MICROBIOLOGICAL QUALITY OF FROZEN “EDAMAME” (VEGETABLE SOYBEAN)

ABSTRACT This study compared the microbiological quality of frozen “edamame” to other varieties of frozen beans sold in Virginia. Furthermore, the reduction of microorganisms during experimental edamame processing was investigated. Commercial frozen in-pod and shelled edamame had aerobic mesophiles at 3.4 and 3.1 log cfu/g, yeasts and molds at 2.3 and 2.1 log cfu/g, and some contained low levels of Escherichia coli and enterotoxigenic Bacillus spp. Salmonellae were not found; however, 5% edamame and 4% frozen beans in general were positive for Listeria monocytogenes. Rinsing and shelling raw edamame caused a 1–2 log reduction of total aerobic mesophile, yeast and mold, and coliform counts. No naturally occurring yeast, mold or coliform was detected after blanching edamame at 98C for≥30 s. Blanching for 60 s eliminated approximately 6 log cfu/g of inoculated E. coli and Listeria from in-pod edamame. Adequate processing ensures the microbial quality and safety of frozen edamame. PRACTICAL APPLICATIONS Frozen “edamame” has the potential to be produced with microbial quality acceptable for direct consumption. However, current products may contain harmful bacteria such as Escherichia coli and Listeria monocytogenes; thus, thorough reheating is required for consumer safety. Strict sanitation and effective blanching practices are critical in assuring microbial quality and safety of frozen edamame. Data reported for the first time from this current study could be used to inform frozen edamame producers and consumers of the potentially associated microbial hazards and adequate means for food protection.