Kimchi refers to a group of traditional Korean fermented vegetable products consumed worldwide
[1]. Dating back to the 12th century during the Three Kingdoms period of ancient Korea, salted and fermented vegetable products represent the earliest form of kimchi, however, the addition of several ingredients such as the introduction of red peppers in the 16th century was eventually adopted for kimchi production
[2]. The availability of local ingredients across different provinces in Korea led to the development of many regional kimchi varieties
[3] (Figure 1). Currently, there are over 200 varieties of kimchi with over 100 different ingredients used for kimchi production
[4]. Each kimchi variety is categorized according to the ingredients selected for production
[5]. Kimchi in its current form has been recognized globally through international standardization as well
[6]. Kimchi is prepared by trimming Napa cabbage, followed by salting, rinsing, and then draining excess water. The seasoning ingredients include red pepper powder, garlic, ginger, radish, glutinous rice paste, sugar,
Jeotgal, and
Aekjeot. The salted Napa cabbage is then mixed with the seasoning and stored at low temperatures (typically 0–10 °C in Korea
[5]) to ferment until ripened
[6]. While the production method described by the Codex only describes
Baechu kimchi (Napa cabbage kimchi), slight variations are used to produce other kimchi varieties.
Nonetheless, nearly every kimchi variety benefits from preliminary brining, which inhibits the growth of pathogenic bacteria while selecting for lactic acid bacteria (LAB) known for promoting beneficial effects such as gastrointestinal regulation and prevention of colon cancer
[7,8][7][8]. The LAB such as
Leuconostoc,
Lactobacillus, and
Weissella species as well as the enzymes present in the ingredients are responsible for kimchi fermentation
[9,10][9][10]. Consumption of kimchi is reported to provide numerous health benefits such as anti-oxidative, anti-carcinogenic, anti-mutagenic, and anti-aging effects
[8,11,12][8][11][12].
Despite the numerous beneficial functional qualities, fermented foods such as kimchi may contain potentially harmful substances known as biogenic amines (BA). The nitrogenous compounds are mostly produced by microorganisms during fermentation through enzymatic decarboxylation of amino acids, as well as transamination of ketones and aldehydes
[13]. BA are often categorized as aliphatic: putrescine, cadaverine, spermidine, spermine; aromatic:
β-phenylethylamine, tyramine; heterocyclic: tryptamine, histamine
[14,15][14][15]. The intake of BA at high concentrations as well as amine oxidase inhibition and deficiency may lead to toxic effects
[16]. Recently, histamine, tyramine, putrescine, cadaverine, spermidine, and spermine were found to be cytotoxic toward human intestinal cells
[17,18,19][17][18][19]. Furthermore, BA may also be converted to potentially carcinogenic N-nitrosamines in the presence of nitrites
[20,21][20][21]. Excessive intake of foods containing high concentrations of histamine may potentially induce “scombroid poisoning” with symptoms such as headaches, hives, diarrhea, dyspnea, and hypotension
[22]. Similarly, ingestion of foods with excessive tyramine content may cause a “cheese crisis” with symptoms that include severe headaches, hemorrhages, hypertensive effects or even heart failure
[23]. As a result, many countries have implemented regulations on the production of histamine-rich seafood products, however many other food products are not currently regulated
[24]. Several studies have suggested limits for BA content in food products of 100 mg/kg for histamine, 100–800 mg/kg for tyramine, 30 mg/kg for
β-phenylethylamine, and 1000 mg/kg for total BA content
[14,15][14][15]. The concentrations of BA in many fermented food products such as fermented meats and cheese have been widely reported to exceed limits for safe consumption. Similarly, BA have been detected in kimchi products, the most widely consumed traditional Korean food. High concentrations of BA have also been detected in kimchi ingredients
Jeotgal (Korean fermented seafood) and
Aekjeot (Korean fermented fish sauce), which contribute to the overall BA content in kimchi
[25]. In addition, microorganisms isolated from kimchi as well as the fermented seafood products
Jeotgal and
Aekjeot have been reported to produce BA. Current regulations remain insufficient to address the potential health risks associated with the consumption of kimchi with high concentrations of BA. Therefore, the current article evaluated the risks associated with the BA content of kimchi products according to intake limits for
β-phenylethylamine (30 mg/kg), histamine (100 mg/kg), and tyramine (100 mg/kg) as recommended by Ten Brink et al.
[15], and reviewed potential sources of BA, and methods for reducing BA content.