# Advances in Fermentation Technology: A Focus on Health and Safety
## 2 Microbial Control of the Pathogens' Growth--Biocontrol Strategies
### Potential Health Hazards in Traditional Fermentation
#### 2.1.2 Biogenic Amine Formation  
Another potential health hazard in fermented foods is the formation of biogenic amines (BAs), particularly histamine, tyramine, and putrescine, which are produced through amino acid decarboxylation pathways during fermentation [27]. This biochemical process is catalysed by substrate-specific decarboxylase enzymes produced by certain bacteria, fungi, or yeasts; recent studies have identified that typical genes for decarboxylases targeting histidine, tryptophan, arginine, and ornithine are prevalent in fermented foods. Primary histamine production has also been linked to the _Lactococcus_, _Enterococcus_, and _Lactobacillus_ genera, while tyramine production is predominantly associated with Bacillus and other specific genera [28]. The accumulation of BAs depends on multiple factors, including the substrate availability (free amino acids from proteolysis), the presence of decarboxylase-positive microorganisms (_Staphylococcus_, _Enterobacteriaceae_, and some lactic acid bacteria [LAB]), and environmental conditions such as temperature, pH, and oxygen levels. Elevated temperatures (25-37 \({}^{\circ}\)C) and anaerobic conditions typically promote BA-producing LAB; on the other hand, acidic environments (pH < 5.0) can induce microbial decarboxylase activity as a mechanism for pH regulation [29; 30; 31]. For example, fish sauce fermentation studies reported histamine levels exceeded the FDA limit of 50 mg/kg after 12 months, reaching 55.59 mg/kg. Notably, the accumulation of BAs is primarily attributed to dominant bacteria, such as _Tetragenococcus_ and _Halomonas_, present in fish sauce [32]. Another research on Cambodian fermented fish products revealed that some samples contained histamine levels above the FDA guideline [33]. Elevated BA concentrations characterize meat sausages and fish sauces. Research has demonstrated that tyramine levels are particularly significant in luncheon meats, while high levels of cadaverine have been detected in cored beef. The biogenic amine index (BAI) serves as a vital criterion for assessing the quality of meat products, categorizing them as follows: spoiled (BAI > 50 mg/kg), poor quality (BAI 20-50 mg/kg), acceptable (BAI 5-20 mg/kg), and good quality (BAI < 5 mg/kg) [34]. Furthermore, a study conducted by [PERSON] et al. [35] revealed that domestically ripened cheeses exhibit notable total BA levels, with cheddar reaching 257.71 mg/kg and semi-hard Gouda ranging from 292.79 to 384.33 mg/kg. In stark contrast, imported ripened cheeses demonstrate even more concerning BA concentrations; for instance, Pecorino Ro mano showed a frightening total BA level of 1889.75 mg/kg, while Grana Padano recorded 1237.80 mg/kg, both surpassing the 1000 mg/kg threshold. In these imported varieties, histamine constituted approximately 86% of the total BA content in Pecorino Romano and 77% in Grana Padano. Another study further identified considerable variability in the average BA levels in fermented vegetables available in the Polish retail market, with the total BAs measured ranging from 30.29 \(\pm\) 16.43 mg/kg in fermented olives to 612.1 \(\pm\) 359.33 mg/kg in fermented Brussels sprouts. The BA profiles were predominantly composed of putrescine (42%), tyramine (20%), cadaverine (18%), and histamine (8%), cumulatively accounting for 88% of the nine studied BAs. Consequently, excessive BA consumption can lead to adverse reactions such as migraines, tachycardia, cardiovascular issues, respiratory problems, gastrointestinal disturbances, headaches, and allergic responses in sensitive individuals [36]. To address this issue, studies have identified potential starter cultures with high BA reduction capabilities to mitigate these risks, including _Staphylococcus nepalensis_ and _S. xylosus_ and a selection of strains of microorganisms that do not produce or have a low probability of synthesizing biogenic amines [32].