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Microbial hazards associated with bean sprouting
Abstract:
The behaviour of microorganisms was studied in mung beans and alfalfa seeds before and after germination in modified, commercially available bean-sprouting kits. The microorganism were enumerated by the aerobic plate count (APC) and by total yeast and mold count procedures. Salmonella species were artificially inoculated into selected samples and were enumerated by the most probable number (MPN) method. After germination of the beans or seeds into mature sprouts, significant increases were noted in APCs and in MPN values of Salmonella species. Although counts of yeasts and molds did not increase significantly after germination, these samples show an increase in toxic Aspergillus flavus and potentially toxic Alternaria species. The presence of toxic Penicillium cyclopium molds also increase substantially in 5 samples of a single brand of mung beans. Analysis of selected sprout samples, however, showed no presence of aflatoxin.
Insights
Sprouting mung beans and alfalfa seeds significantly increased harmful bacteria like Salmonella. While yeast and mold counts remained stable, toxic mold species increased, posing potential health risks despite the absence of aflatoxin.
Area of Science:
- Food microbiology
- Microbial safety in sprouts
- Seed germination and microbial ecology
Background:
- Sprouts are increasingly popular but can pose food safety risks.
- Understanding microbial dynamics during sprouting is crucial for consumer safety.
- Commercial sprouting kits may influence microbial growth patterns.
Purpose of the Study:
- To investigate microbial changes in mung beans and alfalfa seeds during germination in commercial sprouting kits.
- To quantify the levels of total aerobic bacteria, yeasts, molds, and specific pathogens like Salmonella.
- To assess the prevalence of toxic mold species in sprouts.
Main Methods:
- Enumeration of microorganisms using aerobic plate count (APC) and total yeast and mold counts.
- Artificial inoculation with Salmonella species and quantification via most probable number (MPN) method.
- Microbial analysis of mung beans and alfalfa seeds pre- and post-germination.
Main Results:
- Significant increases in aerobic plate counts (APCs) and Salmonella (MPN) were observed after germination.
- Counts of yeasts and molds did not significantly increase, but toxic species (Aspergillus flavus, Alternaria, Penicillium cyclopium) proliferated.
- Aflatoxin was not detected in analyzed sprout samples, despite the presence of toxic molds.
Conclusions:
- Germination in commercial kits can amplify pathogenic bacteria and toxic molds in sprouts.
- The absence of aflatoxin does not guarantee the safety of sprouts with increased toxic mold presence.
- Further research is needed to mitigate microbial risks associated with sprout consumption.