This study aimed at investigating the impact of adding microbial transglutaminase (MTGase) after rennet addition on some properties of fresh soft cheese made from camel milk. MTGase was added to milk at concentration of 80, 100 and 120 U⁄L after 20 and 30 min of renneting. The chemical composition, yield, hardness, antioxidant activity and sensory properties of cheese were estimated. Enzymatic protein crosslinking was analyzed by SDS-PAGE. Results revealed that MTGase-treated cheeses were higher in moisture and lower in protein content compared to control. In addition, the concentration of MTGase and time of addition significantly (P < 0.05) impacted these parameters. Among treated cheeses, samples with 80 U of MTGase and addition time of 20 min were the highest in total solids and protein content. Adding MTGase significantly (P < 0.05) increased the cheese yield, however, increased MTGase concentration at any time of addition did not improve it. The electrophoretic patterns of MTGase-cheese proteins showed a reduction in the intensity of caseins bands and the appearance of new protein fractions with high molecular weights. However, the changes in the intensity of the whey proteins bands were not sufficiently clear as caseins. The cheese hardness was significantly (P < 0.05) affected by adding MTGase. Cheese containing 80 U of MTGase had the highest hardness value compared to control and other treated samples. The antioxidant activity of cheese was negatively influenced by adding the enzyme. The use of MTGase enhanced the mouthfeel, texture and overall acceptability of cheese. However, the effect of MTGase concentration and addition time was not significant (P > 0.05) on the sensory attributes. In conclusion, adding MTGase to milk at concentration of 80 U after 20 min of renneting is recommended to improve the yield, textural and some sensory properties of fresh soft cheese made from camel milk.

This study aimed at improving the antioxidant capacity of fermented camel milk using some single strains of Lactobacillus (Lb. helveticus B-734, Lb. casei subsp. casei B-1922, Lb. paracasei subsp. paracasei B-4560, Lb. rhamnosus B-1445 or Lb. rhamnosus B-442), as well as evaluating the acceptability of the final products. The acidity, proteolysis degree, antioxidant activity, viscosity and organoleptic properties of fermented milk were assessed during 14 days of storage at 4˚C. Total phenolic content (TPC), DPPH radical scavenging activity, Ferrous ion chelating ability (FCA) and Ferric reducing antioxidant power (FRAP) assays were used to determine the antioxidant activity of fermented milks. The results indicated that fermented milks differed significantly (P < 0.05) in all studied parameters due to the type of starter culture used. During storage period, samples containing Lb. helveticus had the highest proteolysis degree, while samples with commercial starter culture (control) showed the lowest degree of proteolysis. Fermented milks containing Lactobacillus strains showed higher DPPH radical scavenging activity compared to those samples containing commercial starter culture. By the end of storage, there was a significant improvement (P < 0.05) in scavenging activity for all fermented milk samples. Regarding FCA, at the beginning of storage fermented milks containing Lb. paracasei, Lb. rhamnosus B-442 or commercial starter culture had the highest FCA values, while Lb. rhamnosus B-1445 samples recorded the highest value at the end of storage. Lb. helveticus samples had the highest TPC and FRAP values (P < 0.05) throughout the storage. There was a high significant correlation (P < 0.0001) between the proteolysis degree and the values of FRAP and TPC. Samples containing Lb.

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This study investigated the effect of using different combinations of commercial starter culture and lactobacilli strains on the antioxidant properties of fermented camel milk for 14 days. The bacterial strains included Lb. casei subsp. casei B-1922, Lb. paracasei subsp. paracasei B-4560, Lb. rhamnosus B-442 and Lb. rhamnosus B-1445.