Meju fermented with addition of Nelumbo nucifera , Ginkgo biloba , and Allium sativum

摘要

Meju, a cooked and fermented soy bean based food product, is used as a major ingredient in Korean traditional fermented foods such asDoenjang. We developed a novel type ofMejuusing single and combined extracts ofAllium sativum(garlic clove),Nelumbo nucifera(lotus leaves), andGinkgo biloba(ginkgo leaves) at 1% and 10% concentrations to improve the safety ofMeju-based fermented products. Biogenic amines (BAs) in protein-rich fermented food products pose considerable toxical risks. The objective of this study was to investigate the effects of adding selected plant extracts inMejusamples during fermentation. Nine BAs, including tryptamine, 2-phenylethylamine, putrescine, cadaverine, agmatine, histamine, tyramine, spermidine and spermine, were isolated fromMejusamples after sample derivatization with dansyl chloride and analyzed by high performance liquid chromatography. As a result, all testedMejusamples with added plant extracts showed total BAs levels in the range of 20.12?±?2.03 to 118.42?±?10.68 mg/100?g, which were below the safety limit set by various regulatory authorities (USFDA/KFDA/EFSA). However, among all testedMejusamples, LOM10 (Mejufermented withNelumbo nuciferaat 10% concentration) showed higher levels of BAs content than others either due to batch-to-batch variability or reduced beneficial microorganisms and/or due to increase in BA forming microorganisms. Also, none of the samples showed the aflatoxin level above the detection limit. Furthermore, all the testedMejusamples improved microbial safety as confirmed by the complete absence ofSalmonellaspecies andStaphylococcus aureus. However, some of theMejusamples showed the presence of coliforms (in range of 1.6?×?100–1.1?×?103?CFU/g), which is under regulatory limits. These results suggested that the use of plant extracts inMejuduring fermentation have potential to improve microbial and toxicological safety ofMejuproducts.