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Purpose: Present study envisaged the impact of sodium substitution with potassium @ 1:1 and 1:3 on the release of ACE inhibitory peptides in Cheddar cheese during storage (4 ℃/9 months). Methods: Control (NaCl 2.5 g/100gm) and sodium substituted Cheddar cheeses (1NaCl:1KCl and 1NaCl:3KCl) were prepared studied for the in vitro angiotensin converting enzyme (ACE) inhibitory activity during storage period of 9 months. Cheddar Cheeses (5th month) with potent ACE inhibitory activity were further assessed for the peptides identification via RP-HPLC and LC-MS/MS technique. The obtained peptides were screened for bioactivity and potential bioactive peptides were selected for molecular docking for identifying the active sites on ACE enzyme for ACE inhibitory peptides. Results: Among all identified peptides, 2, 2 and 6 peptides were selected as potentially bioactive via peptide ranker in control, 1NaCl:1KCl and 1NaCl:3KCl Cheddar cheeses respectively. Molecular docking revealed that QEPVLGPVRGPFPI peptide in 1NaCl:3KCl Cheddar cheese showed the highest number of hydrogen bonding (binding energy −10.2) Tyr62, Asn66, Asn70, Arg124, Tyr135, Asn211, Ser219, Ala356, Glu403, Ser516 and Ser517 amino acid residues of ACE. Conclusion: The salt substitution at higher level (1:3) resulted in the increased number of ACE inhibitory peptides than the control Cheddar cheese during ripening. Therefore salt substitution in cheese can be a healthier approach for minimizing sodium level in the diet. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate changes of physicochemical and functional properties of the processed cheeses (PCs) made with Cheddar (PC1), Mozzarella (PC2) and both of them at a ratio of 1:1 (PC3) during storage at 4 °C for 4 months. The results showed that the type of natural cheese used affected the composition of PCs with lower fat content in PC2 due to the lower fat content of Mozzarella cheese used. PC2 with lower fat content showed decreased meltability and oil leakage compared with PC1 and PC3. The stretchability of all the samples significantly (P < 0.05) decreased during storage, and PC1 showed lower stretchability. This was confirmed by increased protein hydrolysis of all the samples during the storage with a higher level of proteolysis in PC1, leading to decreased stretchability of PCs. Further low-field nuclear magnetic resonance analysis indicated more entrapped water in cheese due to moisture migration into the cheese matrix that might squeeze the fat globules to aggregate, causing more fat leakage during later stages of storage. This was evidenced by microstructural analysis showing different extents of increase in fat particle sizes and decrease in free serum in all the PC samples over the storage time. Therefore, the present study provides further understanding of the mechanism of quality change of PC during refrigerated storage as affected by proteolytic properties and composition of natural cheese used. [ABSTRACT FROM AUTHOR]

Cheese fermentation and flavour formation are the result of complex biochemical reactions driven by the activity of multiple microorganisms. Here, we studied the roles of microbial interactions in flavour formation in a year-long Cheddar cheese making process, using a commercial starter culture containing Streptococcus thermophilus and Lactococcus strains. By using an experimental strategy whereby certain strains were left out from the starter culture, we show that S. thermophilus has a crucial role in boosting Lactococcus growth and shaping flavour compound profile. Controlled milk fermentations with systematic exclusion of single Lactococcus strains, combined with genomics, genome-scale metabolic modelling, and metatranscriptomics, indicated that S. thermophilus proteolytic activity relieves nitrogen limitation for Lactococcus and boosts de novo nucleotide biosynthesis. While S. thermophilus had large contribution to the flavour profile, Lactococcus cremoris also played a role by limiting diacetyl and acetoin formation, which otherwise results in an off-flavour when in excess. This off-flavour control could be attributed to the metabolic re-routing of citrate by L. cremoris from diacetyl and acetoin towards α-ketoglutarate. Further, closely related Lactococcus lactis strains exhibited different interaction patterns with S. thermophilus, highlighting the significance of strain specificity in cheese making. Our results highlight the crucial roles of competitive and cooperative microbial interactions in shaping cheese flavour profile. Cheese fermentation and flavour formation are the result of complex biochemical reactions driven by the activity of multiple microorganisms. Here, the authors identify microbial interactions as a mechanism underlying flavour formation in Cheddar cheese. [ABSTRACT FROM AUTHOR]

The addition of ultrafiltered (UF) milk retentate is known to impact milk properties during mozzarella and cheddar cheese production, but the effect during cream cheese production is less well understood. Little is known about the impact of UF retentate on the intermediate stages of manufacture, such as protein assembly and the formation of hydrated acid gel structures. Here, milk prepared for cream cheese manufacture using a concentration factor of 2.5 or 5 had a similar particle size distribution to unconcentrated cheese milk after homogenization but increased viscosity and a slower rate of acidification, which could be altered by increasing starter culture concentration. The acid gels formed contained more protein and fat, resulting in a higher storage modulus, firmness, and viscosity. A denser microstructure was observed in acid gels formed with UF retentate addition, and quantitative two- or three-dimensional analysis of confocal images found a greater volume percentage of protein and fat, decreased porosity, and increased coalescence of fat. The mobility of water, as assessed by proton nuclear magnetic resonance, was reduced in the dense UF gel networks. Water movement was partially obstructed, although diffusion was possible between interconnected serum pores. These insights improve our understanding of acid gel formation. They can be used by manufacturers to further optimize the early and intermediate stages of cream cheese production when using concentrated milk to reduce acid whey production and lay the foundation for larger pilot scale studies of intermediate and final cream cheese structure. [ABSTRACT FROM AUTHOR]

Neuroimaging studies that focus on taste, odor, and their interactions can specify their capability to elicit brain regions responsible for flavor perception and reward. Such information would be useful for formulating healthy food products, such as low salt food. In this study, a sensory experiment was conducted to investigate the capability of cheddar cheese odor, monosodium glutamate (MSG), and their interactions to enhance saltiness perception and preference of NaCl solutions. The activated brain areas in response to odor-taste-taste interactions were then investigated using an fMRI study. The results of the sensory tests showed that saltiness and preference of NaCl solutions were enhanced in the presence of MSG + cheddar cheese odor. According to the fMRI study, the stimulus with a higher salty rate activated the rolandic operculum, and the stimulus with a higher preference activated the rectus, medial orbitofrontal cortex, and substantia nigra. Moreover, the activation of multiple regions, such as the orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), temporal pole, and amygdala was observed in response to (cheddar cheese odor + MSG + NaCl) minus (odorless air + NaCl). [ABSTRACT FROM AUTHOR]

The interest in active packaging for extending food shelf life has increased lately. Moreover, the negative impact of synthetic plastic wastes on the environmental motivated the researchers to seek for bio-based alternatives. In this context, active packaging film made of a composite composed of Lepidium sativum extract (LSE), polyvinyl alcohol (PVA), and a fixed amount of hyperbranched polyamide amine (PAMAM) were prepared. The chemical, thermal, and mechanical properties of the film were investigated. Moreover, we examined the extract's constituents and antioxidant properties. Cheddar cheese samples were coated with films of different compositions. The samples coated with active packaging films showed a longer preservation time of up to 4 weeks compared to other samples, which noticeably deteriorated. The films showed potent antimicrobial activity against five food-borne bacteria: three gram-negative bacteria including Escherichia coli O157.H7, Pseudomonas aeruginosa, and Salmonella Typhimurium, and two gram-positive bacteria, Listeria monocytogenes, and Staphylococcus aureus. Applying PVA films containing LSE improved the microbiological quality and delayed the visible decay of cheddar cheese. The oxidizability of the fat extracted from different cheese samples was 0.40–0.98, confirming oxidation resistance. Finally, cheese samples coated with treated films were protected from forming trans fats compared to other samples, demonstrating the effectiveness of modified films as antioxidant, antimicrobial, and food-preserving packaging. [ABSTRACT FROM AUTHOR]

Liquid smoke is a liquid flavouring and customer favourite alternative to traditional food smoking. In this study, fast pyrolysis and selective condensation technologies were used to produce liquid smoke from kanuka (Kunzea ericoides) wood. Chemical analysis showed the abundant compounds in kanuka wood liquid smoke were creosol, guaiacol, syringol, and 4-ethylguaiacol in phenol groups. Liquid smoking of cheddar cheese was compared with and cold smoking method. Liquid smoked and cold-smoked cheddar cheese were analysed for their effects on the texture profile, colour change and shelf life of the cheese. Principal component analysis was employed to classify smoked cheese samples and interpret the correlation of treatment conditions and cheese characteristics. Liquid smoking treatment showed the advantages of rapidly processing and altering cheese characteristics. During storage, the reactions between smoke compounds and cheese led to further changes in cheese characteristics. Liquid smoking and cold smoking both showed strong antimicrobial activities, which could prolong the shelf life for at least 8 weeks for ambient storage. [ABSTRACT FROM AUTHOR]

Cheddar cheese proteolysis were accelerated employing Penicillium candidum PCA1/TT031 protease into cheese curd. In the present study, several of the significant factors such as protease purification factor (PF), protease concentration and ripening time were optimized via the response surface methodology (RSM). The ideal accelerated Cheddar cheese environment consisted of 3.12 PF, 0.01% (v/v) protease concentration and 0.6/3 months ripening time at 10 °C. The RSM models was verified to be the most proper methodology for the maintain of chosen Cheddar cheese. Under this experimental environment, the pH, acid degree value (ADV), moisture, water activity (aw), soluble nitrogen (SN)%, fat and overall acceptability were found to be 5.4, 6.6, 35%, 0.9348, 18.8%, 34% and 13.6, respectively of ideal Cheddar cheese. Furthermore, the predicted and experimental results were in significant agreement, which confirmed the validity and reliability of the suggested method. In spite of the difference between the ideal and commercial Cheddar cheese in the concentration of some of amino acids and free fatty acids, the sensory evaluation did not show any significant difference in aroma profile between them. [ABSTRACT FROM AUTHOR]

Emergence of food borne pathogens and multidrug resistant organisms has enforced the screening of natural antimicrobial compounds. Bacteriocins are ribosomally synthesized natural antimicrobial peptides produced by numerous bacteria. These antimicrobial peptides are gaining more attention as alternative therapeutics in pharmaceutical industry as next-generation antibiotics targeting the multi-drug resistant pathogens and as a bio preservative in food industry. The current study is aimed to purify and characterize a broad spectrum bacteriocin (Bac-IB45) with the determination of its plausible mode/mechanism of action. In this research, Bac-IB45 from Lactobacillus plantarum KIBGE-IB45 was 41.71-fold purified with the molecular mass of 20.5 kDa estimated using tricine SDS-PAGE. This bacteriocin is highly thermostable and pH stable in nature. It also exhibited stability against various metal ions, surfactants and organic solvents. Purified Bac-IB45 showed broad antimicrobial potential against various multidrug resistant, food borne bacterial and fungal pathogens. However, Bac-IB45 was found to be sensitive to various proteolytic enzymes. The time-kill assay of Bac-IB45 and scanning electron microscopic analysis revealed the bactericidal mode/mechanism of action against Listeria monocytogenes ATCC 7644. This unique Bac-IB45 with broad spectrum of inhibition and bactericidal mode of action could be used as a natural food preservative and as alternative therapeutics to solve the unrestrained problems of industries. [ABSTRACT FROM AUTHOR]

Cheese is a fermented dairy product that is made from animal milk and is considered to be a healthy food due to its available nutrients and potential probiotic characteristics. Since the microbes in the cheese matrix directly contribute to the quality and physicochemical properties of cheese, it is important to understand the microbial properties of cheese. In this study, Cheddar cheeses produced on three different dates at the Arbuthnot Dairy Center at Oregon State University were collected to determine the microbial community structure. A total of 773,821 sequencing reads and 271 amplicon sequence variants (ASVs) were acquired from 108 samples. Streptococcus and Lactococcus were observed as the most abundant ASVs in the cheese, which were used as the starter lactic acid bacteria (SLAB). Escherichia coli was detected in the raw milk; however, it was not detected after inoculating with SLAB. According to an alpha diversity analysis, SLAB inoculation decreased the microbial richness by inhibiting the growth of other bacteria present in the milk. A beta diversity analysis showed that microbial communities before the addition of SLAB clustered together, as did the samples from cheese making and aging. Non-starter lactic acid bacteria (NSLAB) were detected 15 weeks into aging for the June 6th and June 26th produced cheeses, and 17 weeks into aging for the cheese produced on April 26th. These NSLAB were identified as an unidentified group of Lactobacillaceae. This study characterizes the changes in the Cheddar cheese microbiome over the course of production from raw milk to a 6-month-aged final product. Key points: • 271 ASVs were acquired from cheese production from raw milk to 6-month aging. • Addition of SLAB changed the microbial diversity during Cheddar cheese making procedure. • NSLAB were detected more than 15 weeks after aging. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the feasibility of using near-infrared hyperspectral imaging (NIR-HSI) technique for classifying commercial Cheddar cheeses from different brands. Three classification models including a probability based partial least squares discriminant analysis (PLSDA), linear discriminant analysis (LDA) and successive projections algorithm (SPA)–LDA were used to discriminate four brands of Cheddar cheeses. A simple sample ranking method was used to improve the performance of these models. The generalisation abilities of the PLSDA, LDA and SPA–LDA models for the classification of new batch cheeses were investigated. The optimal number of PLS components was 24 for PLSDA, while the optimal SPA selected wavelengths was 105 for SPA–LDA. The results showed that PLSDA built by hyperspectral data was the most suitable model for brands classification with correct classification rate of 86.67%, and SPA–LDA had better performance than LDA with corresponding correct classification rates of 83.33% and 76.67%, respectively. As a comparison, models built by physical data (texture and colour) achieved poor classification results (< 65% for test set). The current result revealed that HSI technique is better and faster than conventional cheese classification methods. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

The aim of the present study was to incorporate potato for the development of processed cheese rich in carbohydrates with low fat content and to minimize the cost without affecting the overall quality. A blend of young and old Cheddar cheese was used in the preparation. Boiled and mashed potatoes were incorporated at a level of 20, 30 and 40% and the effect on the physico-chemical, textural and sensory properties were evaluated. Results showed that with the increased level of potato incorporation into the processed cheese, moisture content increased whereas fat and protein content decreased. On textural properties no significant difference (p > 0.05) was found till 20 and 30% incorporation, but at 40%, hardness and gumminess was significantly (p < 0.05) lower than the control. On sensory properties, flavour intensity decreased with the increased level of potato incorporation but was non-significant (p > 0.05) till 30% level but at 40% it was significantly lower (p < 0.05) than the control. Cheese samples with 40% potato level were found to be very soft and sticky but those with 20 and 30% were found to have a smooth firm body and a better mouth feel. Colour and appearance was almost similar in all samples. Our results suggest that an acceptable quality processed cheese can be made with up to 30% potato incorporation. However, with slight modification of processing parameters, more than 30% can also be incorporated without any adverse effect on the overall quality of the processed cheese. [ABSTRACT FROM AUTHOR]

In view of their growing importance in human nutrition, incorporation of oats and cheese during the manufacture of short-dough type biscuits was studied. Rolled oats were incorporated at 25, 35 and 45 % of refined wheat flour in short-dough type biscuit formulation. Cheddar and processed cheese were used for flavouring purpose at three levels each, viz. 30, 40 and 50 % on flour basis. The dough exhibited less firmness on oats incorporation as indicated by lower firmness value (21.73 N) as against 25.05 N for control dough measured by Texture Analyser. Addition of cheese to the 25 % oat incorporated dough further reduced its firmness and altered its viscoelastic characteristics. Baking conditions for the oats and cheese incorporated biscuits were optimized as 165 °C for 25-27 min. Sensory evaluation results revealed that the biscuit made from 25 % oat incorporated dough scored highest in most of the sensory attributes including overall acceptability. Cheddar cheese and processed cheese levels were optimized at 30 and 40 % in oats-incorporated dough based on the sensory analysis of biscuits prepared from the dough samples. The moisture and β- glucan contents were 3.93 % and 0.62 %; 4.32 % and 0.60 % for cheddar cheese and processed cheese added biscuits, respectively. The spread ratios were higher in cheese incorporated biscuits than in oat incorporated biscuits. It was concluded that good quality cheese flavoured biscuits can be prepared by incorporating rolled oats in biscuit formulation along with cheddar or processed cheese. [ABSTRACT FROM AUTHOR]

There is an increasing focus on the development of cheese with reduced-fat and salt contents, owing to greater consumer focus on the profiling and intake management of nutrients. The current study evaluated the effects of reducing fat and salt, each by 30 and 50%, on the composition, microbiological and biochemical characteristics of Cheddar-style cheese over a 270-day ripening period. Reducing salt from 1.9 to 1.2 or 0.9% ( w/ w) significantly increased ( P < 0.05) moisture, lactic acid, lactic acid-to-protein ratio and water activity and reduced the mean level of residual lactose and starter culture die-off during ripening. Reducing fat from 33 to 22 or 16% ( w/ w) resulted in significant increases in moisture, protein and lactic acid and reductions in salt-in-moisture, moisture-in-non-fat substances and lactic acid-to-protein ratio. Lactose content, pH and water activity were significantly affected by the interaction of fat and salt. The pH changed during the course of ripening, decreasing in full-fat full-salt cheese, increasing in half-fat reduced-salt and half-fat half-salt cheeses and remaining constant in other cheeses with different fat and salt levels. After 270 days of maturation at 8 °C, the full-fat full-salt cheese had lower concentrations of lactic acid and free amino acids and pH and a higher lactic acid-to-protein ratio than the reduced-fat reduced-salt or half-fat half-salt cheeses. The current results, together with a follow-on communication on the impacts of reducing fat and salt on physical and sensory properties, will provide a knowledge platform which should facilitate the commercial development of reduced-salt, reduced-fat, dry-salted cheeses. [ABSTRACT FROM AUTHOR]

Rennet is an important ingredient in Cheddar cheese manufacturing and both the type used and the concentration applied can affect the ripening process. In this work, reduced-fat Cheddar cheese was produced using different concentrations of microbial rennet (Hannilase; 0.026, 0.052 and 0.150 international milk clotting units (IMCU).g of milk) as well as recombinant camel chymosin (0.052 IMCU.g of milk). The composition of the resulting cheeses was not statistically different, but the ratio of pH 4.6 soluble nitrogen/total nitrogen (pH 4.6-SN/TN) increased significantly with increasing Hannilase rennet concentration. This ratio was also significantly lower in the cheese made with recombinant camel chymosin at a similar rennet concentration. Microstructural, biochemical and textural changes in the cheese were also monitored during ripening. The gel made with a high rennet concentration was qualitatively more porous but these changes in porosity were not reflected in the freshly pressed cheese. After 31 weeks of ripening, the cheese made with recombinant camel chymosin had a thicker protein network compared to the cheese made with microbial rennet (Hannilase), possibly due to lower proteolysis. Most of the Hannilase rennet was lost to the whey when the rennet was increased above the concentration of 0.052 IMCU.g of milk. A lower concentration of Hannilase rennet may prove beneficial, as the texture was not significantly affected at the end of the observed ripening period. Recombinant camel chymosin may potentially be used as a substitute for products requiring lower proteolysis during ripening. However, the texture of this cheese was harder than the cheese made with Hannilase rennet at the end of the ripening period. [ABSTRACT FROM AUTHOR]

Changes in the stress relaxation behavior of Cheddar cheese was measured at different storage temperatures (5-25ºC). A 3-element Maxwell model was used for calculation of instantaneous elastic, elastic, and viscous constants. As the storage temperature increased from 5 to 25ºC, rheological properties of instantaneous and equilibrium stresses, and instantaneous elastic, elastic, and viscous constants decreased. A master curve was constructed based on moving each stress relaxation curve horizontally on the basis of reference temperature (15ºC) with shift factors. The master curve of Cheddar cheese had a linear temperature dependency. The modulus of elasticity decreased as the storage temperature increased. The predicted shelf life and activation energy of Cheddar cheese at different storage temperatures were calculated using the Williams-Landel-Ferry equation. The activation energy was 50.25 kcal/mol, and the expected shelf life was 15 times longer when stored at 5ºC than at 15ºC. [ABSTRACT FROM AUTHOR]

Casein and whey protein concentrate (WPC) films, plasticized with glycerol and sorbitol independently, were prepared by casting. The film thickness, water vapour and oxygen permeation and tensile and moisture sorption properties of the films were determined. The tensile strength (TS), tensile strain (TE) and elastic modulus (EM) of the films ranged from 0.71 to 4.58 MPa, 19.22 to 66.63 % and 2.05 to 6.93 MPa, respectively. The film properties were influenced by the type of biopolymer (casein and whey protein concentrate), plasticizer and its concentration. Increasing the plasticizer concentration, increased the film thickness, TE and water vapour permeability (WVP), but decreased the TS and EM. As the concentration of plasticizer increased to the highest level, the film thickness increased from 0.168 to 0.305 mm for glycerol-plasticized films and from 0.251 to 0.326 mm for sorbitol-plasticized films. The film thickness increased because the amount of plasticizer in the film network increased and the amount of biopolymer remained same. Casein films showed superior tensile properties as compared to WPC films. The WVP of both casein and WPC films lied between 3.87 and 13.97 g.mm./(m.h.kPa). The moisture sorption isotherms of both films were typical of high-protein material, and were adequately described by the GAB model. The oxygen permeability of casein films was relatively lower than that of WPC films, regardless of the plasticizer used. The sensory data revealed that the organoleptic quality of Cheddar cheese was unaffected by milk-protein film packaging. [ABSTRACT FROM AUTHOR]

The effect of varying the milk protein concentration using low-concentration factor ultrafiltration retentate (~3.7, 4, 4.8 and 5.8 % w/ w protein) on Cheddar cheese during ripening was investigated. Quantitative analysis of the fat microstructure observed using confocal laser microscopy showed that the effect of the milk protein or time on the microstructure of the fat was minimal. Analysis of the protein sections showed a possible decrease in the branching of the protein network with time, as denoted by the smaller number of vertices, which correlated significantly with the level of trichloroacetic-soluble nitrogen ( r = −0.66, P < 0.001) as well as the cohesiveness of the cheese ( r = 0.70, P < 0.001). The hardness was different in cheese made with different milk protein concentrations during ripening. At week 26 of the maturation period, the cheeses made from the 4.8 and 5.8 % w/ w milk protein were significantly harder than the cheese with no ultrafiltration retentate (UF) addition, which might appeal for particular end uses and selected consumers. This observation correlates with the thicker protein network seen for the cheeses with higher milk protein observed in the cryo-scanning electron microscopy images. Our findings indicate that milk protein concentration has little effect on the cheese microstructure and texture especially when an adequate ripening period is provided, suggesting that high cheese manufacturing throughput may be obtained via this method if maturation is adequate. [ABSTRACT FROM AUTHOR]

Lactobacilli have been used as adjunct cultures in the manufacture of different cheeses with the objective of accelerating ripening and/or improving cheese quality, but no studies have been conducted with strains from non-dairy origins. A miniature cheddar-type cheese model was used to screen ten dairy and non-dairy Lactobacillus plantarum, Lactobacillus paraplantarum and Lactobacillus pentosus strains for their performances as adjuncts in cheese manufacture. All strains were able to grow and survive in the cheese environment and produced only minor, although statistically significant, changes in gross cheese composition. Adjuncts affected secondary proteolysis causing differences in the levels of free amino groups, total free amino acids and reversed-phase HPLC (RP-HPLC) profiles of pH 4.6-soluble extract. Three strains were selected on the basis of differences in proteolysis pattern and used in a pilot-plant production of cheddar cheese, which was ripened for 180 days. The results confirmed that use of L. plantarum adjuncts significantly affected secondary proteolysis as measured by free amino acid production with minor impact on gross composition and primary starter performance, but the impact on RP-HPLC profiles of pH 4.6-soluble extracts was not statistically significant. The use of a strain originally isolated from olive brine fermentation, L. plantarum P1.5, resulted in significantly improved preference scores over the control. [ABSTRACT FROM AUTHOR]

Homogenisation of milk breaks the protective fat globule membrane, allowing access of indigenous lipoprotein lipase and hydrolysis of free fatty acids (FFA) from triglycerides. The use of homogenisation in cheesemaking is limited due to the deleterious impact on cheese quality. The objective was to investigate the effects of a pre-processing routine (homogenisation of raw milk, incubation and pasteurisation) on the resultant cheese. Pilot- and laboratory-scale Cheddar cheeses were produced where raw bovine milk was homogenised at various pressures (0, 5 and 10 MPa in the pilot-scale and 0, 5, 10, 15, 20 and 25 MPa in the laboratory-scale trial), incubated at 37 °C for 1 h and batch-pasteurised at 63 °C for 30 min. A control milk was not homogenised. Acid degree value increased with increasing homogenisation pressure. Moisture and salt contents were higher in cheeses made with milk homogenised at 5 and 10 MPa, as was pH. The cheese made from milk homogenised at 10 MPa contained the highest level of FFA initially and throughout ripening. Breakdown of α-casein was more extensive in cheese made from non-homogenised milks and breakdown of β-casein was more extensive in homogenised milk cheeses. The use of low-pressure homogenisation in a controlled pre-processing routine may be suitable for cheesemaking; however, further investigation into the effects of the pre-treatment and effects on cheese microstructure and sensory properties is warranted. [ABSTRACT FROM AUTHOR]

Green tea polyphenols are known for their antioxidant properties. They also interact with milk proteins, suggesting good retention in the cheese matrix. The objective of this study was to evaluate the effect of green tea extract (GTE) enrichment on the organoleptic and physicochemical properties of Cheddar-type cheese during storage. GTE was added to milk at concentrations of 0, 1, and 2 g.kg and cheeses were produced on a pilot scale. An average polyphenol retention coefficient of 0.63 was obtained in cheese. Total protein, fat, micellar calcium content, and yield of cheese were not significantly affected by GTE addition ( P > 0.05). However, cheese moisture decreased by 1.9% with the addition of GTE at a concentration of 2 g.kg of milk. Enrichment with GTE significantly affected the color of Cheddar-type cheese ( P ≤ 0.05). A loss of lightness ( L* value) and an increase in redness ( a* value) and yellowness ( b* value) were observed. Cheeses enriched with GTE showed higher hardness and a loss of cohesiveness and springiness, which is indicative of alteration of the paracasein matrix. Cheese sensory properties were evaluated by trained panelists using a ranking test. A decrease in the typical Cheddar flavor and an increase in the overall flavor intensity and the astringency of cheese were observed with the addition of GTE. The addition of GTE at a concentration of 1 or 2 g.kg of milk increased the antiradical activity of cheese by 25 and 44%, respectively ( P ≤ 0.05). GTE enrichment of Cheddar-type cheese could result in new products with increased health benefits. [ABSTRACT FROM AUTHOR]

Fat replacers can be used to improve the sensory and functional properties of reduced-fat cheeses. The effect of gum tragacanth (GT) on the rheological, functional and sensory properties of half-fat and full-fat Cheddar cheese during ripening was investigated. Four Cheddar-style cheeses were made in triplicate: full-fat control (FFC), half-fat control (HFC), full fat + GT (FFGum) and half fat + GT (HFGum). Cheesemilk for the latter two cheeses was supplemented with GT at a level of 0.05% ( w/ v); all cheeses were ripened at 8 °C for 10 months. Moisture and moisture-to-protein ratio were increased by GT addition. GT addition resulted in decreased pH in both FFGum and HFGum cheeses during ripening, especially the FFGum cheese. GT appeared to affect proteolysis only in the FF cheeses. GT was successful in decreasing hardness and springiness values during ripening. GT increased meltability in the FFGum cheese and to a lesser extent in the HFGum cheese in late ripening. An increase in opaqueness was also observed due to GT addition regardless of fat level. Dynamic small amplitude oscillatory rheology showed a depression in LT and an increase in G′ at 75 °C caused by GT at 7 months of ripening. GT did not appear to have any impact on starter bacteria and NSLAB counts. Results from a consumer ranking preference test showed that the GT was not successful in fully mimicking the sensory properties of the FFC cheese. These results suggest that GT appears more suited to enhancing the textural and functional properties of half-fat Cheddar cheese than its sensory properties. [ABSTRACT FROM AUTHOR]

The probiotic adjunct Lactobacillus plantarum K25 was inoculated into milk to produce probiotic cheese. The effect of Lb. plantarum K25 on cheese composition, microbiological growth and survival during the manufacturing and ripening period, primary and secondary proteolysis during cheese ripening, and the in vivo cholesterol-lowering ability of the probiotic cheese were investigated. The results showed that the use of adjunct Lb. plantarum K25 in Cheddar cheese did not affect the cheese components including moisture, protein, fat, salt content and the pH value of cheese. During the whole ripening period, the probiotic adjunct maintained its viability, suggesting the effectiveness of Cheddar cheese as a vehicle for delivery of probiotic bacteria. No significant differences were observed in water-soluble nitrogen, 70 % ethanol-soluble nitrogen, 5 % phosphotungstic acid-soluble nitrogen, free amino acids and urea-PAGE patterns between the control and probiotic cheeses. Assessment of the in vivo cholesterol-lowering property of cheese with Lb. plantarum K25 showed that the levels of serum total cholesterol, low-density lipoprotein cholesterol and triglycerides decreased significantly, and the level of serum high-density lipoprotein cholesterol increased in mice fed with the probiotic cheese. The results indicated the potential function as a dietary item of the probiotic cheese with Lb. plantarum K25 to reduce the risk of cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Reduction of salt in ripened cheese presents an industry challenge due to its profound role in flavour and texture development. This study investigated the biochemical impact of varying the salt concentration in Cheddar cheese while maintaining the moisture content constant, with particular emphasis on proteolysis. Cheeses containing 0.9, 1.3, 1.8 and 2.4 % ( w/ w) salt and 37.7 ± 0.2 % ( w/ w) moisture were manufactured by parallel adjustment of the curd grain size, cooking temperature and time, cheddaring, curd chip size and rate of salting and analysed over the course of 270 days ripening. Salt reduction affected chymosin and starter lactocepin activities to accelerate casein degradation and accumulate derived peptides at rates correlating positively or (mostly) inversely with salt concentration. The kinetics of α-CN(f1-23) and N-terminal peptides produced thereof and of β-CN(f193-209) were studied in detail. Plasmin activity was affected by cooking treatment and (small) pH differences during ripening but appeared limited overall, due to low levels of pH. Starter lysis showed a strong positive dependency on the salt concentration, and resultant lower contents of free amino acids upon salt reduction were evident. In essence, salt reduction caused a marked decrease in the ratio of peptidase to proteinase activity. Remedies to counterbalance this ratio were discussed in order to avoid excessive accumulation of bitter peptides and promote the stage of maturity. Salt variation left cheese identity unaltered, and the concept of moisture equalisation was proposed as an initial measure to produce high-quality salt-reduced Cheddar. [ABSTRACT FROM AUTHOR]

Despite substantial research, it is still difficult to produce high quality reduced-fat Cheddar cheese. The objective of this study was to investigate how two coagulants, bovine chymosin (BC) and camel chymosin (CC) having different proteolytic activities and two starter cultures, an O-culture (O) and a thermophilic strain of Lactobacillus plus O-culture (OLb) having different abilities to release amino acids, contribute to the structure and flavour development in reduced-fat Cheddar cheese. Cheeses manufactured using the four combinations of coagulants and cultures were analysed during a 28-week ripening period for the composition of casein, peptides, free amino acids, rheological properties and for sensory properties at end of ripening. Cheeses with CC, showed less extensive primary proteolysis, lower levels of bitterness and higher stress at fracture, which correlates to a harder structure. Whereas cheeses with BC had a higher amount of peptides released by chymosin, e.g. the bitter peptide β-casein (f193-209) or by starter proteases from the chymosin-produced peptide α-CN (f1-23). BC cheeses were also judged to be softer by the sensory panel. Cheeses containing the OLb-culture had a higher amount of free amino acids and lower strain at fracture, which correlates to a shorter structure, and the peptide profiles of cheeses produced with BC and CC were rather similar after 28 weeks in contradiction to cheeses with O-culture. Replacing the traditional coagulant BC with CC reduced bitterness but increased hardness of the reduced-fat Cheddar cheese. Replacing O- with OLb-culture also reduced bitterness but resulted in a shorter structure. The results highlight tools which could be employed to alter primary proteolysis and amino acid release, respectively, for the optimisation of flavour and structure of reduced-fat cheese. [ABSTRACT FROM AUTHOR]

A correction to the article "Manufacture and biochemical characteristics during ripening of Cheddar cheese with variable NaCl and equal moisture content," by Fergal P. Rattray and colleagues is presented.

An understanding of coagulation and factors that affect cheese microstructure is important, as this microstructure influences cheese texture and flavour. Of particular importance to many producers is the loss of milk fat during the cheese-making process, which reduces the inherent value of the product. The aim of this study was to investigate the effect of coagulation temperature on the microstructure of gel, curd and cheese samples during the manufacture of full fat Cheddar cheese. The microstructure of the gel formed at 27 °C consisted of a fine interconnected protein network as compared to a coarse, irregular and more discontinuous protein network in gel formed at 36 °C. At a higher coagulation temperature (36 °C), the size of the casein micelle aggregates in the protein strands increased when observed using confocal laser scanning microscopy possibly due to increased hydrophobic and ionic interactions and the rearrangement of casein micelles. This characteristic microstructure observed in the gel was retained in the curd collected prior to whey draining and may be responsible for the increased loss of fat in the whey. The concentration of fat in dry matter in cheese prepared from cheese-milk coagulated at 27 °C and 30 °C was significantly ( P < 0.05) higher than in cheese made from milk coagulated at 33 °C and 36 °C possibly due to the observed differences in microstructure and the direct effect of coagulation temperature on physical properties of the fat and the casein micelles. Our results suggest the need to control milk coagulation temperature, as this parameter may affect product microstructure and fat retention. [ABSTRACT FROM AUTHOR]

lactic acid bacteria Leuconostoc paramesenteroides was isolated and characterized from cheddar cheese and was adapted to grow at low pH (2.0) and high bile salt concentration (2%) by sequential sub-culturing so that it can survive the extreme environmental condition of gut. Cell hydrophobicity assay shows the maximum adherence of the culture to toluene (46.11%). Adhesion ability was confirmed by in vitro assay using rat intestinal epithelial layer. The culture has an antimicrobial activity against food borne pathogens and is vancomycin sensitive. The culture shows a β-galactosidase activity of 3.42 μM/mg protein, which indicates the ability of the culture to hydrolyze lactose for easy absorption. All these properties determine the ability of the culture to be used as a probiotic. [ABSTRACT FROM AUTHOR]

Objective:To investigate the influence of the addition of various toppings/fillings on the glycaemic response to baked potato, pasta and toast.Design:Randomised, repeated measures design.Setting:Oxford, UK.Subjects:Forty normal, healthy subjects (11 males and 29 females) were recruited to the study. Subjects were staff and students from Oxford Brookes University.Intervention:Cheddar cheese, chilli con carne, baked beans and tuna were added to baked potatoes, cooked pasta and toast to determine the effect on glycaemic response.Results:No significant difference was found among the various toppings and baked potato (P=0.06), pasta (P=0.06) and toast (P=0.39). However, the addition of toppings to a carbohydrate-rich food had a consistent lowering effect on glycaemic index (GI). In particular, the addition of cheddar cheese to potato, pasta and toast reduced the GI of the test meal to a value that is considered to be low-GI (39, 27 and 35, respectively). This is particularly notable for potatoes, which, when eaten alone, had the highest GI value of all the staples.Conclusions:This study has shown that the addition of foodstuffs to the staples baked potato, pasta and toast had a consistent lowering effect on the GI value of that meal. These findings emphasise the importance of investigating the GI of composite meals.Sponsorship:British Potato Council.European Journal of Clinical Nutrition (2006) 60, 763–769. doi:10.1038/sj.ejcn.1602380; published online 25 January 2006 [ABSTRACT FROM AUTHOR]

Why it is easier to cut with even the sharpest knife when `pressing down and sliding' than when merely `pressing down alone' is explained. A variety of cases of cutting where the blade and workpiece have different relative motions is analysed and it is shown that the greater the `slice/push ratio' 4 given by (blade speed parallel to the cutting edge/blade speed perpendicular to the cutting edge), the lower the cutting forces. However, friction limits the reductions attainable at the highest 4. The analysis is applied to the geometry of a wheel cutting device (delicatessan slicer) and experiments with a cheddar cheese and a salami using such an instrumented device confirm the general predictions. [ABSTRACT FROM AUTHOR]

Lactococcus lactis subsp. cremoris strains KH (prtlac) and KHA (prtlac) are used as starter cultures in manufacture of ripened cheeses. The growth characteristics and the dipeptidases produced by these cells have been investigated in this study. A new semisynthetic medium was developed for growth of the cells. Growth on this medium was as good as or better than that on milk, the natural medium for cheese starters. Production of proteinases and dipeptidases by these cells was monitored. The effect of temperature on the activity and on the half-lives of dipeptidases was determined. [ABSTRACT FROM AUTHOR]

A mathematical model has been developed for the key reactions taking place during cheese ripening. It includes growth and lysis of cells in the cheese matrix, cell-wall bound proteinases and intracellular peptidases that are released into cheese upon cell lysis, and the production of peptides and amino acids from casein in cheese. The model parameters have been estimated using published experimental data for cheddar cheese, and model simulations have been conducted to suggest effective means of reducing ripening times of cheeses. The time required for ripening of cheeses can be significantly reduced by carefully controlling the cell numbers at the beginning of cheese ripening and their proteinase and peptidase activities. [ABSTRACT FROM AUTHOR]