A variety of natural vinegar products are found in civilizations around the world. A review of research on these fermented products indicates numerous reports of health benefits derived by consumption of vinegar components. Therapeutic effects of vinegar arising from consuming the inherent bioactive components including acetic acid, gallic acid, catechin, ephicatechin, chlorogenic acid, caffeic acid, p-coumaric acid, and ferulic acid cause antioxidative, antidiabetic, antimicrobial, antitumor, antiobesity, antihypertensive, and cholesterol-lowering responses. The aims of this article are to discuss vinegar history, production, varieties, acetic acid bacteria, and functional properties of vinegars.
Kefir is a unique cultured dairy product due to combined lactic acid and alcoholic fermentation of lactose in milk. Kefir is produced by microbial activity of "kefir grains" which have a relatively stable and specific balance of lactic acid bacteria and yeast. Due to the claimed health benefits of kefir which include reduction of lactose intolerance symptoms, stimulation of the immune system, lowering cholesterol, and antimutagenic and anticarcinogenic properties, kefir has become an important functional dairy food and consequently, research on kefir has increased in the past decade. In the following review, recent studies on the functional properties of kefir are reviewed.
Microbial populations in kefir and kefir grains were enumerated by plating. Total lactic acid bacteria, lactoccocci, lactobacilli and yeast populations increased during fermentation and increased slightly during cold storage. Kefir grains had a lactic acid bacteria : yeast ratio of 10
9
: 10
6
. In further studies, kefir grains were observed using scanning electron microscopy (SEM) methods, which indicated yeast colonization on the surface and middle part of the kefir grain. Three types of lactobacilli (short, long and curved) were noted throughout the grain. Lactococci were not observed under SEM; preparation of kefir grains for SEM may have caused removal of lactococci from the grains.
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