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Iridescence extent is commonly evaluated by sensory analysis but it is a time-consuming and cost-intensive method. A low-cost, rapid and objective alternative is digital image analysis. Here we report the development of an image analysis method for quantification of iridescence in meat products. Two segmentation techniques (global thresholding and k-means clustering algorithm) were tested for their capability to divide images into segments of iridescent and non-iridescent areas. Images segmented using k-means clustering algorithm resulted in slightly higher iridescent areas than images segmented with global thresholding (mean difference of 1.24%) but no significant difference (P > .05) between the iridescent areas calculated by both methods was observed. Almost perfect agreement (κ = 0.800, p = .001) was observed between the image analysis and the visual evaluation. The results from this study showed that digital image analysis is an effective tool for evaluating surface iridescence in meat and meat products.

The application of co-extruded calcium alginate casings is becoming more and more popular for the production of dry fermented sausages with small caliber. However, the formation of white efflorescence in coextruded sausages is a substantial problem for manufacturers. Previous studies had shown though that addition of chelators can inhibit formation of efflorescences in non-coextruded sausages. Effect of addition of such compounds to alginate gels used for formation of casings in the co-extrusion technology is yet unknown. Therefore, the influence of calcium chloride (crosslinking solution) and various chelators on the properties of the alginate gels and casings were investigated. The study showed that the influence of increasing concentrations of CaCl2 in the crosslinking solution is of minor importance for the stability of the casings. However, depending on the chelator the stability was either increased, decreased or the same as the control. The addition of citrate did not change the properties, the addition of the polyphosphate P69 significantly increased (p

Yücetepe, Aysun ( Aksaray, Yazar ), Liposomal systems are promising carrier systems for the delivery of phenolic compounds. However, the commercial usage of aqueous liposomal dispersions is still challenging. In this study, an aqueous liposomal dispersion which was loaded with sour cherry phenolics (SCE) were converted into powder form by spray drying to make the use of such delivery systems industrially applicable. Then, the obtained SCE loaded liposomal powder was incorporated into a stirred-type yoghurt system. During 21-day storage at 4 °C, sensorial and physicochemical properties such as pH, color, and whey syneresis of yoghurt with SCE loaded liposomal powder were investigated. According to the results, SCE was successfully encapsulated in aqueous liposomal dispersion and spray dried. Spray drying process did not degrade phenolic compounds that were encapsulated by liposomes. The structure of liposomes in the sample contained spray dried liposome encapsulates with SCE (Y-encapsulated SCE) was the most stable in yoghurt during storage which also affects the stability of SCE. Thus, SCE showed the lowest degradation level in this sample among all samples in terms of total phenolics and antioxidant capacity. This means that the SCE in yoghurt with liposomal encapsulates was protected during the storage period. The spray drying process also led to an increased total dry solid and reduced syneresis. Although syneresis of yoghurt containing liposomal powder with SCE and without SCE was the lowest, control yoghurt was chosen to be the best according to the sensorial evaluation.

The aim of the following study was to compare three different foaming methods and investigate the influence of the applied energy density (Evol) on the following foam properties: foam capacity (FC), sauter-diameter (d3,2) and interfacial area (IA). Foams were prepared with sodium caseinate, porcine gelatin, and egg albumen (c = 1–10 wt%) by whipping, spraying, and sparging employing up to 5 different Evol (3.3 × 104 J m−3–4.0 × 108 J m−3). First, whipping resulted in a FC that depended on the protein concentration and the type of protein with gelatin having the highest FC (837.2% ± 89.5%) at 1 wt% among used the proteins. There was no linear trend between FC and concentration of gelatin whipped foams. In contrary, egg albumen whipped foams revealed a linear relationship between FC and concentration, with the highest foam capacity at c = 10 wt% (675.7% ± 83.0%). An increase in Evol led to an increase in FC and in IA, but in a decrease in d3,2 for all whipped foams. Second, spraying showed for all proteins an increase in FC with increasing concentration up to a plateau at >5 wt% (caseinate), >2 wt% (gelatin), >2 wt% (egg albumen). No clear correlation between foam properties and Evol was observed for spraying. Third, sparging yielded a FC that was less affected by concentrations used in this study. Increasing the Evol during sparging led to a higher FC and IA, while the d3,2 slightly increased. Overall, no correlation between the methods, proteins, and energy density was obtained because the protein structure and foaming method influenced the foamability. However, Evol in combination with IA as output parameter was shown to be most suitable to compare the foamability of the proteins and the methods.

This study describes the interfacial and emulsifying properties of a plant-based saponin glycyrrhizin and its aglycone 18β-glycyrrhetinic acid derived from licorice root (Glycyrrhiza glabra L.) to enable first insights into a potential structure-function relationship. First, the surface activity of glycyrrhizin and its aglycone at air-water and oil-water interfaces, and the viscoelastic behavior at an oil-water interface was examined. Second, the emulsifying properties by preparing oil-in-water emulsions (100 g oil/kg emulsion, pH 7) by high-pressure homogenization was evaluated. Both glycyrrhizin and its aglycone reduced surface and interfacial activity only

Microencapsulation of fish oil by spray drying is an established method to protect polyunsaturated fatty acids against oxidation by separating the environmental O2 from encapsulated lipids. Some oil droplets are not fully embedded within the matrix and are exposed to the environmental O2. The aim of the study is to determine the oxidation rate of the non-encapsulated- and encapsulated oil as well as the contribution of each lipid fraction to the overall oxidation of the encapsulates. The amount of non-encapsulated oil was varied by changing the preparation of the O/W emulsions (18% fish oil; 27% solids) regarding protein to oil ratio (0.02–0.22 (w/w)) and applied homogenization pressure (0.5/0.1–25/5 MPa). Emulsions were spray dried using a pilot plant drier with a maximal water evaporation rate of 30 kg h−1 operated at an inlet and outlet temperature of 160 °C and 85 °C, respectively. The obtained particles were analyzed in terms of water content, aw, particle size, non-encapsulated oil concentration and encapsulation efficiency. The amount of hydroperoxides in the total-, encapsulated- and non-encapsulated oil was determined over a storage period of 6 weeks. The non-encapsulated oil concentration was in the range of 2.20 and 18.45% which corresponds to an encapsulation efficiency between 53.82 and 93.56%. The sum of hydroperoxides in the non-encapsulated- and encapsulated oil equaled the amount detected in the total oil. The non-encapsulated oil oxidized on average 7.4 ± 2.0 times faster than the encapsulated lipids, whereas its contribution to the overall oxidation was minor, due to its low amount. The encapsulated oil was the main contributor to the overall oxidation and oxidized, even though it was fully embedded within the matrix.

Glycation of proteins via the first stage of the Maillard reaction is capable of improving their stability but not economically feasible yet. This work reports the glycation of whey protein isolate (WPI) with maltodextrin at a high yield after heating electrospun fibers made from the reactants. Glycoconjugates were characterized by Fourier transform infrared spectroscopy (FTIR) and SDS-PAGE. The binding ratio between WPI and maltodextrin was assessed via the free amino groups. The molecular weight of the conjugates and the reaction yield were studied by size exclusion chromatography. The impact of different mass ratios between WPI and maltodextrin in the fibers (5:95, 10:90, 20:80, and 25:75 w/w) was investigated. With increasing WPI content, the binding ratio of maltodextrin decreased from ∼2.1 to ∼1.2. Preferably small polysaccharides (2-13 kDa) from the maltodextrin reacted. Protein specific reaction yields of up to 44.52 ± 7.46% w/w were demonstrated in all WPI-maltodextrin fibers after heating.

The meat industry often applies hydrocolloids (not label-free) to improve quality attributes of meat products including reconstructed cooked ham. A new approach to improve product quality could be the usage of in-situ Exopolysaccharide (EPS)- forming lactic acid bacteria (LAB) provided that these strains are able to produce EPS in meat matrices under typical processing conditions (here: cooked ham). Two homopolysaccharide- (L. curvatus TMW 1.624 and L. sakei TMW 1.411; 106 CFU mL ) and heteropolysaccharide-forming LABs (L. plantarum TMW 1.1478 and TMW 1.25; 106 CFU mL ) were hence examined for EPS formation in a cooked ham model system consisting of minced pork topside (

Protein solubility in water is a key property of food proteins. The aim of this work was to study the solubility and microstructural properties as a function of pH of both protein fractions (water-soluble (WSPE) and water-insoluble protein extracts (WISPE)) obtained from the microalga Chlorella protothecoides, which is promising for food use. Protein solubility was determined as the ratio of protein concentration in the supernatant after centrifugation to total protein concentration. An unusually high solubility and only slight gravitational separation across a very broad pH-range (2−12) were observed for the WSPE with a minimum protein solubility of 84.3 ± 2.2% at pH 2. The origin of this high pH-independent protein solubility was attributed to a high degree of glycosylation and a high amount of hydrophilic amino acids. In contrast, the WISPE was found to contain strongly aggregated proteins, and these large aggregates separated rapidly from solution by gravitation independent of the pH. This corresponded to their protein solubility, which was overall low in the pH-range of 2–11, and only increased at pH 12 to a maximum solubility of 26.9 ± 2.8%. These results suggest that the WSPE of Chlorella protothecoides may exhibit unique properties for food formulations, allowing for example for both acidified, neutral or slightly alkaline foods to be formulated, whereas WISPE may be more suited for foods where phase separation is rather slow.

The incorporation of novel plant-based proteins into foods is often challenging due to an unacceptable bitter sensation. Typically, a combination of electrostatic and hydrophobic forces contributes to the proteins' bitterness. The current study therefore focuses on the development of electrical properties on cationic plant proteins to reduce their overall bitterness in order to improve the perceived sensorial acceptance. As such, we utilized a simple mixing process to induce complex coacervation of oppositely charged biopolymers under acidic conditions. Pea and potato protein stock solutions were mixed with apple pectin (DE 71%) solutions at various biopolymer ratios to modulate the electrical, rheological, and sensorial properties of the complexes. Whey protein hydrolyzate was used as a control sample. Surface charge measurements revealed a transition from positive to negative values as the pectin concentration was increased regardless of the plant protein, whereas stable dispersions without sedimentation were observed above a critical pectin : protein ratio of 1. Low and intermediate biopolymer ratios (1) promoted aggregation and led to rapid sedimentation. Sensory evaluation showed that bitterness scores depended on protein type and decreased from pea proteinpotato proteinwhey protein. Moreover, bitter off-notes were increasingly reduced with increasing pectin : protein ratios; however, high dispersion viscosities above 0.05 Pa s led to undesirable texture and mouthfeel of the biopolymer dispersions. Our results might have important implications for the utilization of novel plant proteins in food and beverage applications.

The formation and subsequent enzymatic and chemical cross-linking of heteroaggregates from oppositely charged oil-in-water (O/W) emulsions was investigated. For this purpose, 10% (w/w) oil-in-water emulsions (d43

Production of pasta-filata cheese comprises a particular scalding and stretching step to obtain the unique fibrous structure. A simulation of this process on small scale was conducted with cheese curd cubes of 10 × 10 × 10 mm. Stretching was initiated with a texture analyzer and a custom-built geometry in a water bath at 60C. Three parameters were varied: compression rate, pretempering time before compression and duration of compression. The force decline during compression was linearized to receive time independent parameters k1 (y-axis intercept), k2 (slope) and stress relaxation (SR). Further, relaxation time (RT) and Deborah number (De) were calculated. The RT decreased from 2 to 0.6 s with a temperature increase from 40 to 60C. The SR after 20 s of compression increased from 10 to 23% with increasing temperature due to network formation as shown by confocal laser scanning microscopy. Anisotropy increased with decreasing De. Practical Applications When producing pasta-filata cheese, time and temperature behavior of cheese curd has to be considered during plasticization to obtain the typical fibrous structure. Conclusions for the industry are: (1) plasticization needs time (preheating) as heat transfer in the curd is slow; (2) relaxation of the soft material limits anisotropic structuring; (3) with increasing temperatures relaxation time (RT) decreases, and the process time for stretching can be shortened; and (4) structural changes in the microgel particles during heating induce a continuous protein network with elastic properties which is typical for pasta-filata cheese production. These results indicate that pasta-filata cheese with less strings when manually teared, or less anisotropy when visualized by confocal laser scanning microscopy can be modified by adapting the process parameters. Fibrous, anisotropic structure (stringiness) is claimed to be enhanced with increasing residence times and/or higher process temperatures during the stretching process.

The miscibility behavior of mixed surfactant systems and the influence of extrinsic parameters are crucial for their application as emulsifiers. Therefore, the objective of this study was to evaluate the miscibility behavior of mixed systems composed of commercial Quillaja saponin and a co-surfactant, namely sodium caseinate, pea protein, rapeseed lecithin, or egg lecithin. These mixtures were evaluated macro- and microscopically at different concentration ratios (maximum concentration 5% w/v) at pH 3, 5, and 7 at 25 °C. The individual ingredients were also assessed for their charge properties and surface hydrophobicity. The results showed that Quillaja saponin-caseinate mixtures were miscible only at pH 7, and showed aggregation and precipitation at lower pH due to increasing electrostatic attraction forces. Rheological measurements showed that Quillaja saponin-pea protein mixtures formed gelled structures at all tested pH values mainly via association of hydrophobic patches. Quillaja saponins mixed with rapeseed lecithin were miscible at all tested pH values due to electrostatic repulsion. Quillaja saponin-egg lecithin mixtures aggregated independent of pH and concentration ratio. The microscopic analysis revealed that the lower the pH and the higher the Quillaja saponin ratio, the denser were the formed Quillaja saponin-egg lecithin aggregates. The results are summarized in ternary phase diagrams that provide a useful tool in selecting a surfactant system for food applications.

The impact of precursors such as creatine, creatinine, and glucose on the formation of mutagenic/carcinogenic heterocyclic amines (HAs) were studied in patties of 9 different animal species equally heat treated with a double-plate contact grill. All grilled patties of the various species (veal, beef, pork, lamb, horse, venison, turkey, chicken, ostrich) contained several HAs such as MeIQx (2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline; 0.5-1.4 ng/g), 4,8-DiMeIQx (2-amino-3,4,8-trimethylimidazo[4,5-f] quinoxaline, 0 to 1.3 ng/g), PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine, 1.2 to 10.5 ng/g), harman (1-methyl-9H-pyrido[3,4-b] indole; 0.5 to 3.2 ng/g), and/or norharman (9H-pyrido[3,4-b]indole 0.5 to 1.9 ng/g). Residual glycogen (glucose) content varied greatly from 0.07 to 1.46 wt% on a dry matter (DM) basis. Total creatin(in)e content in raw meat (1.36 to 2.0 wt% DM) hardly differed between species, except in turkey and ostrich (1.1 wt% DM). Chicken contained, compared to all other species, very low concentrations of glucose (0.07 wt% DM) and the highest levels of nonprotein nitrogen compounds. The free amino acids lysine (r = 0.77, P < 0.001), tyrosine, phenylalanine, proline, isoleucine, and aspartic acid (r = 0.47-0.56, P < 0.05) showed significant correlation to PhIP in chicken. Also a linear correlation was found to exist between PhIP (r = 0.87, P < 0.001) and MeIQx (r = 0.35, P < 0.01), and the molar ratio of creatin(in)e to glucose, respectively. Harman as co-mutagens was linearly correlated to the concentration of glucose (r = 0.65, P < 0.001). By contrast, norharman was not significant correlated to glucose levels.

Shear-induced morphological changes of phase-separated whey protein isolate (WPI; 5%, w/v) droplets dispersed in high methoxyl pectin solutions (2%, w/v) subjected to pH changes (6.1 → 5.2 → 3.2) and addition of salt (200 mM NaCl) were investigated. Systems were sheared (0.1–50 s−1) on an optical rheometer and sizes and morphologies determined by microscopy and light scattering techniques. Apparent viscosities were calculated from shear stress versus strain rate measurements. The microstructures of phase separated WPI – pectin dispersions at pH 6.1 was altered at low to intermediate shear rates (0.1–10 s−1) from initially containing spherical particles to elongated ones. Shearing also led to increases in particle size due to shear-induced coalescence. At high shear rates (>10 s−1) particle size decreased due to droplets being disrupted. Morphologies of dispersions changed substantially when pH was decreased to 5.2 yielding core–shell like WPI droplets surrounded by aggregated pectin – whey protein isolate “shells”. Those structures were substantially less sensitive to shear-induced disruption, and high deformational forces were required to break them up. At pH 3.2 small pectin – WPI aggregates were formed that were resistant to superimposed shear stresses. Addition of salt increased shear-induced droplet coalescence at pH 6.1 but had little influence on morphology of structures at pH 5.2 and 3.2. Results were explained in terms of modulations of molecular interactions between the two biopolymers yielding either phase-separated WPI droplets suspended in pectin with ultralow interfacial tensions or electrostatically-networked biopolymer aggregates with high interfacial tensions.

Nanoemulsions can be formed spontaneously from surfactant-oil-water systems using low energy methods. In this work, we showed that the droplets in oil-in-water nanoemulsions fabricated by spontaneous emulsification could be coated with an anionic biopolymer (beet pectin) using electrostatic deposition. Nanoemulsions were formed by titrating oil (medium chain triglycerides) and surfactant (polyoxyethylene sorbitan monostearate+lauric arginate) mixtures into an aqueous solution (10 mM citrate buffer, pH 4). Lauric arginate was used to generate a positive charge on the droplet surfaces, thereby enabling subsequent electrostatic deposition of anionic pectin. Extensive droplet aggregation occurred when intermediate pectin concentrations were used due to bridging flocculation. However, stable anionic pectin-coated lipid droplets could be formed at high pectin concentrations. These results demonstrate the possibility of tailoring the functionality of lipid nanodroplets produced by spontaneous emulsification.

Micelles are increasingly used as carrier systems. In previous studies, we have shown that the blockcopolymers PEO13-PPO30-PEO13 and αs-casein form micelles at distinct temperature and concentration ranges. The aim of the study at hand was to determine the thermodynamics of this micelle formation by isothermal titration calorimetry (ITC). For αs-casein, micelle formation was investigated as a function of temperature from 15 – 30 °C at pH = 6.6, while micelle formation of PE6400 and of mixtures of PE6400 with αs-casein was studied from 29 – 31 °C. In addition, the influence of increasing αs-casein mole fraction from 0.135 × 10−3 to 3.6 × 10−3 was examined at 30 °C. In case of αs-casein, the standard experimental approach could be used while we developed a new experimental approach for PE6400 and for the mixture. The results show that the enthalpy of demicellization increases for αs-casein and decreases for PE6400 with increasing temperature. In case of the mixtures, the enthalpy of demicellization was not influenced by either the temperature or the αs-casein mole fraction. The results obtained for αs-casein suggest that the micellization follows a “shell-model”. In the case of the mixtures, αs-casein is likely to form the core of the micelle while the outer part appears to be composed of PE6400. The mixing properties were antagonistic, which was shown by comparing the enthalpies of PE6400 with those of the mixtures. The results show that ITC is a powerful tool to precisely determine micellization properties not only of the single but also of mixed surfactant systems.

Uniform suspension of particulates (salt or spices) in oil-based marinades requires a gel behavior of the matrix. This can be achieved by adding a solid fat to the liquid oil. Besides rheology, appearance and thermal stability are important for the utilization as marinades. The influence of solid fat concentration (c fat = 2.5–5.5 wt%) and average cooling speed (1.4, 2.6, and 4.7 °C/min) on the functional properties of oil-fat gels from palm fat and canola oil was investigated. Oil-fat mixtures showed complex physiochemical behavior depending on the solid fat concentration and cooling rate. All samples had a shear-thinning behavior. Yield stresses and apparent viscosities increased at a constant cooling rate with increasing solid fat concentration. Frequency dependence of storage and loss modulus showed a transition from a viscous solution to a weak gel at c fat > 3.5 wt%. Samples at increasing cooling rates transitioned to weak gels at lower fat concentration (2.5 wt%). Mixtures became turbid and increasingly whiter as both solid fat concentration and cooling rates increased, which was explained by increased light-scattering by fat crystal aggregates. Results show the critical importance of proper formulation and preparation conditions on the functionality of oil-based marinades.

Collagen can be modified by addition of chaotropic or kosmotropic salts of the reversed Hofmeister series. Hence, telopeptide-poor collagen type I was suspended in H2SO4 (pH 2) and 0.05-0.5 M KCl and KNO3 (chaotropes), as well as KI and KSCN (kosmotropes). Rheological parameters, including storage and loss modulus, intrinsic viscosity, and critical overlap concentration, were assessed and the microstructure was characterized by applying confocal laser scanning microscopy and scanning electron microscopy. The addition of up to 0.1 M KCl and 0.05 M KNO3 increased the intrinsic viscosity from 1.22 to 1.51 L/g without salt to a maximal value of 1.74 L/g and decreased the critical overlap concentration from 0.66 to 0.82 g/L to a minimal value of 0.57 g/L. Higher salt concentrations increased the collagen-collagen interactions due to ions withdrawing the water from the collagen molecules. Hence, 0.1 M KSCN delivered the largest structures with the highest structure factor, area value and the highest critical overlap concentration with 17.6 L/g. Overall, 0.5 M salt led to salting out, with chaotropes forming fine precipitates and kosmotropes leading to elastic three-dimensional networks. The study demonstrated that collagen entanglement and microstructure depend strongly on the ionic strength and type of salt.

Antimicrobials are components added to foods to inhibit microbial growth or inactivate microorganisms. The use of increasingly diverse raw materials coming from a great variety of sources and regions, consumer requirements to process foods minimally to preserve as much of the original character of the raw materials as possible, and the distribution of foods over greater and greater distances, has led to a re-discovery of this traditional approach to food preservation. Nowadays, modern food antimicrobial research focuses on the development of new synthetically derived antimicrobials, or on the discovery of antimicrobially active compounds from natural sources. This has led to the introduction of many new compounds that could be used by food scientists to enhance the quality and safety of food. Unfortunately, many of these antimicrobials demonstrate excellent activities against food pathogens and spoilage organisms in model media but fail to be effective when used in complex foods. This paradox of a high activity in microbial model systems and a low activity in foods as well as the seemingly random extent of such activity losses are still not well understood. This article presents results of some relevant studies that illustrate this phenomena. From those studies, some mechanistic conclusions are derived that may be used to explain this phenomena. These could be used to better forecast activity losses of a particular antimicrobial in a given food system. Finally some conclusions highlighting future research needs are presented.

Filled hydrogel particles fabricated from natural lipids and biopolymers can be utilized as tailor-made encapsulation and delivery systems. In the present study, the impact of nanoemulsion fabrication method (low energy versus high energy) on the retention and release of a lipophilic bioactive component (curcumin) and of lipid droplets from calcium alginate beads was investigated. Initially, curcumin was dissolved within an oil phase, and then the oil phase was encapsulated within the hydrogel beads using a two-step process. First, nanoemulsions composed of the same constituents (medium chain triglycerides, Tween 60, curcumin, and phosphate buffer) were prepared using either low energy (spontaneous emulsification) or high energy (microfluidization) homogenization. Second, the nanoemulsions were mixed with alginate solutions (0.25–1.5%), and then the resulting mixture was dripped into calcium solutions (10–500 mM) to form filled hydrogel beads. Unloaded beads became more spherical and rigid with increasing alginate and calcium concentrations. Turbidity and spectrophotometry measurements showed that the amount and extent of curcumin and lipid droplet release from the hydrogel beads decreased with increasing alginate and calcium concentration, which was attributed to a reduction in the pore size of the hydrogel matrix. In particular, a high amounts of curcumin released were observed in delivery systems containing high Tween 60 concentrations, which was attributed to rapid diffusion of curcumin-loaded surfactant micelles out of the beads. These results have important implications for the design of delivery systems to entrap and control the release of lipophilic bioactive components within filled hydrogel particles.

The focus of this study was the taxonomic identification of a collection of 40 Staphylococcus carnosus strains to the species, subspecies and strain level. These strains were screened for physiological activities suitable for their use as starter cultures, in particular as starter cultures for the processing of raw ham. Consequently, the strains were tested for their ability to grow in Brain Heart Infusion broth at different NaCl and NaNO2 concentrations. We found that most of the S. carnosus strains tested were able to grow at NaCl concentrations of up to 150 g l−1 and at NaNO2 concentrations of up to 400 mg l−1. Essential metabolic activities, such as nitrate reduction, proteolysis and lipolysis, were analysed in vitro. Three S. carnosus subsp. carnosus strains produced > 0.6 mol NO2 per 1.0 × 107 colony forming units. Twenty-six S. carnosus strains showed proteolytic activity on calcium caseinate agar, and one S. carnosus subsp. utilis strain showed activity on agar supplemented with sarcoplasmic proteins. Lipolytic activity was found in 34 strains. Of these 40 S. carnosus strains four were found to fulfil the multiple metabolic requirements necessary for their use in industrial meat fermentation processes.

Collagen gels were modified by addition of co-gelling proteins to obtain gels with new functionalities. Microstructure and rheology of these mixed telopeptide-poor collagen gels were assessed. It was assumed that proteins with a low molecular weight strengthen the collagen structure by embedding themselves in the matrix, while high molecular weight proteins weaken the structure by interfering with the assembly of the network. Different combinations of collagen (2.8–5.19% (w/w)) and co-gelling protein concentrations (0.36–2.14% (w/w)) were applied. Blood plasma protein, soy protein isolate, whey protein isolate, and gluten were used as co-gelling proteins. The storage modulus was measured as an indicator of the gel strength. Frequency sweeps (0.1–10 Hz) at 1% strain were conducted in the linear viscoelastic region. The position of the co-gelling proteins in the collagen matrix was examined via both confocal laser scanning and scanning electron microscopy. The results showed weakening effects for whey protein isolate. The addition of blood plasma protein did not affect the rheology, but the microstructure was influenced, featuring more fibrillar structures in the pores compared to the reference gels. Gluten seemed to lead to phase separation, forming a separate layer without interacting with the collagen matrix. The greatest impact was found for soy protein isolate, with a strengthening effect indicated by increased storage moduli and well distributed and embedded soy protein isolate in the collagen network. In conclusion, co-gelling proteins display a suitable approach to modify collagen strength in order to create matrices with new functionalities, such as co-extruded sausage casings with modified knack or snap.

For concentrated model suspensions consisting of hard spheres, besides the volume fraction, the particle size distribution affects rheological properties, where the relations have been investigated and mathematically described in detail. In contrast, food products often represent complex multiphase systems what demands the consideration of other parameters, e.g., particle interaction and deformation. The principles have been shown to be appropriable to chocolate, which consists of non-spherical, hard particles suspended in a Newtonian fluid (cocoa butter). However, work for concentrated fermented milk products, e.g., fresh cheese, consisting of soft microgel particles with high serum binding is lacking. Therefore, the aim was to produce and characterize different particle size distributions by modifying the post-processing during fresh cheese production (protein content 8.0%). Tempering of the standard generated mainly fine, medium, and coarse particle fractions, and, likewise, increased rheological properties (storage modulus, shear viscosity) and synaeresis. Subsequent blending adjusted intermediate levels. Additionally, with increasing size ratio of the particle fractions generated by tempering, the rheological properties of the blended microgel suspensions were affected differently, e.g., high particle size but low shear viscosity. Besides the size ratio, that was related to the particle properties and fundamentals of multimodal particle mixtures.

The effect of pH change, salt addition or sequences of pH change followed by salt addition or vice versa on the structure of a whey protein isolate – pectin dispersion obtained from a phase separated system after mild homogenization was studied. Solutions of whey protein isolate and pectin were combined at pH 6.1, allowed to phase separate and then mildly homogenized to form a dispersion consisting of whey protein isolate droplets in a surrounding pectin phase. The dispersion was then subjected to a pH change (6.1 → 5.2 → 3.2), to an addition of NaCl (0–200 mM) or to a combination thereof. The systems morphology, size, appearance, and rheology were then characterized by optical and confocal microscopy, static light scattering, turbidity measurements, visual inspections and steady shear rheometry to gain insights into structural rearrangements. Results indicated profound alterations in the structure of dispersion both when pH was changed and when NaCl was added. Formation of core–shell structures from the whey protein isolate droplets were observed when pH was decreased while clusters of droplets were formed when NaCl was added. The type of sequence (pH then salt or salt then pH) had no influence on the morphology of the structures created. Results were discussed in the context of changes in molecular interactions between the two biopolymers involved in transitions from segregative to aggregative phase separation processes. The gained insights may be of importance to food manufacturers intended on creating new structures from mixtures of proteins and carbohydrates.

Continuous operating vane pump-grinder systems are increasingly replacing bowl choppers in the industrial manufacturing of sausages. However, their use has traditionally been limited to coarsely ground, dry-cured sausages rather than finely emulsified sausages. We hypothesize that simultaneous alteration of volume flow rate $$ \overset{\cdot }{V} $$ and knife rotational speed n grinder may allow for the degree of dispersion to be freely modified, thereby facilitating production of emulsified meat batters. Coarsely ground raw material mixtures were processed at volume flow rates $$ \overset{\cdot }{V} $$ of 3 to 60 L/min and knife rotational speeds n grinder of 11.8 to 236.0 rpm in a vane pump-grinder system. The structure of the sausages was analyzed using image analysis. Texture, water-binding, color, and content of solubilized proteins of the meat batters were determined. A linear relationship between the sausage structure and the volumetric energy input E V was found. The color values a* and b* (a* ∼9.9, b* ∼7.0) did not differ noticeably between samples processed at different volume flow rates and knife rotational speeds. However, the lightness L* correlated with the sausage structure. Released serum content increased with decreasing volumetric energy input E V, which may be explained by an increased solubilized protein content in meat batters. The process-structure relationship determined can be used by manufacturers to predict product properties as a function of process parameters.

There is considerable interest in using structural design principles to control the rate and extent of lipid digestion within the human gastrointestinal tract (GIT) so as to develop functional foods to combat overweight and obesity. The purpose of this study was to examine the impact of a polysaccharide crosslinking enzyme (laccase) on the lipolysis of multilayered oil-in-water emulsions using a static in vitro GIT model. Primary (single-layered) fish gelatin-stabilized oil-in-water emulsions were prepared by microfluidization (10,000 psi, 5 passes, pH 4, 10 mM citrate buffer). Secondary (double-layered) emulsions were then prepared by electrostatically depositing sugar beet pectin on the gelatin-coated droplets. Laccase was then added to the double-layered emulsions to promote crosslinking of the adsorbed pectin molecules. Primary, secondary, and crosslinked secondary emulsions were then passed through an in vitro GIT model that included mouth, gastric, and intestinal phases. Emulsion stability to flocculation and coalescence within the GIT depended on layer composition and cross-linking. In particular, the single-layered emulsions were less stable to aggregation than the (crosslinked) double-layered ones. The rate and extent of lipid digestion did not greatly differ between crosslinked and non crosslinked multilayered emulsions. Free fatty acid profiles showed that the stability of emulsified oil droplets plays a major role in the rate and extent of lipid digestion, rather than the initial layer properties. These results suggest that directed destabilization of emulsified lipids using interfacial engineering approaches has potential for modifying lipid digestibility and/or the release of bioactive agents at specific sites within the GIT.

Microcrystalline cellulose (MCC) or carboxymethyl cellulose (CMC) can be used as potential fat replacers; both are non-digestible fibers. The objective of this study was, therefore, to assess the impact of added CMC/MCC on the microstructural/functional characteristics of beef patties. Therefore, low-fat beef patties were formulated with CMC/MCC at concentrations of 0.5–3.0 wt%. For this formulation, 10 wt% of the ground beef was replaced using a dispersion of CMC or MCC in water. The influence of the addition of MCC and CMC on the sensory characteristics, such as the texture, color, taste, flavor, and juiciness, of fried beef patties was evaluated by using a hedonic scale from 0 to 10 (5 = optimal). The confocal laser scanning microscopy (CLSM) measurements and sensory evaluation all indicated that addition of CMC (>1 wt%) led to destabilization of the microstructure, sensory quality and texture of fried beef patties, which, upon heating, could no longer be converted into a protein network with coarse meat and fat particles, a fact that was also revealed in the CLSM images. By contrast, the CLSM images prove that MCC was highly compatible with the matrix and improved the texture in the sensory evaluation with increasing concentration compared to the control. The best sensory evaluation achieved was with the beef patties containing 2 wt% MCC. Generally, hot samples containing MCC had more juiciness than the control and had a fat-like mouthfeel. Contrarily, CMC is not suitable as a fat replacer in concentrations more than 0.5 wt%.

Phenolic compounds in aqueous, saponin-rich soapbark tree (Quillaja saponaria Molina) extracts were qualitatively and quantitatively characterized by HPLC-PDA-MS(n) and NMR spectroscopy. (+)-Piscidic acid represented the major constituent (75-87% (w/w) of total phenolics) in all examined extracts (n = 4), ranging from 22.1 ± 0.1 to 34.0 ± 0.2 mg/g of dry matter (DM). Derivatives of p-coumaric acid were present at concentrations from 2.2 to 9.3 mg/g of DM (8.1-20.4% of total phenolics), whereas other phenolic constituents such as glucosyringic acid and vanillic acid derivatives accounted for less than 7% of total phenolics. Generally, all Quillaja extracts showed a highly similar but unique pattern, potentially being useful to authenticate Quillaja extracts in foods, cosmetics, and pharmaceutical formulations. Furthermore, the desired antioxidant activity as well as undesired browning reactions in the final product might also be explained by these phenolic compounds, which were identified for the first time in Q. saponaria extracts.

Polymers may alter the ability of surfactant micelles to solubilize hydrophobic molecules depending on surfactant–polymer interactions. In this study, isothermal titration calorimetry (ITC) was used to investigate the solubilization thermodynamics of an octane oil-in-water emulsion in anionic sodium dodecylsulphate (SDS), nonionic polyoxyethylene sorbitan monooleate (Tween 80), cationic cetyltrimethylammonium bromide (CTAB) surfactant micelles and respective complexes formed by these micelles and an anionic polymer (carboxymethyl cellulose). Results indicated that the oil solubilization in single ionic micelles was endothermic, while in nonionic micelles or mixed ionic/nonionic micelles it was exothermic. The addition of carboxymethyl cellulose did not influence the solubilization behavior in these micelles, but affected the solubilization capacities of these systems. The solubilization capacity of cationic micelles or mixed cationic/nonionic micelles was enhanced while that of nonionic or anionic micelles was decreased. Based on the phase separation model, a molecular pathway mechanism driven by enthalpy was proposed for octane solubilization in surfactant micelles and surfactant–polymer complexes.

Soy lecithin liposomes with incorporated grape seed extract (GSE) were prepared by high-pressure homogenization and coated with chitosan as a first layer and pectin as a second layer. The GSE and the uncoated and coated liposomes were mixed with native and heat-treated protein solutions of bovine serum albumin (BSA), whey protein isolate (WPI) and sodium caseinate (Na-caseinate) to investigate their interactions. Uncoated liposomes without GSE had the smallest particle size (34 nm); when GSE (0.1% w/w) was entrapped into liposomes; its size increased three-fold (102 nm). The particle sizes of chitosan-coated liposomes were 80 nm and 197 nm containing GSE as well as of pectin-chitosan-coated liposomes 227 nm and 157 nm, respectively. The ζ-potential changed from −23 over +49 to −31 mV (liposomes) and −26 over 46 to −29 mV after second layering (GSE-liposomes). Prior to centrifugation, the particle diameters of the chitosan-coated liposomes were smaller than in the other samples containing GSE and the ζ-potentials were the highest of all liposome–protein mixtures (∼45 mV). After centrifugation, the polyphenols and proteins could be recovered in the supernatant, which proved that chitosan-coated liposomes have reduced precipitation properties. Additionally, only small protein concentrations too low for determination with SDS-PAGE electrophoresis were found in the residues. Na-caseinate, however, was precipitated by the positively charged chitosan-coated liposomes due to more hydrophobic forces. GSE and negatively charged liposomes (uncoated liposomes and chitosan-pectin-coated liposomes) precipitated and sedimented the proteins. This was demonstrated by increased particle sizes and reduced protein contents in the supernatants.

The structurally related carotenoids β-carotene, γ-carotene, lycopene, rubixanthin, and β-cryptoxanthin differ in their terminal end groups and the presence or absence of a hydroxyl function. In this study, emulsions containing these carotenoids were subjected to an in vitro digestion to compare bioaccessibilities and antioxidant activities of the resulting micellar fractions. The bioaccessibility of lycopene and β-carotene was 28.6 ± 0.1% and 35.7 ± 0.3% respectively, γ-carotene bioaccessibility was between these values (32.7 ± 0.2%), while the bioaccessibility of rubixanthin (21.8%) and β-cryptoxanthin (28.8%) was significantly lower. The antioxidant activity of the corresponding micellized carotenoid fractions ranked as follows: rubixanthin ≥ lycopene > β-cryptoxanthin > γ-carotene > β-carotene for both the TEAC and FRAP assays. A similar trend was observed for the hexane-dissolved carotenoids. A negative linear correlation between bioaccessibility and FRAP (R2 = 0.7395) and TEAC (R2 = 0.9125) values was established. The presence of both open ψ-end groups and hydroxyl functions led to higher antioxidant activities as compared to the unsubstituted β-end group, presumably resulting in decreased stability during digestion and, thus, lowered bioaccessibility.

The effects of the interactions between polyphenolic substances (catechin/tannic acid) or plant extracts (grape seed/hibiscus extract), using each in three different concentrations (0.1–0.5%), and preheated whey protein isolate (Pre-HWPI) or Pre-HWPI–pectin complexes were studied at different pH (pH 3.2/5.2/6.1). Particle size, charge, protein precipitation capacity, and microscopic image were analyzed. The particle diameter (d43) in the solution containing polyphenols was slightly affected in a solution of Pre-HWPI at pH 3.2 or 5.2 and clearly increased at pH 6.1. The positive ζ-potential observed at pH 3.2 decreased slightly. The addition of catechin, grape seed extract and tannic acid, excluding hibiscus extract, induced the increase of negative charge at pH 5.2 and 6.1. The presence of polyphenols accelerated the protein precipitation of Pre-HWPI at pH 3.2 and 5.2 rather than at pH 6.1. The different types and concentrations of polyphenols present in Pre-HWPI–pectin complexes at pH 3.2 and 5.2 showed a small difference in particle size and charge. The addition of polyphenols to the polymer complexes at pH 6.1 influenced the increasing particle diameter, and the ζ-potential varied from −12.35 to −19.35 mV, depending on the different type and concentration of polyphenol. However, the sedimentation was only clearly observed in the sample containing 0.3 and 0.5% tannic acid. Furthermore, microscopic images depicted the similar structural appearance of the Pre-HWPI and Pre-HWPI–pectin complexes in the presence of polyphenols other than tannic acid. In summary, complexation of Pre-HWPI–pectin complexes reduces the protein precipitation with polyphenols and allows the use in complex food matrices.

The antimicrobial efficacy of three antimicrobials with different aqueous solubilities (sodium lactate > lauric arginate (Nα-lauroyl- l -arginine ethyl ester, LAE > methylparaben)) was evaluated. The antimicrobials were added individually, and as binary or ternary mixtures to emulsion type sausages. The antimicrobial efficacy was evaluated against Listeria innocua on the surface of sliced sausages over 24 days of storage at 6 °C. Growth over time was determined, and fitted to a model with a shifted logistic function for evaluation and comparison of antimicrobial effectiveness. The maximum added concentration of LAE (2.0 × 103 μg/g) delayed growth for 1 day. In contrast, lactate and methylparaben (40 and 4.0 × 103 μg/g, respectively) delayed growth for 18 and 7 days, respectively. Five different mixing ratios were investigated for the three different binary combinations: LAE/lactate, LAE/methylparaben and lactate/methylparaben. Results showed that efficacy could be enhanced through mixing of antimicrobials and that the type of antimicrobials as well as their mixing ratio influenced the antimicrobial efficacy of combinations. For ternary combinations, concentrations of two antimicrobials were kept constant while the concentration of the third preservative was varied. To this purpose LAE/methylparaben, LAE/lactate and lactate/methylparaben combinations with concentrations of 0.3/3.3, 0.3/16.7 and 6.6/2.7 × 103 μg/g, respectively, were combined with increasing concentrations of lactate, methylparaben and LAE, respectively. Results indicated that a further increase in activity is possible, albeit there appears to be a critical concentration of the third component below which the ternary combinations were less effective than the binary combinations. Overall our study suggests that combining antimicrobials with different solubilities is a promising approach to enhance shelf life of structurally-complex products such as emulsion type sausages.

Hypothesis This study examined the emulsifying properties of mixed surfactant systems of Quillaja saponins and food-grade co-surfactants (Na-caseinate, pea protein, rapeseed lecithin, and egg lecithin). We hypothesized to these mixtures may build mixed adsorption layers and thus enhance emulsion stabilization. Experiments Oil-in-water emulsions (10%, pH 7) were prepared with different concentrations of co-surfactants (0.1–5.0%) alone or mixed with Quillaja saponins (0.05 or 0.5%). Dynamic interfacial tension measurements were performed to characterize the behavior of the surfactants at an oil-water interface. Findings Low Quillaja saponin concentrations led to either no changes or substantial increases in particle sizes of protein stabilized emulsions, but d43-values decreased in lecithin stabilized emulsions at low lecithin concentrations. The dominating effect of Quillaja saponins at high concentrations led to formation of small droplets (d43 ≤ 2 µm) in all emulsions, except with 2.5% pea proteins. All co-surfactants showed synergistic or additive effects with respect to interfacial tension reductions upon addition of Quillaja saponins (except for egg lecithin with 0.005% Quillaja saponin addition). The results indicated a competing effect for saponin–protein interfaces, but formation of mixed saponin–lecithin interfaces, thus showing that the emulsion stabilization and interfacial properties can be tuned by specific binary surfactant mixtures.

In this study, the protection effect of black carrot extract on the stability of liposomes during storage was evaluated. The physical and chemical stability of the extract (0.4% w/w) including extract-loaded liposomes with various lecithin content (1%, 2%, and 4% w/w) were demonstrated. Z-average particle diameter and zeta potentials of liposomes were evaluated before and after 21 days of storage. The particle diameter of the samples was found to be lower than 50 nm after storage and no statistical change was determined (p 0.05). The liposomes with and without extract were visualized by transmission electron microscopy (TEM) after negative staining. The TEM images revealed that unloaded and extract-loaded liposomes are similar in size. The degradation of extract (30%-90%), phenolic content (10%-29%), and antioxidant capacity (4%-33%) of liposomes depending on lecithin content were also determined during storage to evaluate the biochemical stability. A hexanal analysis was performed to investigate the lipid oxidation in liposomes within 60 days. According to the results, the oxidation of polyunsaturated fatty acids may be inhibited with the addition of the extract to liposomes; however, lipid content should be limited according to the extract concentration. The highest protection on oxidation was observed in extract-loaded liposomes containing 1% lecithin. The study provided valuable data on the contribution of an anthocyanin addition to liposomes to overcome oxidation of unsaturated phospholipids.

This study aimed to prevent the phenomena of efflorescence formation on the surface of dry fermented sausages due to the complexation of efflorescence forming cations with phosphates. Efflorescence formation is a critical issue constituting a major quality defect, especially of dry fermented sausages. Different phosphates (di- and hexametaphosphate) were added (3.0g/kg) to the sausage batter. As a hypothesis, these additives should complex with one of the main efflorescence-causing substances such as magnesium. The formation of efflorescences was determined for dry fermented sausages without phosphate addition, with diphosphate, or hexametaphosphate addition during 8weeks of storage under modified atmosphere. The visual analyses of the sausage surface revealed high amounts of efflorescences for the control (42.2%) and for the sausages with added diphosphate (40.9%), whereas the sausages containing hexametaphosphate had significantly reduced amounts of efflorescence formation, showing only 11.9% efflorescences after 8weeks of storage. This inhibition was a result of strong complexation of hexametaphosphate with magnesium ions, thus preventing the diffusion of magnesium towards the sausage surface. This can be explained by the magnesium content on the sausage surface that increased by 163.9, 127.8, and 52.8% for the sausages without phosphate, diphosphate, and hexametaphosphate addition, respectively. The mass transport of lactate and creatine was not affected by phosphate addition. Isothermal titration calorimetry confirmed that, theoretically, 4.5g/kg of diphosphate or 2.8g/kg hexametaphosphate are required to complex 0.2g/kg magnesium ions naturally occurring in dry fermented sausages and, thus, the chosen overall phosphate concentration of 3.0g/kg was enough when adding hexametaphosphate, but not for diphosphate, to inhibit the efflorescence formation.

Lauric arginate (LAE), a cationic surfactant, is a highly potent food-grade antimicrobial that is active against a wide range of food pathogens and spoilage organisms. In compositionally complex environments, the antimicrobial activity of cationic LAE is likely to be impacted by its interactions with anionic components. The purpose of this study was to characterize the interactions between cationic LAE and an anionic biopolymer (high methoxyl pectin, HMP) using isothermal titration calorimetry (ITC), microelectrophoresis (ME), and turbidity measurements. ITC and ME measurements indicated that LAE bound to pectin, while turbidity measurements indicated that the complexes formed could be either soluble or insoluble depending on solution composition. In the absence of pectin, the critical micelle concentration (CMC) of LAE determined by ITC at 25 °C was 0.21% (w/v). The amount of LAE bound per unit amount of pectin decreased with increasing pectin concentration (from 1.5 to 0.5 g/g for 0.05 to 0.5 wt % pecti...

The interfacial and emulsion-forming properties of sugar beet extract (Beta vulgaris L.) were examined and compared to a Quillaja extract that is widely used within the food industry. We investigated the influence of extract concentration on surface activity at oil–water and air–water interfaces and on the formation of oil-in-water emulsions (10% w/w, pH 7). Sugar beet extract reduced the interfacial tension up to 38% at the oil–water interface, and the surface tension up to 33% at the air–water surface. The generated emulsions were negatively charged (ζ ≈ −46 mV) and had the smallest particle sizes (d43) of ∼1.3 μm at a low emulsifier-to-oil ratio of 0.75:10. Applying lower or higher extract concentrations increased the mean particle sizes. The smallest emulsions were formed at an optimum homogenization pressure of 69 MPa. Higher homogenization pressures led to increased particle sizes. Overall, sugar beet extract showed high surface activity. Furthermore, the formation of small emulsion droplets was suc...

Encapsulation is an established technique to protect sensitive materials from environmental stress. In order to understand the physical protection mechanism against oxidation, knowledge about the powder microstructure is required. Time domain-nuclear magnetic resonance (TD-NMR) has the potential to determine the surface oil (SO) and droplet size distribution by relaxation and restricted self-diffusion, respectively. The amount of SO, the retention and encapsulation efficiency are determined based on a lipid balance. The oil load of the initial powder and after SO removal is measured by TD-NMR. The results correlate with gravimetric and photometric references. The oil droplet size obtained by TD-NMR correlates well with static light scattering. The diameter of droplets in emulsions and dried powder both measured by TD-NMR, correlates (r = 0.998), implying that oil droplets embedded in a solid matrix can be measured. Summarising, TD-NMR allows analysis of the microstructure of encapsulated lipid powders, in a rapid, simple and non-destructive way.

The impact of emulsifier type (quillaja saponin, Tween 80, whey protein and casein) and antioxidant type (EDTA, ascorbic acid, catechin, alpha tocopherol, ascorbic acid palmitate) on the physical and chemical stability of lutein-fortified emulsions was investigated. Quillaja saponin produced emulsions with the best overall stability to droplet aggregation, creaming, and colour fading during storage at 45 °C for ten days. The impact of antioxidant type on the stability of lutein-fortified emulsions prepared using quillaja saponin was therefore investigated further. The extent of droplet aggregation and creaming was largely independent of antioxidant type. Surprisingly, most of the antioxidants promoted lutein degradation. Only ascorbic acid showed some ability to inhibit colour fading during storage, although EDTA had some inhibitory effects in the early stages of storage. This study suggests that lutein-enriched emulsions prepared using quillaja saponin as an emulsifier and ascorbic acid as an antioxidant may be the most suitable as delivery systems.

Black carrot anthocyanins are known to be relatively stable because they contain acylated anthocyanins. The degradation of vitamin C (l-ascorbic acid) on anthocyanins is a known fact in beverage systems. In this study, the effects of various liposomal systems, including black carrot extract (0.1%, 0.2%, 0.4% w/w) and lecithin (1%, 2%, 4% w/w), on the color and degradation of anthocyanin in different ascorbic acid (0.01%, 0.025%, 0.05%, 0.1% w/w) concentrations were examined via UV/VIS spectroscopy and visual control of the color. The physical characteristics of the liposomal systems resulted in particle diameters of 41-46 nm and zeta-potentials of (-23)-(-20) mV. The encapsulation efficiencies of the liposomal systems increased up to 50% with increasing lecithin concentrations. The encapsulation of black carrot extract in liposomes enhanced the color and stability of the anthocyanins during storage. This study showed that the degradation of anthocyanins due to ascorbic acid can be reduced by liposomes in aqueous solutions.

The optical properties of food emulsions play a key role in determining their perceived quality because they are the first sensory cue that many consumers receive. The purpose of the current study was to investigate the impact of a cross-linking enzyme (laccase) on the appearance of structured oil-in-water emulsions containing a lipophilic model colorant (Nile red). A layer-by-layer electrostatic deposition approach was used to prepare oil-in-water emulsions stabilized by interfacial protein-pectin complexes under acidic conditions (pH3.5, 10mM citrate buffer). Laccase (an oxidoreductase) was then added to the system, since this enzyme is often used to covalently cross-link interfacial biopolymer layers. The optical properties of the emulsions were monitored during storage using spectral reflectance to determine the L*a*b values, while the physical properties were monitored by measuring changes in droplet surface charge and particle size distribution. No changes in the size or charge of the droplets were observed during storage, indicating that the emulsions had good physical stability. In the absence of laccase, the emulsions were stable to colour fading, but in the presence of laccase rapid colour changes occurred (red to blue to white). These results have important implications for the formation of structured food emulsions containing certain types of food dyes.

Enzyme technologies can be used to create food dispersions with novel functional attributes using structural design principles. Enzymes that utilize food-grade proteins and/or polysaccharides as substrates have gained recent interest among food scientists. The utilization of enzymes for structuring foods is an ecologically and economically viable alternative to the utilization of chemical cross-linking and depolymerization agents. This review highlights recent progress in the use of enzymes to modify food structures, particularly the interfacial and/or bulk properties of food dispersions with special emphasis on commercially available enzymes. Cross-linking enzymes such as transglutaminase and laccase promote the formation of intra- and intermolecular bonds between biopolymers to improve stability and functionality, whereas various degrading enzymes such as proteases alter the native conformation of proteins, leading to self-assembly of hierarchically ordered colloids. Results of this bio-inspired approach show that rational use of structure-affecting enzymes may enable food manufacturers to produce food dispersions with improved physical, functional, textural, and optical properties.

Particulated complexes composed of oppositely charged biopolymers were incorporated into highly concentrated protein matrices as potential fat replacers and structuring agents. A multistep procedure was therefore utilized to generate process-stable complexes, which were subsequently embedded into emulsion-type sausages, whereas macro- and microstructural properties were then assessed. Firstly, stock WPI and sugar beet pectin solutions were mixed under neutral conditions (pH 7) at various biopolymer ratios r (2 : 1, 5 : 1, 8 : 1). Secondly, the pH of the biopolymer mixture was decreased to 3.5 to promote associative complexation. Thirdly, electrostatically attracted biopolymer particles were subjected to a heat treatment (ϑ = 85 °C, 20 min) to enhance their stability against superimposed stresses. Finally, fat-reduced emulsion-type sausages were fabricated containing stable WPI-pectin complexes. The results revealed that the heat treatment increased the pH-stability of the biopolymer complexes. In addition, textural and sensorial analysis demonstrated that the meat products became increasingly soft as the biopolymer ratio r increased. This effect was attributed to thermodynamic incompatibility between meat proteins and beet pectin. The results obtained from this study might have important implications for the fabrication of processed meat products with reduced fat levels.

Nanoemulsions are increasingly being used for encapsulation, protection, and delivery of bioactive lipids, however, their formation from natural emulsifiers is still challenging. We investigated the impact of alcohol on the formation and stability of protein-stabilized oil-in-water nanoemulsions prepared by high-pressure homogenization. The influence of different alcohols (ethanol, 1-propanol, and 1-butanol) at various concentrations (0-25% w/w) on the formation and stability of emulsions stabilized by sodium caseinate, whey protein isolate, and fish gelatin was investigated. The mean particle diameter decreased with increasing alcohol concentrations from 0 to 10%w/w, but extensive droplet aggregation occurred at higher levels. This phenomenon was attributed to enhanced protein-protein interactions between the adsorbed emulsifier molecules in the presence of alcohol leading to droplet flocculation. The smallest droplets (d

The purpose of this study was to investigate the potential of a saponin-rich extract of Quillaja saponaria to replace bile salts in the surfactant formulations for stabilization of nanostructured lipid carriers (NLC). The influence of Quillaja extract and/or high-melting lecithin at different concentrations on physical and oxidative stability was evaluated in (i) NLC containing tristearin and ω-3 fish oil, (ii) ω-3 fish oil-in-water emulsion, and (iii) solid lipid nanoparticles (SLN) containing tristearin. Best physical, polymorphic and oxidative stability of NLC were achieved with a surfactant combination of 2.4% (w/w) Quillaja extract and 0.6% (w/w) high-melting lecithin. The results showed that encapsulation of ω-3 fish oil into NLC inhibited the formation of lipid hydroperoxides, propanal and hexanal by 72, 53 and 57%, respectively, compared to the fish oil-in-water emulsion prepared with the same surfactants. This indicated that the low oxidation observed in NLC cannot be due to potential antioxidative effects of the surfactant combination itself. Evidence is accumulating that tristearin is able to form a protective shell around the ω-3 fish oil, when crystallization is induced via high-melting phospholipids in the solidified interfacial layer.

Native casein micelles were treated (incubated) with vitamin D2 at different hydrostatical pressures (0.1, 200, 400, and 600MPa) and temperatures (10-50°C) in order to load the vitamin. Pressure induced the release of αs-, β- and κ-casein and calcium from the micelle into the soluble phase. During the pressure stable reassembled micelles were created due to a structural rearrangement of hydrophobic interactions between the hydrophobic domains of the caseins and vitamin D2. Treatment at 600MPa and 50°C increased the loading of vitamin D2 per casein from 2.2±0.2μg/mg (native sample) to 10.4±0.2μg/mg. The reassembled micelles presented an average hydrodynamic diameter of 272±10nm and contained 8.1, 10.3 and 0.8mg of α-, β- and κ-casein, respectively, per 100mg casein.