Microbial contamination of tofu in Korea and growth characteristics of Bacillus cereus isolates in Tofu

Spoilage Bacteria Identification and Food Safety Risk Assessment of Whole Soybean Curd

“…Common filled soybean curd was soaked with water or whey, thus the internal environment of soybean curd was anaerobic and the growth of aerobic bacteria was inhibited. Lee et al (2017) analyzed the population distribution of aerobic bacteria in 100 commercial tofu in Korea, and only 32% of the samples showed positive detection results of aerobic bacteria. Moreover, 59.4% of the positive samples exhibited a contamination level below 3 log CFU/g, which was in consistent with our results.…”

“…Inaquosorum and Bacillus cereus, respectively. B. cereus is a gram-positive, endosporeforming and facultative anaerobic pathogen, which has been detected in cooked beans and soybean curd (Juneja et al 2018;Lee et al 2017). If the environmental conditions were suitable, the spores of B. cereus would germinate.…”

“…The serially diluted mixture was poured into melted trypticase soy agar (TSA) medium. After incubation at 37°C for 48 h, colonies different in morphology on TSA medium were separated and purified for species identification (Lee et al 2017).…”

“…To describe the influence of temperature on the lag time and maximum growth rate, exponential decay equation (Eq. 2, Lee et al 2017) and square root equation (Eq. 3, Zhou et al 2009) were selected as the secondary model.…”

“…2. It was worth noting that the shelf life of soybean curd ended when the microbial population reached to 6 log CFU/g (Lee et al 2017). Univariate solution indicated that the shelf life of WSC that were incubated at 10°C and 35°C were 141.95 h (5.91 d) and 3.28 h, of OFC were 206.25 h (at 10°C) and 5.37 h (at 35°C).…”