This study aims to evaluate the antioxidative activities of cow-milk kefir and goat-milk kefir. Antioxidative mechanisms, including radical-scavenging effects, ferrous-ion chelating ability, reducing power and antioxidant activity, were investigated herein. Kefirs demonstrated significantly greater scavenging effects upon 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide radicals, an inhibition effect upon linoleic-acid peroxidation, and more substantial reducing power, but reduced glutathione peroxidase (GSH-Px) activity than was the case for milks. There was no significant difference between milks and kefirs as regards ferrous-ion chelating ability and superoxide dismutase (SOD) activity. These findings have demonstrated that kefirs possess antioxidant activity, thereby suggesting that kefirs are potential candidates for the role of useful natural antioxidant supplements for the human diet.

The purpose of this research was to study the effects of kefir whey (kefir whey, peptides, lactic acid) on skin care properties including skin lightening effect and acne treatment. The final aim was to develop a new cosmetic product and enhance the value of dairy products. The results of skin lightening tests showed that all three kefir whey components (kefir whey, peptides and lactic acid) had inhibitory ability against melanin synthesis. Furthermore, copper chelating analysis demonstrated that both kefir whey and kefir whey peptides could chelate the copper in tyrosinase, which might explain the mechanism of inhibition. The ability for acne treatment indicated that lactic acid level higher than 60 mg/ml could inhibit the growth of Propionibacterium acne, whereas no inhibition was found with other components.

The purpose of this research was to study the effect of freeze drying on the microorganisms in kefir. Influences of lyoprotectants and rehydrated media (water at 4°C, 25°C; 10% reconstituted milk at 4°C, 25°C) on the viability of lactic acid bacteria and yeasts in freeze-dried kefir were investigated. Kefir was made from cow milk which was inoculated with 5% kefir grains, and incubated at 20°C for 20 h. Lyoprotectants (galactose, lactose, maltose, sucrose and trehalose) were added independently before dehydration of kefir by freeze drying. Results indicated significant loss in viability of microorganisms in kefir after freeze-drying. Addition of 10% galactose or 10% sucrose as lyoprotectants significantly increased the survival rates of both lactic acid bacteria and yeasts (p<0.05). The 4°C rehydration temperature showed the best viabilities for yeasts, however, viability was not significantly affected by rehydration media (p>0.05).

One of the prerequisites for the successful implementation of industrial-scale goat kefir production is to understand the effects of different kefir grains and culture conditions on the microbial and chemical properties of the goat kefir. Thus, the objectives of the present study were to evaluate the characteristics of kefir grains in Taiwan on the microbial and chemical properties of goat milk kefir, as well as to understand the influence of culture conditions on production of medium chain-length triglycerides (MCT). Kefir grains were collected from households in northern Taiwan. Heat-treated goat milk was inoculated with 3-5% (V/W) kefir grains incubated at 15, 17.5, 20 or 22.5°C for 20 h, and the microflora count, ethanol content, and caproic (C6), caprylic (C8), and capric acid (C10) levels measured at 4 h intervals. Our results indicate that incubation with kefir grains results in 10 6 -10 7 CFU/ml microflora count and 1.18 g/L of ethanol content at 20 h of fermentation. Incubation with 5% kefir grain at 20-22.5°C produces the highest MCT levels.

The objective of this research was to combine the physiological functionality of probiotics (Lactobacillus acidophilus and Bifidobacterium longum) and the milk-clotting activity of culture filtrate from lao-chao to develop a new dairy product which was different from the commercial yogurt. Rhizopus javanicus and Saccharomyces cerevisiae were chosen as a mold and yeast starter for production of culture filtrate. The study results indicated that both probiotic counts increased with incubation time and maintained 10 7 -10 8 CFU/ml after 6 h incubation with 10-30% culture filtrates. By contrast, samples with 40% culture filtrates inhibited the growth of L. acidophilus and B. longum. The more culture filtrates were added, the lower titratable acidities and higher pH values in Kou Woan Lao were detected after 36 h fermentation. No significant differences (p>0.05) were found for both L. acidophilus and B. longum, when grown in differing concentrations of skim milk powders. Storage results showed both L. acidophilus and B. longum exhibited excellent stability for 14 days at 4°C in the Kou Woan Lao.