Physiological Characteristics of Starter Isolated from Kimchi and Fermentation of Tofu with Isolated Starter
2012
Kang, K.M., Catholic University of Daegu, Gyungsan, Republic of Korea | Lee, S.H., Catholic University of Daegu, Gyungsan, Republic of Korea
Sixty strains of lactic acid bacteria were isolated from kimchi and used as a starter for fermented tofu. Among the isolated strains, strain KL-6 showed antimicrobial activity against various pathogens, antioxidative activity, and viability in artificial gastric juice and artificial bile acid. The selected strain KL-6 was identified as Pediococcus acidilactici KL-6 by morphological and physiological tests, including Gram staining, catalase test, and 16S rRNA sequencing. The fermentation characteristics of tofu with a kimchi ingredient mixture (Control) consisting of red pepper, garlic, ginger, sugar, salt, jeotgal, and juice of chinese cabbage were compared with those of tofus inoculated with strain KL-6 and the kimchi ingredient mixture (TL) or a pre-fermented kimchi ingredient mixture (TPL) for 24 hr at 37℃. The pH levels of all tested tofu samples decreased after 1 week of fermentation, reaching 3.96 (control), 3.97 (TL), and 4.03 log cfu/g (TPL) after fermentation for 14 weeks at 20℃. Total aerobe content of fermented tofu increased until 2 weeks of fermentation, but decreased steadily thereafter. The number of lactic acid bacteria reached 10∨6 cfu/g after 1 week of fermentation in TL and TPL, whereas it took 2 weeks for the control. The number of lactic acid bacteria in all tested tofu samples reached 10³ cfu/g after 14 weeks of fermentation at 20℃. Coliform bacteria were not detected in TL or TPL after 1 week of fermentation. The sensory scores of TL and TPL were higher than that of control in terms of taste, flavor, texture, and overall acceptability. The sensory quality of TPL was the best among all tested fermented tofu samples.
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