Optimization of Fermented Tofu with High Isoflavone Content through Variation of Inoculum Percentages and Ratios of Lactobacillus plantarum, Lactobacillus acidophilus, and Leuconostoc mesenteroides

Abstract

Tofu is a traditional food that can be found in several countries, such as Indonesia and Japan. Tofu is often made using the backslopping method, which brings the risk of pathogenic microorganism contamination and can lead to failure in production. Standardization of the production process is necessary in order to yield highly nutritious tofu that is safe to be consumed. In this research, standardization was investigated by variation of the inoculum percentages and ratios of Lactobacillus plantarum (a), Lactobacillus acidophilus (b), and Leuconostoc mesenteroides (c). The inoculum percentages used in this research

Microorganism Selection and Determination of Mixing Ratio of Selected Strains in the “Chao” Production

“…In the previous study, a pure strain of fungi coded NM1 and three pure strains of bacteria coded VK1, VK2 and VK3 were successfully isolated from "chao" production Da Nang [7]. NM1 exhibited white color, thick and long, VK1 exhibited slightly brown, VK2 exhibited gray and VK3 exhibited yellow [6]. The pure strains of microorganisms were well developed at 65%-75% humidity.…”

“…The formol nitrogen content of the product depends on protease hydrolysis activity of microorganism strains [4,6]. So, the following step is the determination protease hydrolysis activity of microorganism strains using for fermented tofu cakes.…”

“…The powder of NM1-VK1 was prepared by taking 0.25, 0.5, 0.75, 1, 1.25 and 1.5 g for each of 100 g tofu cake. The tofu cakes were covered with the powder at 1% portion, then inoculated at 30-32 °C for 6 h [6].…”

“…The product "chao" is of good quality with sensory indicators as follows: color white to yellow, may be light gray; texture solid surface, inside smooth not to be crushed; smell characteristic aroma, no strange smell; taste fragrant, fatty, no bitter taste [4]; content of formol nitrogen is about 0.7%-0.85% [5]. The pure microorganism strains used in production "chao" must meet the following requirements: (1) create enzymes with high protease hydrolysis activity; (2) have no toxic in the product; (3) give the final products with specific characteristics; (4) do not cause unpleasant smell; (5) acquire a thick structure of the fungal hyphae; (6) create a strong film on the surface to retain the original shape after the process of technology [2,6]. The microorganisms must have a high protease hydrolysis activity to produce formol nitrogen.…”