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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.

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K. marxianus var. lactis was grown in different whey media (sweet, acid and salted (5%) whey) and permeate and tested for optimum incubation period (24-120 hr) for biomass production. The effect of adding either yoghurt starter or L.helviticus (at 2% rate) was also investigated. The optimum pH (3,4,5,6&7), type of supplement to enhance biomass production and the ability of the growth in salted why (0, 3, 5, 7, & 9%) in the presence of lactic acid bacteria was also studied.The best biomass production by K.marxianus var. lactis was in sweet whey at incubation period of 96 hr in the presence of L.helviticus (2%) and yeast extract (0.2%) at pH 4 to 5. It also caused a high reduction in lactose content and BOD of whey. The biomass production decreased as the salt concentration increased, but in the presence of L.helviticus salt tolerance increased and biomass production increased by 14-35% in the presence of up to 9% salt. * Initial lactose = 4.9 %. * Initial BOD = 73000 mg/l. * Growth conditions: 96 hr, at pH 4-5. * Different superscripts at the same column are significantly different (p<0.05).

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