유산균주의 종류에 따른 쌀 첨가 요구르트의 발효 특성

Abstract

The objective of this experiment was to select the best strain of lactic acid bacteria for the manufacture of new type of yogurt with rice powders. Changes in pH, titratable acidity, viable cell counts, viscosity, organic acid contents, carbohydrates during fermentation were monitored and sensory evaluation were examined. The yogurt added with 4% rice or skim milk powders and L. salivarius ssp. salivarius culture did not reach pH 4.5, because the production of acids in this media for the culture was weak. The yogurt added with 4% rice or skim milk powder with L. casei, the pH was low and the titratable acidity was high, and therefore the quality of yogurt after 8 hours from fermentation was not high. The yogurt added with 4% rice or skim milk powders with a mixed culture of B. longum, L. acidophilus, Streptococcus salivarius ssp. thermophilus was considered best for achieving pH 4.5 and titratable acidity of 1.0 % from 8 to 14 hours. The yogurt with a mixed culture had more acetic acid. Galactose was accumulated when L. salivarius ssp. salivarius or the mixed culture were used for fermenting yogurt. In sensory evaluation, the yogurt with the mixed culture received high overall sensory score. From these results, a mixed culture of B. longum, L. acidophilus, Streptococcus salivarius ssp. thermophilus was identified as the best for the manufacture of yogurt added with rice powder.