Commercial whey powder, whey protein concentrates and whey protein isolates (WPIs) were evaluated for certain functional properties and for their application in full‐fat and nonfat yoghurts. The functional properties of whey products varied, and the highest functionality was recorded in samples with high protein levels. Whey powder had the lowest foaming performance and emulsifying capacity, while WPIs possessed the best functional properties of all the other samples. Curd tension (CT), viscosity and syneresis were improved in yoghurts made using fortified cow's milk or reconstituted skim milk with any whey products, while whey powder had no impact on CT.

The effect of the water extract of green chilli pepper (WECP) on some properties of low‐fat fresh cheese was studied. Cheese was manufactured from a mixture of reconstituted skim milk powder, whey protein concentrate and sodium chloride and fortified with WECP at concentrations of 0, 1, 2 and 3%. The addition of WECP significantly decreased the total and lactic acid bacteria counts as well as the yeasts and moulds counts in the fortified cheeses. The flavour was improved in cheeses made using 1 and 2% WECP, and the cheese manufactured with 2% WECP had the highest flavour and total scores.

The ability of Levilactobacillus brevis, Lactiplantibacillus plantarum and Pediococcus lolii to grow and produce selenium nanoparticles (SeNPs) in milk permeate or MRS media supplemented with 100 or 200 ppm of inorganic selenium, in the form of sodium selenite (SeIV), was investigated. The permeate medium enhanced the acidity development (reduction of pH) for the three strains; however, MRS medium was more suitable for the lactic acid bacteria strains. Despite these results, the conversion rate of SeIV to SeNPs among all strains was almost similar (99.0-100%) in permeate vs (97.6-100%) in MRS media. Milk permeate medium produced smaller SeNPs particles compared to MRS medium.

T HE effect of pH (7,5 and 3), and the addition of glucose, sucrose and Litesse II, as well as sodium chloride (1,2 and 3%) on the functional properties of whey protein isolate and whey protein concentrate was investigated. Foaming capacity and emulsifying activity index were significantly affected by the change of the pH in the prepared solutions. The addition of glucose to protein solutions had a slight impact (P>0.05) on the functional properties, while the foaming capacity of whey protein isolate solution significantly increased with the presence of sucrose. Litesse II significantly increased the foaming capacity of whey protein isolate and whey protein concentrate solutions, whereas the emulsifying activity index of whey protein isolate solution significantly increased with adding 1 and 2 % Litesse II. The addition of NaCl significantly increased the foaming properties of whey protein isolate and whey protein concentrate solutions and increased the emulsifying activity index of whey protein concentrate solution.

The effect of some growth conditions on the production of exopolysaccharide (EPS) by Pediococcus acidilactici was studied. Furthermore, the impact of utilisation of the isolated EPS, dextran and P. acidilactici on some properties of Kariesh cheese was investigated. The maximum EPS production by P. acidilactici was obtained after 10 h of incubation at 37°C in MRS medium with an initial pH of 7. Kariesh cheese manufactured with dextran or P. acidilactici exhibited the highest (P ≤ 0.05) moisture content and the lowest hardness values. Protein, fat, ash, total bacterial and yeast and mould counts were not significantly affected by the applied treatments. However, the body and texture of Kariesh cheese were significantly improved.

T HIS RESEARCH aimed to study the effect of hydrolysis of whey protein concentrates (WPCs) using trypsin enzyme on their functional properties and use of the modified concentrates in the manufacture of yogurt. Two types of whey were used, sweet whey from Ras cheese and salted whey from Domiati cheese manufacture. Whey protein concentrates were prepared by ultrafiltration of the sweet whey (UFWPC), and precipitation of the salted whey (SWPC) at 90°C / 20 min and pH 4.6. The prepared whey protein concentrates were treated with trypsin enzyme at concentrations of 0.15, 0.3 and 0.5 g enzyme per 100 g protein, and freeze dried. The results showed that the hydrolysis of whey protein concentrates had insignificant effect on the moisture, fat, ash and lactose, while the total nitrogen content and the degree of degradation significantly increased by increasing the concentration of the enzyme. Water and fat absorption capacities were increased by increasing the enzyme concentration and were higher in UFWPC. Emulsification capacity, foaming properties and the ability to form gel were improved by increasing the concentration of the enzyme. The replacement of skim milk powder with hydrolyzed WPCs (by 0.5 g trypsin /100 g protein) in the manufacture of yogurt increased TS, TN and ash content and decreased the pH. Curd syneresis significantly decreased in all treatments compared to control, however treatments with UFWPC exhibited the lowest values. The substitution of 50% and 75 % skim milk powder (SMP) with SWPC and UFWPC in order, had no effect on sensory properties of the yogurt compared to control.

Background Fresh milk and natural environmental conditions are used to produce traditional cheeses. Such cheeses are produced by dozens of different types of microbes. Non-starter lactobacilli are the most responsible genus of lactic acid bacteria exhibiting key technological and health promoting traits. The purpose of this study is to isolate Lactobacillus bacteria from conventional Egyptian cheeses and analyse their probiotic potential and technological properties. Results Lactobacillus isolates (33 isolates) were isolated from different Egyptian cheeses. Our results revealed that 18.18% of the isolates were fast-acidifying, 30.3% were medium-acidifying and 51.5% were slow-acidifying isolates. The results of autolytic activity showed that 24.3% of the isolates were good autolysis, 33.3% were fair autolysis, while 42.4% were poor autolysis. Fifteen isolates produced exopolysaccharides, while 9 isolates exhibited antimicrobial activities against Lactobacillus bulgaricus 340. All the isolates were resistant to pH 3 for 3 h except isolate No. 15 (MR4). The growth rate of the isolates ranged from 42.25 to 85.25% at 0.3% bile salts after 3 h of incubation. The surviving percentage of the Lactobacillus isolates decreased with increasing incubation time or the percentage of bile salts greater than 0.3%. All the isolates grew after incubation in artificial gastric and intestinal fluids. The auto-aggregation of 15 isolates ranged from 43.13 to 72.77%. Lacticaseibacillus paracasei BD3, Lactiplantibacillus plantarum BR4 and Limosilactobacillus fermentum MR2 were sensitive to the majority of the tested antibiotics and showed good bile salt hydrolase activity. Conclusion L. paracasei BD3, L. plantarum BR4 and L. fermentum MR2 were isolated from Egyptian cheeses and showed probiotic and technological characterization, which are valuable for their practical application as starters, adjunct and protective cultures in cheese making.