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A2 milk, characterised by the presence of only the A2 β-casein genotype, has recently been of great interest due to its potential health benefits, which are the subject of intensive scientific research. From the dairy industry standpoint, it is crucial to ascertain its functional and technological attributes. The objective of this study was to compare two types of yoghurt (A1 and A2 yoghurts), produced respectively from cows' milk containing exclusively β-casein (β-CN) A1 (A1/A1) or A2 (A2/A2) genotypes, in terms of basic chemical composition, protein profile, amino acid composition, antioxidant capacity, sensory quality, acidity, instrumental texture and colour profiles, as well as rheological characteristics. The obtained results indicate that the β-CN polymorphism had no significant impact on the basic chemical composition, acidity, DPPH radical scavenging activity, ferric reducing antioxidant power (FRAP) or colour properties of the yoghurts. Nonetheless, the β-CN genotype did affect the textural, rheological, and sensory qualities of the acidic gels, with A2 yoghurt yielding gels exhibiting higher hardness, gumminess, improved consistency and viscosity, and overall sensory quality compared to the corresponding A1 treatment. These results indicate that A2 milk serves as a good raw material for fermented milk production, warranting further investigation. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of the addition of wild garlic leaves on the sensory quality, volatiles, color, and texture of sheep milk soft rennet-curd cheese. The sensory evaluation of color, appearance, texture, odor, and taste was performed using a 5-point scale. The intensity of selected taste and odor discriminants was also assessed. Volatiles were analyzed by the GC-MS method. Color and textural characteristics were determined instrumentally. The wild garlic addition had no effect on the sensory characteristics of the cheese (p > 0.05). However, cheese with herbs exhibited a less intensive sour odor (p ≤ 0.05), sheep's milk odor, and taste (p ≤ 0.01). (E)-7-methyl-4-decene, dichloroacetic acid undecyl ester, and 3,5-dimethyl-octane, described as creamy, acetic, and acid pungent in smell, were not detected in the cheese with wild garlic while they were present in the natural one. Moreover, herbal cheese was more piquant (p ≤ 0.01). PCA showed that the differences in volatiles resulted both from the use of wild garlic and the time of storage. Herbal addition affected almost all color characteristics, except for the hue angle (h), but caused an increase only in hardness and chewiness. In conclusion, wild garlic leaves can be recommended as an additive in the production of soft sheep's milk rennet-curd cheese. [ABSTRACT FROM AUTHOR]

Background. Recently, interest in the development of functional foods enriched with bioactive components has increased. Dairy products supplemented with tea extracts known for their health-promoting properties are good examples of such products. However, most of the scientific studies and applications focus on green tea. The present study was established to estimate the effect of Pu-erh tea supplementation on the viability of starter microorganisms and selected physico-chemical and sensory properties of probiotic ABT-yoghurt. Material and methods. ABT-yoghurts (Lactobacillus acidophilus La-5, Bifidobacterium animalis ssp. lactis BB-12, Streptococcus thermophilus) were produced from cow's milk with 0%, 5%, 10% or 15% (v/v) of Pu-erh tea infusion added before the fermentation stage. The products obtained were subjected to the following analyses one day after production (colour profile) and after 7, 14 and 21 days of cold storage: ferric reducing antioxidant power (FRAP) and anti-radical power (ARP) measured against DPPH radical, titratable acidity, pH, texture parameters (back extrusion test), viability of starter cultures and sensory quality (hedonic scale experiment). Results. Pu-erh tea supplementation significantly enhanced the antioxidant potential of probiotic yoghurts as a 3-6.5-fold increase in FRAP and a 10-24-fold increase in ARP values were observed in comparison to plain ABT-yoghurt. Pu-erh tea slightly enhanced the viability of L. acidophilus and reduced the pH of probiotic yoghurts. Higher concentrations of Pu-erh tea caused decreased firmness and consistency while cohesiveness and index of viscosity remained unaffected upon supplementation. The addition of Pu-erh tea infusion modified the colour and sensory properties of the probiotic yoghurts but the sensory quality of the tea yoghurts was rated lower when compared to the plain one. Among all tea yoghurts, the one with 15% Pu-erh tea additive received the highest scores in sensory assessment. Conclusion. Pu-erh tea may be successfully applied as a functional additive to probiotic yoghurts, significantly enhancing the antioxidant properties of fermented milk and ensuring a high rate of starter bacteria viability during storage. However, the level of fortification must be carefully chosen as some doses negatively influence texture parameters and sensory quality. [ABSTRACT FROM AUTHOR]

Background. When designing new probiotic products, one of the most important aspects is the selection of bacterial strains with high survival rates in the matrix of the product concerned. The aim of the present research was to evaluate the potential of selected strains of probiotic bacteria for the production of fruit-whey beverages. Materials and methods. Orange, apple and blackcurrant whey beverages were produced, and each was inoculated with one of the following probiotic strains: Bifidobacterium lactis HN019™; Lactobacillus acidophilus NCFM®; Lactobacillus paracasei Lpc-37™; Lactobacillus rhamnosus HN001™. The count of probiotic bacteria as well as pH and total acidity were evaluated at the 1st, 7th, 14th, 21st and 28th day of storage. Results. Beverages containing L. paracasei Lpc-37™ or L. rhamnosus HN001™ were characterized by a significantly higher average number of viable cells (7.02 or 7.05 log cfu/g, respectively) than products with B. lactis HN019™ or L. acidophilus NCFM® (6.43 or 6.37 log cfu/g, respectively). The use of L. paracasei Lpc-37 and L. rhamnosus HN001 strains in orange and apple drinks allows the recommended count for probiotic products, 106 cfu/g for 28 days of storage, to be exceeded. Survival of the B. lactis HN019 strain fulfills the above requirements only in the orange drink. The L. acidophilus NCFM® strain was found to be the least suitable for the production of beverages, as it did not reach 6 log cfu/g in any products after 28 days of storage. The highest average number of bacteria was found in the orange beverages (7.14 log cfu/g). In terms of bacteria viability, blackcurrant juice was the least suitable for the production of whey probiotic drinks, due to its high acidity. Conclusion. The results of the present study indicate that careful selection of the fruit juice component, especially in terms of its acidity, is key to designing successful probiotic fruit-whey beverages. Other factors which should be taken into account to ensure a sufficient number of live probiotic cells, i.e. their therapeutic level in fruit-whey drinks, are the choice of probiotic strain and determination of the maximal shelf life. [ABSTRACT FROM AUTHOR]

BACKGROUND Transglutaminase ( TGase) modifies milk proteins by cross-linking of caseins, with increased cheese yield being the main technological benefit. In the present work the influence of TGase addition in different concentrations (0, 1, 2 and 3 U g−1 protein in the system) and under different incubation conditions (0 h, 40 °C/2 h, 25 °C/4 h and 5 °C/16 h) on the rennet coagulation time ( RCT) and the comprehensive rennet gel properties were investigated. RESULTS Modification of milk proteins by TGase in a concentration-dependent manner caused longer RCT and lower gel firmness. The highest TGase concentration and incubation at 40 °C for 2 h resulted in the longest RCT and the lowest gel firmness. Rennet gels obtained from TGase modified milk were characterised by significantly lower values of texture parameters, lower syneresis and were composed of smaller casein micelles, thinner chains and smaller clusters than those obtained from the control milk. The content of whey proteins in the gel from modified milk was higher and the content of individual casein fractions in the milk samples and rennet gels decreased upon TGase modification. CONCLUSION Rennet cheese with modified textural and nutritional properties and improved yield can be obtained upon TGase modification but simultaneous addition of rennet and TGase is recommended. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Background. Free radicals are connected with the increased risk of certain diseases, especially cancers. There is some scientific evidence that antioxidant-rich diet may inhibit the negative impact of free radicals. The aim of the present study was to analyse the antioxidant capacity of the selected commercial natural and fl avoured fermented milks offered in Poland, derived from different producers. Material and methods. The following commercially available natural fermented milks: 12 yoghurts, 12 kefirs, 2 butter milks, 2 cultured milks, Turkish yoghurt drink (ayran) and the following flavoured fermented milks: 22 yoghurts, 2 acidophillus milks, 2 kefirs, butter milk and vegetable flavoured fermented milk were analysed for their antioxidant potential. The antioxidant capacity was assessed, in two replicates and twice for each product, by means of ferric reducing antioxidant power (FRAP) and DPPH radical scavenging ability (expressed as ARP - anti radical power) methods. Results. Among all analysed plain products, yoghurts and kefirs were characterised by the highest antioxidant activity. The presence of probiotic Lactobacillus casei strains in the product positively affected both FRAP and ARP values. Antioxidant capacity of the fl avoured fermented milks was primarily affected by the type and quality (e.g. fruit concentration) of the added fl avouring preparation. The most valuable regarding the estimated parameters were chocolate, coffee, grapefruit with green tea extract as well as bilberry, forest fruits, strawberry and cherry with blackcurrant fillings. Conclusions. Protein content, inclusion of probiotic microflora as well as type and quality of flavouring preparations are the main factors affecting antioxidant properties of fermented milks. [ABSTRACT FROM AUTHOR]

Background. Vegetables, apart from having high nutritional value, also contain considerable amounts of dietary fibre and other components, which may affect physico-chemical properties of fermented milks, e.g. viscosity, texture, susceptibility to syneresis, flavour profile etc. The present work was established to study the effect of selected vegetables addition on the rheological, textural, microbiological and flavour profile parameters of yoghurts. Material and methods. The vegetable preparations (carrot, pumpkin, broccoli and red sweet pepper) were added (10% w/w) to the processed cow's milk fermented with DVS yoghurt culture. Texture profile analysis, determination of viscosity, susceptibility to syneresis and descriptive flavour evaluation were conducted at the 1st, 7th and 14th day after production. Additionally, microbiological studies were performed for 28 days, at 7-day intervals. Results. The highest apparent viscosity and adhesiveness were obtained for the carrot yoghurt, whereas yoghurt with pumpkin was the least susceptible to syneresis. The other texture parameters were not affected by the addition of vegetables. Broccoli and red sweet pepper flavours were dominating in the fermented milks fortified with these vegetables, whereas carrot and pumpkin flavours were less distinctive. Yoghurt supplemented with red sweet pepper got the highest sensoric acceptability. The number of starter bacteria was not influenced by the vegetable additives, except for pumpkin yoghurt, which contained lower population of lactobacilli. Conclusions. Among all tested vegetables, carrot additive had the greatest potential to improve yoghurt structure, whereas red sweet pepper imparted the most acceptable flavour. [ABSTRACT FROM AUTHOR]

Background. Yoghurt is a fermented milk of unique sensory, nutritive and dietetic value offered in a variety of types and in different flavours. Vegetables belong to the group of food products rich in antioxidant substances (e.g., vitamin C, carotenoids, tocopherols, polyphenols) which regular consumption lowers the risk of many diseases including cancers and cardiovascular disorders. The aim of the present work was to manufacture and assess the acidity, sensory quality and antioxidant capacity of yoghurts with addition of selected vegetables during 2-week refrigerated storage. Material and methods. The vegetable preparations (carrot, pumpkin, broccoli and red sweet pepper) were added to the cow's milk fermented using DVS type yoghurt culture after initial cooling to 15-20°C in the amount of 10% (w/w). The following analyses were performed: determination of pH, titratable acidity, antioxidant activity by ferric reducing antioxidant power (FRAP) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) method as well as sensory evaluation and were conducted after 1, 7 and 14 days of cold storage. Results. The yoghurt supplementation with selected vegetables had no significant effect on the pH and titratable acidity level. The highest ability to scavenge DPPH radicals was stated for yoghurts with broccoli and red sweet pepper. The latter treatment gained the highest notes in sensory evaluation. All vegetable yoghurts were characterised by higher than the natural yoghurt FRAP values measured directly after production. However, the level of this parameter significantly decreased after storage. Conclusions. The red sweet pepper additive was the most beneficial regarding antioxidant properties and organoleptic acceptance of the studied yoghurts. [ABSTRACT FROM AUTHOR]

Background. Magnesium is a micronutrient which plays an important role in a wide range of fundamental cellular reactions. Deficiency of magnesium leads to serious biochemical and symptomatic changes. The present study was carried out to establish the influence of magnesium lactate fortification on the physicochemical, microbiological and rheological properties of fat-free yogurt manufactured using different starters. Material and methods. In this study, yogurts were produced from fat-free milk, standardized with skimmed milk powder to 6% protein content, and then divided into two parts. One part was left without supplementation as a control and in the second part, magnesium L-lactate hydrate was added in the amount of 317.30 mg 100 g-1, which was equal to 35 mg of Mg2+ 100 g-1 of milk. Both mixtures were blended, pasteurized at 85°C for 30 minutes, cooled to 45°C and then divided into three parts, inoculated with: (1) YC-X11 yogurt culture, (2) YF-L811 yogurt culture and (3) VITAL yogurt culture supplemented with probiotics (Lactobacillus acidophilus, Bifidobacterium lactis) respectively. Fermentation was performed at 43°C and the final yogurts were cooled to 5°C. After 24 hours of cold storage, the pH values, titratable acidity, syneresis, color, texture profile, viscosity, sensory analysis and microbiology of the yogurts were analyzed. Results. The results showed that addition of magnesium lactate significantly reduced syneresis and increased the hardness of fat-free yogurts. There was no impact on the viability of starter bacteria in the yogurts after 24 hours of refrigerated storage. Conclusions. Magnesium lactate showed good potential for the fortification of dairy foods, according to physicochemical data. Further research is needed regarding the influence of storage time and to establish whether the observed effects are largely due to the magnesium cation or lactate anion. [ABSTRACT FROM AUTHOR]