Evaluation of fungal microflora for aflatoxin producing possibility in novel quality Meju fermented with single and/or multiple additions of Nelumbo nucifera, Ginkgo biloba, and Allium sativum extracts

Abstract

This study was aimed to evaluate the fungal microflora in Meju samples fermented using single and/or multiple additions of ethanolic extracts from plants, including Nelumbo nucifera leaves, Ginkgo biloba leaves, and Allium sativum cloves, at different concentrations (1 and 10%) and mixtures of these extracts at a 1:1:1 ratio. Fungal species were grouped based on morphological characteristics, and selected fungal strains were identified based on DNA sequence analysis. Aspergillus species were the dominant microflora in Meju samples. A total of 10 fungal strains isolated from the tested Meju products resulted in the identification of five genera, including Agaricaceae, Aspergillus (synonym: Eurotium), Mucor, Penicillium, and Paecilomyces. Further, Meju samples fermented with selected individual and/or multiple ethanolic extracts resulted in the occurence of various fungal strains, including Aspergillus, Mucor, Paecilomyces, and Penicillium chrysogenum. Conversely, Meju samples fermented without ethanolic extracts as a control resulted in the isolation of Aspergillus ruber, which might be capable of producing aflatoxin B1 and ochratoxin A. The outcome of this study confirms that fermentation of Meju using plant extracts may significantly influence fungal microflora, leading to improved quality of Meju production, because of diminishing effects of the extracts against toxin producing fungal pathogens. Practical applications For decades, fermented foods have been used traditionally as health beneficial products in Asian countries including Korea. Contamination of fermented food starter culture, such as soybean‐based Meju, by pathogenic fungi or toxin producing fungi, such as Aspergillus species, has been reported as a severe concern to consumers. Medicinal plants have shown remarkable efficacy to control a number of pathogenic microbes including fungi. In this study, Nelumbo nucifera leaves, Ginkgo biloba leaves, and Allium sativum cloves exhibited significant potential to diminish the growth of toxin producing fungi, suggesting potential application of medicinal plants for the improved quality of Meju production.

The importance and mitigation of mycotoxins and plant toxins in Southeast Asian fermented foods

“…More investigations on reducing plant toxins in ffs, specifically by fermentation needs to be carried out. In studies carried out by Shukla, et al 46 , plants extracts ( Ginkgo biloba , cloves, and Nelumbo nucifera ), decreased fungal microflora when added during the fermentation of Meju . Aflatoxins are produced by the fungal isolates in Meju , while the addition of the plant extracts during the fermentation process enhanced the shelf-life quality and lowered the toxic effects from the fermented product.…”

“…Aflatoxins are predominantly found in fermented milk products. Different factors influence the free aflatoxins in fermented milk products including storage temperature, storage time, pH, acidity, aflatoxin concentration, and strains used in the fermentation process 46 . Similarly, aflatoxins have been reported in peanut/soybean press cakes such as Indonesian Oncom Hitam and Oncom Merah that are produced using Neurospora sitophila and Rhizopus oligosporus 47 .…”

Toxins in Fermented Foods: Prevalence and Preventions—A Mini Review

“…The results showed that Meju samples contained about ten fungal species, which came under the genera Agaricaceae, Mucor, Penicillium, Aspergillus , and Paecilomyces . Meju prepared without plant extracts contained aflatoxin B1 and the ochratoxin A producing fungus, Aspergillus ruber [26].…”

“…The addition of plant extracts ( Nelumbo nucifera , cloves, and Ginkgo biloba ) reduced the fungal microflora in meju . The fungal isolates can produce aflatoxin in meju , and the fermentation process with plant extracts improved the quality and reduced the toxicity of meju [26].…”

Effects of Radishes, Apples, and Pears on the Lactic Acid Bacteria and Nutritional and Functional Qualities of Flavored Soy Sauce

“…Soybeans (Glycine max), which are a rich source of nutrients, are consumed whole or in the form of fermented products, such as Korean gochujang (a red chilli paste), doenjang (a brined soybean paste), chungukjang (a seasoning paste), and kanjang (soy sauce) [1,2], Japanese miso (a seasoning paste), and Indonesian tempeh (a compressed soybean cake) [3]. In particular, dark-colored salty soy sauces are the most popular fermented products in East Asian countries and are gaining acceptability worldwide due to their unique tastes, aromas, and health benefits [4].…”