Lactic acid bacteria are generally defined as a cluster of lactic acid-producing, low %G+C, non-spore-forming, Gram positive rods and cocci that share many biochemical, physiological, and genetic properties. According to current taxonomy, this group of bacteria consist of twelve genera, however only few genera are involved in food, such as Lactococcus, Streptococcus, Leuconostoc, Lactobacillus, and Pediococcus. Lactic acid bacteria have been involved in foods from three different ways, these are: as a starter culture for producing fermented foods, as a component for probiotic-foods, and as bio-preservatives. Of course, mixture between these three ways is also possible, such as using probiotic strains as well as bacteriocin producers which potential for bio-preservatives for starter cultures. These have been a major of research area for exploitation of lactic acid bacteria in Indonesia, particularly at Gadjah Mada University.
Lactic acid bacteria have involved in traditional fermented foods. Their capabilities in lowering pH due to the lactic acid produced could give a beneficial effect to the fermented product. Low pH will give more stable product and metabolites which are produced during fermentation, will improve flavor, aroma and texture of the product. Indonesia has many kinds of fermented foods from plant and animal material which are mostly produced by natural/traditional processes. Lactic acid bacteria, which are involved in this fermentation usually, occur naturally in the raw material used for fermentation. However, in order to increase the stability and safety of products, bacteriocin-producers have been used as starter cultures for controlling the traditional fermented foods, particularly based on fish. Bacteriocin producers Pediococcus acidophilus F-11 was able to reduce coliform and histamine producers during fermentation of salted fish (peda) and other fermented fish. Lactic acid bacteria naturally occur in the fermented foods (meat and fish) have been investigated for their role in health, their fermented products was analyzed as anti hypertension. Production of carnosine by lactic acid bacteria occurring in meat fermentation (petis) and also the ACE inhibitor of lactic acid bacteria from fermented fish (bekasam) have been extensively studied.
Selection of probiotic candidates have also been carried out based on the standard criteria, such as resistance to gastric acidity and bile acid, antimicrobial activity against potentially pathogenic bacteria. Several isolates obtained were further studied on their capability in binding aflatoxin occur in buffer and food system. In order to produce of biomass of probiotics with the high stability and viability, micro-encapsulation using several materials has been conducted. These research activities will be discusses further.
Keywords : lactic acid bacteria, starter culture, bacteriocins, and probiotics
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