1) In this study we investigated the effect of temperature on the two-stage fermentation of Makgeolli using uncooked germinated black rice. The fermentation processes were conducted at 15℃ for three weeks and 25℃ for 7 days. The pH of Makgeolli at 25℃ increased from pH3.0 to pH 4.2, which was consistent with that at 15℃. In contrast total acidity of Makgeolli at 15℃ was about half of that at 25℃ (0.36% and 0.59%, respectively). By the 7 days-fermentation at 25℃, 11% of alcohol was produced, whereas three weeks were required for the same alcohol production at 15℃. In the case of sugar contents, the amounts of total glucose-equivalent reducing sugars and glucose increased at the end of the fermentation at 25℃ up to 2.25 mg/mL and 3.4 mM, respectively, whereas those at 15℃ were maintained at very low levels (0.18 mg/mL and 0.1 mM, respectively). Such limited supplement of sugars at 15℃ seemed to affect metabolism of yeast, resulting in different composition of organic acid. At 25℃, citric acid that was 73.4 ppm at the initial fermentation was consumed completely, whereas 20 ppm of citiric acid was remained at 15℃. In addition, acetic acid and lactic acid in Makgealli at 15℃ were 53% and 14% of those at 25℃.

Biogenic amines have been used as chemical indicators to estimate bacterial spoilage of foods, particularly fish and fish products, cheese, and fermented foods. So far many chromatography methods have been developed to detect biogenic amines in foods. Although these instrumental analyses exhibit good sensitivity, they cannot be used as rapid detection methods due to the chemical treatment of the samples and the time-consuming process involved. For the rapid and simple detection of biogenic amines, enzyme linked immunosorbent assay kits are commercially available. In addition, analytical systems with enzyme-based amperometric biosensor detection have been increasingly developed. The biosensors used to detect the biogenic amines are based on the action of either amine oxidases or amine dehydrogenases that catalyzes the oxidative deamination of biogenic amines to the corresponding aldehydes and ammonia. This review mainly focused on the principle, development, and applications of the detection methods for rapid detection of biogenic amines in foods.

Ten major residual biogenic amines including toxic histamine and tyramine were investigated in the plant-based minor Korean fermented food. From the analyses of pickled vegetables, fermented vegetable extracts, fermented tea, black garlic and herbal rice wines, more than 100 mg/kg of histamine were found in pickled soy leaf and pickled mulberry leaf, and also over 1,000 mg/kg of total biogenic amines were found in pickled soy leaf. No sample was found over in black garlic, fermented tea, fermented vegetable extracts and herbal rice wine, less than 100 mg/kg of histamine and/or 1,000 mg/kg of total biogenic amines were observed. Interestingly, all the tested rice wines were found to be over 100 mg/kg of agmatine residue.