NaCl content is reducible without significant textural impact using well-defined starter cultures and camel chymosin. [ABSTRACT FROM AUTHOR]

Formation of insoluble aggregates in acidic whey protein isolate (WPI) beverages during storage is a quality concern. Earlier studies showed that changes in processing methods from 95 °C for 180 s–120 °C for 20 s could prevent it. In the present study, WPI drinks were stored for up to 12 months and insoluble aggregates formed in re-solubilised WPI and its liquid phase analysed by proteomics. Insoluble aggregates were found to be enriched in caseinomacropeptides (CMP). Increased peptide formation by weak acid hydrolysis, especially of CMP, was found at 120 °C. Further enhanced hydrolysis of CMP was obtained by deamidation as well as by the presence of the genetic variant A of CMP. Batch variations may therefore be assigned to variations in CMP as well as variations in the distribution of genetic variants of A and B in different WPI batches used for the production of the WPI products. [ABSTRACT FROM AUTHOR]

This study demonstrates a link between the fat crystal network, fracturing behavior, and sound emission upon breakage. SOS, PSO, PPO, and POP rich fats were characterized by SAXS/WAXS and confocal laser scanning microscopy. Simultaneous texture and acoustic analysis was conducted by the use of a texture analyzer connected with an acoustic envelope detector and augmented by a broad band microphone combined with a digital sampling oscilloscope. Results shows a high correlation between negative values of the 2nd derivative of force curves, providing a measure of the energy release, and the sound intensity ( r = 0.89, p < 0.05). No relation between acoustic properties and polymorphic behavior, crystal size, or crystal morphology was found. All fats crystallized into a β′ form within 1 day of storage. Subsequently, only the PPO and POP rich fats transformed into the β form (2-4 wk). Evaluation of the relative strength of intra- and interparticle links within the fat crystal network, indicate an important role of inter-particle links for the sound intensity, whereas intra-particle links were of less importance. It is hypothesized that strong interparticle links provide a strong rigid structure resulting in build-up of energy during compression and a fast energy release upon breakage accompanied by sound emission. Practical applications: Results from this study provide important knowledge on acoustic properties of fat which can contribute to ensuring a suitable snap, in terms of a high intense sound upon breakage, of chocolate and confectionery products. Acoustic properties of fats are important for the snap of chocolate and confectionery products. This study demonstrates how the breakage sound intensity is significantly correlated with the negative part of the second derivate of force curves, which can be related to a rigid structure due to strong intraparticle links. [ABSTRACT FROM AUTHOR]

Ultrafiltration was applied to diluted potato fruit juice, a side-stream from potato starch production. The aim of the study was to selectively concentrate the potato proteins in the permeate, while isolating polyphenol oxidase (PPO) in the retentate. A profound difference was found in protein retention between two 300-kDa molecular weight cutoff (MWCO) ultrafiltration membranes, of either regenerated cellulose (RC) or polyethersulfone (PES). The use of the 300-kDa MWCO RC membrane resulted in a twofold higher retentate protein content as well as total retention of all PPO activity, as compared with the PES membrane. Comparison tests with 100- and 300-kDa MWCO PES membranes indicated that concentration polarization and gel layer formation, and not MWCO definitions, were governing factors for protein retention, since proteins with a MW of 10 kDa were retained in all the experiments. PPO activity in potato fruit juice was measured in permeate and retentate to assess its selective retention by the applied ultrafiltration processes. Of the specific PPO activity, 94-100 % was retained by either 300 MWCO RC or 100 MWCO PES, while only 49 % specific activity was retained by the 300 MWCO PES. By in situ blotting experiments, the molecular weight of active PPO was found to be present at three different molecular weights, at positions of 40, 47, and 100 kDa, respectively, with the major activity present at 47 kDa. [ABSTRACT FROM AUTHOR]

Reduction of sodium chloride (NaCl) in cheese manufacturing is a challenge for the dairy industry. NaCl has a profound role on microbial development influencing cheese sensory and technological properties. The purpose of this work was to investigate how proliferation, distribution and autolysis of two commercial DL-starter cultures (C1 and C2) used in the production of Danish semi-hard Samsoe cheeses were affected by reduced NaCl levels. Cheeses containing < 0.3% (unsalted), 2.3% (reduced-salt) and 3.4% (normal-salted) (w/v) NaCl in moisture were produced and analyzed during 12 weeks of ripening. Lactic acid bacteria (LAB), distribution of bacteria as single cells or microcolonies, their viability in the cheeses and cell autolysis were monitored during ripening, as well as the impact of NaCl content and autolysis on the formation of free amino acids (FAA). Reduction of NaCl resulted in higher LAB counts at the early stages of ripening, with differences between the two DL-starter cultures. The unsalted cheeses produced with C1 had retained a significantly higher number of the initial LAB counts (cfu/g) after 1 and 2 weeks of ripening (i.e. 58% and 71%), compared to the normal-salted cheeses (i.e. 22% and 21%), whereas no significant difference was found between the reduced-salt (i.e. 31% and 35%) and normal-salted cheeses. At the later stages of ripening (i.e. 7 and 11 weeks) NaCl had no significant influence. For cheeses produced with C2, a significant influence of NaCl was only found in cheeses ripened for 7 weeks, where the unsalted and reduced-salt cheeses had retained a significantly higher number of the initial LAB counts (cfu/g) (i.e. 39% and 38%), compared to the normal-salted cheeses (i.e. 21%). In the Samsoe cheeses, bacteria were organized as single cells, in groups of 2–3 cells or in groups of ≥ 4 cells. During ripening the decrease in the number of viable bacteria was mainly due to a reduction in the number of viable bacteria organized in groups of ≥ 4 cells. A negative correlation between NaCl content and PepX activity was observed. At the end of ripening the total FAA content was lower in the unsalted cheeses, compared to the reduced- and normal-salted cheeses. In conclusion, NaCl had a significant influence on proliferation of both DL-starter cultures. However, the influence of NaCl on culture development was more pronounced in cheeses produced with DL-starter culture C1. As both texture and taste are parameters known to be affected by the development of the starter culture, the design of starter cultures for reduced NaCl cheeses is recommended. [ABSTRACT FROM AUTHOR]

The initial stage of the Maillard reaction, protein lactosylation, occurs during heat treatment of milk and continues during subsequent storage. We compared the initial lactosylation as well as the rate of lactosylation of milk proteins during storage in UHT milk subjected to direct or indirect heat treatment using liquid chromatography ( LC) coupled with electrospray injection mass spectrometry ( ESI- MS). Furosine content was used as an overall marker to allow for a quantitative correlation of lactosylation measured by LC- ESI- MS in the UHT milks. Protein lactosylation increased during the storage period of 6 months at 20 °C. Both the initial extent and the rate of lactosylation positively correlated with the number of lysine residues in the different proteins. An exponential or linear correlation with furosine concentration could be established for major and minor lactosylated proteins, respectively. [ABSTRACT FROM AUTHOR]

In this study, the degree of inhomogeneity in crystallized fat samples was evaluated in terms of texture, solid fat content, microstructure, and triacylglycerol (TAG) composition. Four different cocoa butter alternatives based on symmetric or asymmetric monounsaturated TAGs and with different contents of palmitic acid (a POP-rich fat and a PPO-rich fat) and steric acid (a SOS-rich fat and a PSO-rich fat) were studied. Significant differences ( P < 0.001) in hardness between top and bottom was observed for all fats except the PSO-rich fat. The inhomogeneous consistency was shown to be a consequence of microstructural variation within the crystallized fats. No differences in solid to liquid ratio, melting points, or polymorphic behavior between top and bottom of fats were found. Sedimentation during the crystallization process could explain the observed inhomogeneity. Although sedimentation most likely is limited to the early stages of the crystallization process due to network formation, sedimented crystals influence the crystallization kinetics and thus introduce microstructural variations. This hypothesis is supported by findings of a higher amount of trisaturated TAGs in the bottom compared with the top of crystallized fats. The PSO-rich fat crystallizes fast compared with the other evaluated fats, which explains the more homogeneous texture of the PSO-rich fat compared with the other evaluated fats. Practical applications: Fat crystallization plays an important role for the texture of many food products such as chocolates, confectioneries, margarine, and butter. Correct analysis of texture is thus critical when evaluating fats for the food industry. This study emphasizes that inhomogeneity in the consistency could be of practical importance for evaluation of the mechanical and textural properties of crystallized fats for instance by compression tests or small deformation rheological testing of fat samples prepared in molds or with needle penetration tests, which only include the top of a fat sample. This study shows an inhomogeneous consistency of crystallized fat samples due to microstructural variation within the fat. [ABSTRACT FROM AUTHOR]

Visible aggregates formed during storage in acidic whey protein isolate (WPI) dispersions represent a challenge to the beverage industry. Batch-to-batch variations are observed that prevents consistent quality and shelf-life prediction. Heat-treatment of WPI dispersions at 120 °C for 20 s instead of conventional heating at 95 °C for 180 s often prevents the aggregate formation, and varying levels of divalent cations were proposed to contribute to the observed batch-to-batch variations. In this study, the composition of the visible aggregates was examined. Caseinomacropeptide (CMP) was enriched in the visible aggregates compared with the surrounding clear liquid. Disruption of electrostatic interactions between glycosylated and non-glycosylated CMPs were studied by addition of calcium, acidification, and enzymatic de-sialidation. The treatment strategies each significantly decreased time-dependent turbidity development in acidic WPI dispersions. This suggests that the storage-induced aggregates may be prevented by disruption of electrostatic interactions between negatively-charged sialic acid residues and positively-charged amino acids. [ABSTRACT FROM AUTHOR]

Due to the growing interest in creating mixed plant-dairy protein emulsion-based foods, it is important to understand how to include plant-dairy protein mixes in existing and new formulations. The aim of this work was to study the dynamics occurring at the oil-water interface in systems containing mixtures of pea and whey protein isolates. By using drop tensiometry combined with bulk-phase exchange, we compared the interfacial dynamics and viscoelastic properties of plant-dairy protein interfaces formed through simultaneous or sequential adsorption. Differences in the adsorption isotherm and interfacial behaviors suggest different interfacial structures for simultaneous and sequential addition. These results were supported by changes in the interfacial composition observed in bulk emulsions. Bulk emulsions prepared with simultaneous adsorption of whey and pea protein isolate showed the lowest creaming stability. The results show how different emulsion properties can be achieved using the same protein mixtures by fine tuning their interfacial composition to reach maximum product functionality. [Display omitted] • Both pea and whey readily adsorb at oil-water interfaces in mixed systems. • The colloidal state of pea proteins strongly impacts their interfacial behavior. • Pea and whey protein isolates form viscoelastic interfaces. • Altering the order of protein addition affects the final interfacial properties. • Simultaneous addition of pea and whey proteins may cause emulsion instability. [ABSTRACT FROM AUTHOR]

The effect of enzymatic activity in direct steam infusion heat treated milk with ultra-short holding times (>150 °C for <0.2 s) on age gelation during storage was investigated. Preheating at either 72 or 95 °C for 180 s was performed. Milk pre-heated at 72 °C showed extensive proteolysis and exhibited bitter off flavour and contained <40% intact αS- and β-caseins after 6 weeks storage at 20 °C. No proteolysis of κ-casein was detected. Plasmin was identified as active protease and activation of plasminogen was observed as an increase in the rate of casein hydrolysis. Proteolysis in the stored samples correlated with a decrease in pH and with changes in colour. Gelation occurred after 10 weeks along with an increase in viscosity and extensive proteolysis of αS- and β-caseins. In conclusion, plasmin activity was involved in age gelation and bitterness caused by proteolysis was the shelf-life limiting factor. [ABSTRACT FROM AUTHOR]

Abstract: A spectrophotometric assay for plasmin and plasminogen-derived activity in dairy products was optimised and extended to determine plasmin and plasminogen-derived activity in turbid samples of dairy products. The method was validated by assessing reproducibility, repeatability, level of detection and recovery of plasmin activity in different sample matrices. Plasmin activity in raw milk was not affected by skimming, but decreased by 30% in pasteurised and homogenised whole milk, leading to an underestimation of plasmin activity. The effects of dissociation of plasmin and caseins by ε-aminocaproic acid (EACA) plus NaCl on the plasmin activity were investigated. Comparison of pasteurised milk with a micellar casein solution showed that the dissociation of plasmin and caseins on adding EACA and NaCl decreases interference by caseins, but increases inhibition of plasmin with serum-based inhibitory components. The level of detection and repeatability of this method for plasmin activity analysis were improved compared with previous spectrophotometric assays. [Copyright &y& Elsevier]

Abstract: Whey protein concentrate (WPC) was heat treated by use of the novel heat treatment method of Lenient Steam Injection (LSI) to elucidate new functional properties in relation to heat-induced gelation of heat treated WPC. Denaturation was measured by both DSC and FPLC, and the results of the two methods were highly correlated. Temperatures of up to 90°C were applicable using LSI, whereas only 68°C could be reached by plate heat exchange before coagulation/fouling. Denaturation of whey proteins increased with increasing heat treatment temperature up to a degree of 30–35% denaturation at 90°C LSI treatment. A subsequent spray drying was found not to affect the degree of denaturation. WPC gels were found to become softer, as function of increasing temperature during LSI treatment of WPC. Furthermore, pH and conductivity of WPC largely affected both the axial stress and the Hencky strain of WPC gels. Industrial relevance: Due to the wide application of whey proteins as functional ingredients in foods, the investigation of new functionalities of WPC is highly significant. Very little has been published on direct heat treatment of WPC, and the impact hereof on the functionalities of WPC is novel to the food industry. [Copyright &y& Elsevier]

Protein fractionated from alfalfa exhibits promising properties for exploitation as food ingredient. However, further knowledge and improvement of the functional properties is essential to increase the potential for commercial use. This might be obtained by acid or alkaline pH shift processes. The effect of pH shifting compared to controls (buffer solutions) at different pH-values were investigated concerning protein solubility, foamability, and gelation. The effect of salt (NaCl) concentration was also studied. At pH 12, more cross-linkages were observed as lysinoalanine, lanthionine and also conversion of L-Ser to D-Ser was highest at pH 12. Therefore, the pH-shift method with pH 11 was chosen for further investigation, which increased the solubility from 50% to 70–80%. The alkaline pH shift (pH 11) increased the foam overrun and stability, where pH 7 reached the highest stability with >60% foam volume remaining after 1 h. The protein gel strength showed remarkable potential with the alkaline pH shift method with re-adjusting to pH 7, reaching 2584 Pa with 72 g/L protein. For the acid pH shift with re-adjustment to pH 2 followed by pH 3, the foam overrun increased to 140% and protein solubility to 57% at low protein concentration (2 g/L). Addition of salt (185 mM NaCl) increased the foam overrun at pH 5 and 7 for all samples. Overall, these results indicated that prior alkaline pH treatments and salt can increase the potential of alfalfa protein in terms of certain functionality in foods. [Display omitted] • A pH of 11 for alkaline pH shift was chosen as it maintains the protein quality. • Alkaline pH shift increases solubility, foamability and gelation of alfalfa protein. • Acid pH shift increases foam overrun and solubility at low protein concentration. • Addition of salt increases alfalfa protein foam overrun at pH 5 and 7. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate whether emerging multimodal microscopy techniques combined with quantitative image analysis were capable of detecting differences in the microstructure of model dairy systems, and to evaluate whether hydrodynamic cavitation led to differences in microstructure compared to pressure homogenisation. Hydrodynamic cavitation and pressure homogenisation were combined with severe heat treatment to obtain milk samples of different degrees of fat homogenisation and different degrees of whey protein denaturation. Glucono-δ-lactone (GDL) induced acid milk gels and stirred yoghurts were produced from the treated milks, followed by rheological analysis and evaluation of the microstructure by multimodal coherent anti-stokes raman scattering and two-photon excitation microscopy combined with auto and cross-correlation image analysis. Autocorrelation analysis of the protein network of GDL-gels could quantitatively describe differences in acid gel strength, and results indicated that differences in the degree of homogeneity and branching of the protein network were linked to differences in size and shape of the protein domains formed during acidification. However, for the stirred yoghurts, the autocorrelation analysis was limited by the heterogeneous structure of the protein network. By cross-correlation analysis, quantification of the relative distribution of fat and protein was possible for both GDL-gels and yoghurts. Results indicated that severe heat treatment of the milk base translated into differences in the interaction between fat globules and the protein network, which could be explained by a relatively higher degree of whey protein association with the milk fat globule membrane. Image 1 • Effects of heat treatment, cavitation and homogenisation of milk are studied. • Resulting GDL-gels and yoghurts exhibited different rheological properties. • Image analyses differentiated the protein network on micrographs of GDL-gels. • Differences in the protein distribution around fat globules were quantified. • A heterogeneous structure of yoghurts limited the image analysis. [ABSTRACT FROM AUTHOR]