Microbiological Survey of Tofu Sold in a Rural Illinois County

Abstract

The purpose of this study was to determine the microbial status of tofu sold in a rural Illinois county and assess the factors contributing to the safety of tofu. Six brands of tofu from eight different stores (60 total samples) were purchased and analyzed for temperature, pH, total aerobic bacteria, and the presence of coliforms. Relationships between age, temperature, pH of tofu, and total aerobic bacteria were tested. An analysis of variance was also performed to test for differences in total bacterial counts among the brands. Mean aerobic bacterial counts ranged from 0 to 7.76 x 10(7) CFU/g. Fifty-five percent of the tofu tested fell within the excellent range for freshness as delineated by the standards developed by the Soyfoods Association of North America, 6.7% fell within the acceptable range, 6.7% within the marginal range, and 28% within the unacceptable range. Sixteen percent of the samples contained coliform bacteria. No significant correlation was found between variables, except pH with total aerobic bacterial counts (r = -0.51) and pH with eosin-methylene blue agar counts (r = -0.67). Most of the tofu was displayed at unsafe temperatures (>5 degrees C) for potentially hazardous foods. This study confirmed the concerns regarding safety of tofu sold in the grocery stores. Based on these results, special training on tofu storage and handling is recommended for grocery stores selling this food product.

Bacterial Contamination of Soybean Curd (Tofu) Sold in Thailand

“…After incubation, strains were isolated by visual observation hands can directly touch it. Tofu is easily spoiled in warm environments by microbial growth due to its characteristics: high protein, high water content, and neutral pH (Asharaf et al, 1999;Tuitemwong and Fung, 1991;van Kooij and de Boer, 1985). Thus, its shelf life is short and storage / distribution is limited.…”

Identification and Review of Sensitivity Analysis Methods

“…ANOVA finds broad application across various fields, including health risk assessment (e.g., Pet‐Armacost et al ., 1999; Gerken et al ., 2000), material testing (e.g., Golinkin et al ., 1997), food quality (Carlucci et al ., 1999; Ashraf et al ., 1999), microbiology (e.g., McElroy et al ., 2000), and microbial risk assessment (e.g., Marks et al ., 1998).…”

Tailed Pepper (Piper cubeba) L. berries extract reduced number of microbial population in tofu

“…Tofu contains approximately 6.0%-8.4% protein and 79%-87% water and has an almost neutral pH (5.2-6.2). The particularly high protein and moisture content of tofu make it a very good medium for microorganisms (Ashraf et al, 1999). Microorganisms have been reported to easily contaminate tofu even when the tofu is refrigerated.…”