• Journal of Marine Bioscience and Biotechnology
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• v.2 no.4
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• pp.238-244
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• 2007

Nowadays many people are concerned about being healthy, and many dairy products are taken as health supplementary foods. Among dairy products, kefir, also called as Tibet mushroom, is a yogurt fermented by kefir grain, which is a mixture of lactic acid bacteria and yeasts. Although there are many empirical evidences that kefir is very influential for human body, the exact reason is not definitively discovered. Therefore, it would be useful to understand characteristics of a kefir grain and to categorize bacteria in a kefir grain. In this paper, molecular biological apparatus such as PCR, electrophoresis, PCR purification, DNA sequencing were used to identify and classify the species of lactic acid bacteria and yeast in a kefir grain. We used PCR-based identification method using 16S rRNA primer and Internal Transcribed Spacer (ITS) primer. We identified 6 different species which were selected on different medium. In addition, observation with scanning electron microscope (SEM) enabled us to grasp an external shape of the kefir grain. Although we found a limited number of microbial species, more intensive research are needed for extensive identification of microorganism species in Korean kefir grain.

• Microbiology and Biotechnology Letters
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• v.52 no.2
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• pp.152-162
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• 2024

The microbial starter used to produce kefir beverages, kefir grain, contains a microbial exopolysaccharide called kefiran. Kefir grain consisting of water-insoluble polysaccharides, proteins, and fats, which can be applied as a multi-functional biopolymer. The mass of kefir grain can increase in the fermentation process of Kefir, but it is considered very slow. The purpose of this research is to study the impact of ammonium sulfate supplementation and yeast extract on reconstituted skim milk to increase the mass kefir grain and physical properties of kefiran. Results showed that the ammonium sulfate-supplemented substrate increased the mass of kefir grain by 547% in 14 days, with the condition that the substrate must be renewed every 2 days. Refreshing the substrate is considered one of the important factors. Supplementation on substrate did not appear to affect the viability of bacterial and yeast cells. Kefir grain produced from supplemented substrate also yields better thermal stability properties and has more functional groups than without supplementation. Two Lacticaseibacillus rhamnosus (RAL27 and RAL43) and one Limosilactobacillus fermentum (RAL29) were found to produce EPS. The three isolates also showed good skim milk fermentation ability after purification from kefir grain. The kefir grain produced in this study has the potential for wider application. This study also showed that kefir grain can be adjusted in quantity and quality through fermentation substrate engineering.

• The Korean Journal of Food And Nutrition
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• v.23 no.4
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• pp.462-469
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• 2010

This study was conducted to investigate the physicochemical properties of Kefir. The general composition of Kefir cultured in skim milk or milk was, respectively, 90.0 and 87.8% water, 3.2 and 3.0% protein, 0.45 and 3.64% lipid, 3.96 and 4.14% lactose, and 0.77 and 0.68% ash. Titratable acidity(TA) and pH of Kefir were 0.77 and 4.55, respectively. The amount of $CO_2$ production was 6.23%, and the concentration of alcohol was 1.4%. Kefir grain as observed by scanning electron microscope was a complex mixture of lactic acid bacteria and yeast in a symbiotic association.

• Journal of Dairy Science and Biotechnology
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• v.31 no.2
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• pp.99-108
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• 2013

Kefir is a unique fermented dairy product resulting from combined lactic acid and alcoholic fermentation of lactose in milk. Kefir is produced by the microbial activity of kefir grains. Kefir has numerous health benefits such as the reduction of cholesterol levels, stimulation of the immune system, antimutagenic and anticarcinogenic properties, and improvements of lactose intolerance. Furthermore, kefir is excellent as both a dietetic beverage and for protection against various diseases in small babies. Therefore, kefir has recently been regarded as an important functional dairy food. To date, the majority of research on kefir has focused on the applications of functional kefir using advanced biotechnology methods. The purpose of this review article is to facilitate the recognition of kefir as a novel functional food.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2001.06a
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• pp.77-77
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• 2001

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.5
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• pp.711-715
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• 2005

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$^{\circ}C$ 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$^{\circ}C$ produces the highest MCT levels.

• Food Science of Animal Resources
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• v.27 no.4
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• pp.538-542
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• 2007

This study was carried out to investigate the toxicity of exopolysaccharides (EPS) from kefir toward MA104 cells and evaluate the inhibitory effects of kefir EPS on rotavirus infection. The results obtained are summarized as follows: Lactic acid bacteria (Lactobacillus fermentum, L. acidophilus, L. brevis) and yeasts (Candida kefyr, Cryptococcus albidus, Pichia ohmeri) were isolated and identified from kefir grain and culture. At 1% EPS, the inhibitory effects of EPS on the infection of MA-104 cells using the MTT assay were $72.52{\pm}6.48%$ for human rotavirus (KU), $36.06{\pm}7.63%$ for bovine rotavirus (NCDV), and $81.66{\pm}1.11%$ for porcine rotavirus (OSU). At 1/128% EPS, the effects were $24.98{\pm}4.58%$ for human rotavirus (KU), $4.71{\pm}6.16%$ for bovine rotavirus (NCDV), and $4.05{\pm}14.90%$ forporcine rotavirus (OSU). EPS isolated from kefir have inhibitory effects on rotaviruses of various serotypes and rotaviruses from different animals.

• Food Science of Animal Resources
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• v.31 no.1
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• pp.81-85
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• 2011

The inhibitory effect of a polysaccharide from kefir on human rotavirus infection in MA-104 cells was investigated. The extracted polysaccharide was separated as fraction I in unbound materials and as fractions II, III, and IV in bound materials. Adding polysaccharide fractions II (4.8 mg/mL), III (5.3 mg/mL), and IV (1.4 mg/mL) inhibited the infection of MA-104 cells by human rotavirus. The 50% inhibitory concentrations (IC 50) were 0.075, 0.083, and 0.022 mg/mL, respectively. Based on these results, the kefir polysaccharide has anti-rotavirus activity. In conclusion, a polysaccharide from kefir had more than a 97% inhibition effect against human rotavirus infection in MA-104 cells.

• Journal of Life Science
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• v.26 no.6
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• pp.689-697
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• 2016

Kefir is an acidic-alcoholic fermented milk product originating from the Caucasian mountains. Kefir has long been known for its probiotic health benefits, including its immunomodulatory effects. The objectives of this study were to investigate the properties of a fermented whey product and to examine the effects of kefir grains on the in vitro immune-modulation of human mast cell-1 (HMC-1). The results showed that the whey fermented by kefir grains contained the maximum lactic acid bacteria and yeast for 16 hr by 1.83×10⁸ and 6.5×10⁵ CFU/ml, respectively, and lactose and whey proteins were partially hydrolyzed. The experimental whey fermented by kefir grains exhibited an in vitro anti-inflammatory effect on the HMC-1 line for 8, 16, and 24 hr, and this effect induced the expression of interleukin (IL)-4 as a pro-inflammatory cytokine, but not for 48 hr by RT-PCR in HMC-1 cells. In addition, the same phenomenon was observed for the expression of IL-8 as a pro-inflammatory cytokine by the kefir-fermented whey during the same periods of 8-48 hr under the same conditions. These cytokines resulted in the production of IL-4 at 20-25 ng in HMC-1 cells for 8, 16, and 24 hr, whereas 5 ng was produced for 48 hr by the fermented whey. In contrast, IL-8 was produced at 15-20 ng in HMC-1 cells during 4, 8, 16, and 24 hr, while 7 ng was produced at 48 hr. It was concluded that the whey fermented by kefir grains possesses a potential anti-inflammatory function, which could be used for an industrial application as an ingredient of functional foods and pharmaceutical products.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2002.05a
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• pp.167-167
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• 2002