FOOD SCIENCE ›› 2020, Vol. 41 ›› Issue (14): 161-168.doi: 10.7506/spkx1002-6630-20190515-168

• Bioengineering • Previous Articles     Next Articles

Fermentation of Indica Rice Flour Slurry by Three Pure Strains of Lactobacillus and Characterization of Amylases Produced by Them

LIANG Yan, CHEN Zhong, LIU Bingjie   

  1. (1. Guangdong Institute of Food Inspection, Guangzhou 510080, China; 2. School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, China; 3. Dongguan Shilong Jinwei Beverage Food Co. Ltd., Dongguan 523320, China)
  • Published:2020-07-29

Abstract: In this paper, pure culture fermentation of indica rice flour slurry with three strains of Lactobacillus with the ability to degrade starch, L. acidophilus 14 (La), L. casei M (Lc) and L. plantarum 115 (Lp), was studied. It was found that all the strains had the ability to produce acid in fermented indica rice flour slurry, and the acid-producing ability at 12 h was in the decreasing order La > Lp > Lc. At the same time points, viable bacterial counts also followed this trend. The fastest increase in viable cell number and the strongest acid-producing capacity were observed for La from 4 h to 8 h, and for both Lc and Lp from 6 h to 10 h. The activities of amylases produced by the three strains (named La-a, Lc-a and Lp-a), followed the decreasing order: La-a > Lp-a > Lc-a. The maximum activity of La-a was 79.78 U/mL at 6 h, while the maximum activity of Lc-a and Lp-a was 51.89 and 68.77 U/mL at 8 h of fermentation, respectively. The three amylases were all neutral enzymes. The optimum temperatures of La-a, Lc-a and Lp-a were 55, 45 and 50 ℃, respectively, and the optimum pH values were 6, 7 and 6, respectively. The three amylases could not tolerate temperatures above 70 ℃, but Lp-a was relatively heat tolerant. Their pH stability was La-a > Lp-a > Lc-a. After fermentation, the total starch content in indica rice flour slurry decreased significantly, while the proportion of amylose in the total starch increased, indicating that a certain amount of isoamylase was produced during fermentation.

Key words: Lactobacillus; indica rice flour; amylase; enzymatic characteristics

CLC Number: