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Control of foodborne pathogens during sufu fermentation and aging
1Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506-1600, USA.
Critical Reviews in Biotechnology
|February 24, 2001
Summary
Sufu fermentation and aging effectively eliminate foodborne pathogens like E. coli and Salmonella. This traditional Chinese cheese is safe for consumption without pasteurization due to these natural control mechanisms.
Area of Science:
- Food Microbiology
- Fermentation Science
- Food Safety
Background:
- Sufu, a traditional fermented soybean product, is popular in East Asia.
- Concerns exist regarding the safety of unpasteurized fermented foods due to potential foodborne pathogens.
Purpose of the Study:
- To evaluate the control of key foodborne pathogens during sufu fermentation and aging.
- To assess the microbial profile of sufu during different aging periods and compare it with commercial products.
Main Methods:
- Inoculation of tofu with four foodborne pathogens (E. coli O157:H7, S. typhimurium, S. aureus, L. monocytogenes) and starter culture (A. elegans).
- Fermentation at 30°C for 2 days, followed by aging in a 10% alcohol + 12% NaCl solution for up to 3 months.
- Microbial counts and identification of isolates using the BBL Crystal Identification System.
Main Results:
- Pathogen levels initially increased during fermentation but were reduced to undetectable levels after 1 month of aging.
- Total bacterial counts stabilized after 1 month of aging, with no significant changes observed in subsequent months.
- Dominant microorganisms identified in experimental and commercial sufu included Bacillus spp. and Enterococcus spp.
Conclusions:
- Sufu fermentation and aging processes effectively control common foodborne pathogens, ensuring product safety.
- Sufu can be considered a safe food product even without pasteurization.
- Aging may contribute to sufu flavor development, although it does not significantly alter bacterial counts.