BackgroundChanges in colostrum composition of Egyptian buffaloes and Holstein cows collected at calving, 6, 12, 24, 48, 72, 96, 120 h and after 14 days of parturition were studied. Total solids, total protein, whey proteins, fat, lactose and ash contents were determined. Macro- and micro-elements, IgG, IgM, IGF-1, lactoferrin and vitamins (A and E) were also estimated.ResultsAt calving, the total protein and whey proteins concentration did not differ between buffalo and cow colostrum, while total solids, fat, lactose and ash concentrations were higher in buffalo than in cow colostrum. All components decreased gradually as the transition period advanced except lactose which conversely increased. On the fifth day post-partum, concentration of total protein, whey proteins, fat, ash and total solids decreased by 69.39, 91.53, 36.91, 45.58 and 43.85% for buffalo and by 75.99, 94.12, 53.36, 33.59 and 52.26% for cow colostrum. However, lactose concentration increased by 42.45% for buffalo and 57.39% for cow colostrum. The macro-and micro-elements concentration of both colostrums tended to decline slightly toward normality on the fifth day of parturition. Buffalo colostrum had a higher concentration of vitamin E than cow colostrum during the experimental period. At calving, the concentration of vitamin A in buffalo colostrum was found to be approximately 1.50 times lower than in cow colostrum. The concentrations of IgG, IgM, IGF-1 and lactoferrin decreased by 97.90, 97.50, 96.25 and 96.70% for buffalo and 76.96, 74.92, 76.00 and 77.44% for cow colostrum, respectively after five days of parturition.ConclusionsThere is a dramatic change in buffalo and cow colostrum composition from the first milking until the fifth day of parturition. There are differences between buffalo and cow colostrum composition during the five days after calving. The composition of both colostrums approaches to those of normal milk within five days after parturition.

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In this study, milk was hydrolyzed using protease (Asperigillus oryzae), trypsin, pepsin, or papain at concentrations of 0.001, 0.005, or 0.01 g/100 g milk for 30 or 60 min to produce angiotensin-converting enzyme inhibitory and antioxidant peptides. Results showed that the proteolysis, antioxidant, and ACE-I activity gradually increased with the increase in the enzyme concentration and hydrolysis time. The protease-treated milk had the highest proteolytic and ACE-I activity, while the papain-treated milk had the lowest. The papain-treated milk exhibited the greatest Fe 2+ chelating activity. The use of trypsin at concentration of 0.001 g/100 g milk for 60 min produced ACE-I and antioxidant activity without changes in the technological properties of milk.

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In this study, skim milk was fermented using 14 strains for 16 h at 42 °C or for 48 h at 25 °C. On conclusion of fermentation, the proteolytic, angiotensin converting enzyme-inhibitory (ACE-I), and antioxidant activities as well as the inhibition of thrombin and cholesterol micellar solubility were determined. The results revealed that B-4564 exhibited the highest ACE-I activity (68.11%) under the 42 °C for 16 h condition, while B-1445 demonstrated the highest ACE-I activity (92.23%) under the 25 °C for 48 h condition. B-4564 exhibited the highest inhibition rate of thrombin (42.43 and 48.10%) and cholesterol (68.60 and 87.01%) under the 42 °C for 16 h and 25 °C for 48 h conditions, receptively. B-442 exhibited the highest DPPH radical scavenging activity of 95.63 and 62.89% under the 42 °C for 16 h and 25 °C for 48 h conditions, receptively. B-1445 demonstrated the highest Fe chelating activity and reducing power under both the tested fermentation conditions.

In this study, skim milk fermented with 14 commercial dairy starters were evaluated for their proteolysis ability, angiotensin I-converting enzyme (ACE)-I, and antioxidant properties. The antioxidant activity was determined using DPPH radical scavenging, chelating of Fe ions, and reducing power assays. The results showed that the coagulation time, pH, and titratable acidity varied among the used starters and appeared to be starter dependent. Lh-B02 starter had the highest proteolytic and ACE-I activity.-01, Yo-Fast 1, YC-281, MYE 96, and YO-MIX 205 starters had the highest DPPH radical scavenging activity. Chelating of Fe ions of the -01 starter was the highest, whereas the O-114 starter was the greatest in reducing power. Regarding the yogurt starters, Yo-Fast 1 starter exhibited h igh values o f proteolytic, ACE-I, and DPPH radical scavenging activity. A positive correlation was observed between the proteolytic and ACE-I or antioxidant activities of all starters.

Caseins determine the physicochemical, physiological, and biological characteristics of milk. Four caseins—alpha-S-1, alpha-S-2, beta, and kappa—were analyzed phylogenetically and in silico and characterized regarding chemical, antimicrobial, and antioxidant features in five dairy animals: Arabian camels, sheep, goats, cattle, and water buffalos. The sequence of full-length amino acids of the four caseins for the five species was retracted from the NCBI GenBank database. Multiple sequence alignment is used to examine further the candidate sequences for phylogenetic analysis using Clustal X and NJ-Plot tools. The results revealed that sheep and goats possess strong similarities (98.06%) because of their common ancestor. The same was observed with cattle and water buffalos (96.25%). The Arabian camel was located in a single subclade due to low similarity in casein residues and compositions with other dairy animals. Protein modeling showed that alpha-S1- and alpha-S2-caseins possess the highest number of phosphoserine residues. The in silico computed chemical properties showed that β-casein recorded highest hydrophobicity index and lowest basic amino acid content, while α-S2-casein showed the opposite. The computed biological parameters revealed that α-S2-casein presented the highest bactericidal stretches. Only Arabian camel β-casein and k-casein showed one bactericidal stretches. The analysis also revealed that β-casein, particularly in Arabian camels, possesses the highest antioxidant activity index. These results support the importance of the bioinformatics resources to determine milk casein micelles' chemical and biological activities.