Determination of biogenic amine-producing lactic acid bacteria in kimchi varieties through in vitro analysis and low temperature fermentation.

This study analyzed biogenic amine (BA) content in three varieties (types) of kimchi (Baechu kimchi, Baek kimchi, and Yeolmu kimchi), identified the causative bacteria, and evaluated the gene expression associated with the BA formation during kimchi fermentation at 4 °C. Histamine content exceeding the toxicity limit was detected in a single Baechu kimchi product. Tyramine content in most Baechu kimchi products was approximately half of the toxicity limit. Other varieties had relatively lower BA content. Most BA producers isolated from all kimchi varieties were identified as Levilactobacillus brevis, which prominently produced tyramine. To clarify the role of L. brevis in tyramine formation in Baechu kimchi, fermentation experiments were performed using L. brevis BC1M20. The results showed that tyramine content and tyrosine decarboxylase gene (tdc) expression were higher in the inoculated kimchi than in the control. In addition, in the inoculated kimchi, the content decreased while the expression level was almost constant. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-024-01627-8.

Occurrence and reduction of biogenic amines in traditional Asian fermented soybean foods: A review.

Biogenic amines are harmful substances generated during the fermentation process. Regulations on biogenic amine content in fermented foods are currently insufficient in comparison to the popularity of fermented food consumption in Asian countries. The current review evaluated the biogenic amine content of fermented soybean-based Asian foods to determine whether the food products are safe for consumption. Though the reported ranges of biogenic amine content in fermented soybean foods varied widely, most products contained biogenic amine concentrations at potentially hazardous levels. To ensure the safety of fermented soybean food products, further efforts are required in the improvement of the food manufacturing process, as well as the establishment of regulations on managing biogenic amine content.

Occurrence and Reduction of Biogenic Amines in Kimchi and Korean Fermented Seafood Products.

Biogenic amines produced during fermentation may be harmful when ingested in high concentrations. As current regulations remain insufficient to ensure the safety of fermented vegetable products, the current study determined the risks associated with the consumption of kimchi by evaluating the biogenic amine concentrations reported by various studies. Upon evaluation, some kimchi products were found to contain histamine and tyramine at potentially hazardous concentrations exceeding the recommended limit of 100 mg/kg for both histamine and tyramine. The biogenic amines may have originated primarily from metabolic activity by microorganisms during fermentation, as well as from Jeotgal (Korean fermented seafood) and Aekjeot (Korean fermented fish sauce) products commonly used as ingredients for kimchi production. Many studies have suggested that Jeotgal and Aekjeot may contribute to the histamine and tyramine content in kimchi. Microorganisms isolated from kimchi and Jeotgal have been reported to produce both histamine and tyramine. Despite the potential toxicological risks, limited research has been conducted on reducing the biogenic amine content of kimchi and Jeotgal products. The regulation and active monitoring of biogenic amine content during kimchi production appear to be necessary to ensure the safety of the fermented vegetable products.

The Occurrence of Biogenic Amines and Determination of Biogenic Amine-Producing Lactic Acid Bacteria in Kkakdugi and Chonggak Kimchi.

In this study, biogenic amine content in two types of fermented radish kimchi (Kkakdugi and Chonggak kimchi) was determined by high performance liquid chromatography (HPLC). While most samples had low levels of biogenic amines, some samples contained histamine content over the toxicity limit. Additionally, significant amounts of total biogenic amines were detected in certain samples due to high levels of putrefactive amines. As one of the significant factors influencing biogenic amine content in both radish kimchi, Myeolchi-aekjoet appeared to be important source of histamine. Besides, tyramine-producing strains of lactic acid bacteria existed in both radish kimchi. Through 16s rRNA sequencing analysis, the dominant species of tyramine-producing strains was identified as Lactobacillus brevis, which suggests that the species is responsible for tyramine formation in both radish kimchi. During fermentation, a higher tyramine accumulation was observed in both radish kimchi when L. brevis strains were used as inocula. The addition of Myeolchi-aekjeot affected the initial concentrations of histamine and cadaverine in both radish kimchi. Therefore, this study suggests that reducing the ratio of Myeolchi-aekjeot to other ingredients (and/or using Myeolchi-aekjeot with low biogenic amine content) and using starter cultures with ability to degrade and/or inability to produce biogenic amines would be effective in reducing biogenic amine content in Kkakdugi and Chonggak kimchi.

Effects of Calcium and Manganese on Sporulation of Bacillus Species Involved in Food Poisoning and Spoilage.

Spores are resistant against many extreme conditions including the disinfection and sterilization methods used in the food industry. Selective prevention of sporulation of Bacillus species is an ongoing challenge for food scientists and fermentation technologists. This study was conducted to evaluate the effects of single and combined supplementation of calcium and manganese on sporulation of common pathogenic and food spoilage Bacillus species: B. cereus, B. licheniformis, B. subtilis and B. coagulans. Sporulation of Bacillus vegetative cells was induced on sporulation media supplemented with diverse concentrations of the minerals. Under the various mineral supplementation conditions, the degree of sporulation was quantified with colonies formed by the Bacillus spores. The results revealed that B. licheniformis and B. cereus displayed the weakest sporulation capabilities on media with minimal supplementation levels of calcium and manganese. The lowest sporulation of B. subtilis and B. coagulans was observed on media supplemented with the highest level of calcium and low levels of manganese. Depending on effect of supplementation on sporulation, the Bacillus species were divided into two distinct groups: B. licheniformis and B. cereus; and B. subtilis and B. coagulans. The information provides valuable insight to selectively reduce sporulation of Bacillus species undesirable in the food industry.