Biogenic Amines And Amines-forming Bacillus Species In Paste Products

Biogenic amines（BAs）refer to a series of nitrogenous micromolecules with extensive distribution in fermented food,which are mainly produced through decarboxylation of amino acids by specific microorganisms.Paste is a kind of food produced through co-fermentation,the open production environment and abudnant proteins are suitable for the formation of biogenic amines.The study of biogenic amines in paste products and BAs-forming bacteria is helpful to risk evaluation and controlling food quality.Eight biogenic amines in 38 commercial paste products involving 5 categories were evaluated using high performance liquid chromatography（HPLC）.Meanwhile,physico-chemical properties of the samples were measured.All of the samples with the range from 72.1 to 451.1 mg·kg^-1.As for Bacillus subtilis,6% more BAs were produced in comparison with that from Bacillus amyloliquefaciens.Among them,histamine,β-phenethylamine and tyramine account for the majority amount of detected biogenic amines.Bean pastes contain the highest level of BAs followed by mushroom pastes,hoisin sauces,meat pastes and flour pastes in order.For pastes made from different ingredients,the correlations between BAs and physico-chemical properties are not constant and part of them turn to be significant.BAs derived from raw materials and microbial decarboxylation are analyzed respectively in broad bean paste.During the fermentation process,64 strains with potential decarboxylation ability were isolated by selective medium from Chinese traditional broad bean paste mash and identified as Bacillus Species later.The values of total eight BAs produced by strains ranged from 1.09 to 70.14 mg·L^-1 in decarboxylase culture.Arginine decarboxylase（ADC）gene speA,S-adenosylmethlonine decarboxylase（SAMDC）gene speD and lysine decarboxylase（LDC）gene yaaO were found in 43,61 and 50 strains.According to the decarboxylase genes and putative proteins from Bacillus amyloliquefaciens 1-13 and Bacillus subtilis 2-8,alignments were run for determining conserved regions.The phylogenetic tree was constructed simultaneously.The difference of BAs generated by the strain B.amyloliquefaciens 1-13 under different levels of salinity,temperature,oxygen content and amino acid concentration,pH and fermentation time were discussed and temperature turned to be the most remarkable factor.The strain B.amyloliquefaciens 1-13 was inoculated into broad bean paste mash for solid fermentation experiments.BAs contents and related physicochemical parameters along with the change of time series were traced and monitored simultaneously.The ARIMA prediction model of biogenic amine was constructed with data from 2 months’ fermentation.It was revealed that BAs values increased by 61.2 mg·kg^-1 every 10 days at 45℃,which was nearly 3 times that at 25℃.According to the test data and prediction result,400 mg·kg^-1 total BAs was set as the critical value.Exceeding this value represents extremely high risk of rapid increasement of BAs and precautions need to be taken as soon as possible.