As part of the Master's thesis, we determined the content of biogenic amines (BA), gamma-aminobutanoic acid (GABA) and the content of free phenolic compounds in different types of tempeh and in natto. Using the Folin-Ciocalteau method, we found that fermentation of all investigated tempeh and natto samples resulted in a higher content of free phenolic compounds. Chromatographic analysis of derivatized tryptamine, phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermine, spermidine and GABA with dansyl chloride was applied to determine their content before and after fermentation and after storage in the refrigerator (5 and 19 days, at 4 °C). We found that the GABA content in the non-fermented samples was relatively low, as it did not exceed 250 mg/kg. After fermentation, the GABA content increased in all analyzed tempeh samples, while storage did not show an uniform response regarding GABA formation/degradation. After storage, a higher GABA content was measured in most of the tempeh samples, with the exception of the tempeh made from buckwheat and sunflower seeds, where a decrease was observed. All tempeh samples had a higher spermidine content than spermine. Storage of tempeh in the refrigerator resulted in the decrease in spermidine and spermine content, except for tempeh made from buckwheat and sunflower seeds, where higher values were determined after 19 days of storage. Putrescine, cadaverine and tyramine were the predominant BA in the analyzed samples. Putrescine accumulated in all analyzed samples and was the quantitatively most important BA in the majority of samples. The highest content was found in tempeh made from lentils and beans (117,3 mg/kg). The storage of tempeh in the refrigerator has an effect on the content of some BA. The most significant change was observed for cadaverine, the content of which increased 100 times (to 466,9 mg/kg) in tempeh made from lentils and beans after 19 days of storage. We found a positive correlation between total BA and GABA content, with the best correlation being between GABA and putrescine content. In the natto samples, we did not observe any major differences in the content of GABA, polyamines and BA after fermentation and during storage.
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