Research And Control Of Factors Affecting Biogenic Amines Content In Chinese Dry Fermented Sausages

Effects of different factors on the biogenic amines(histamine, tyramine and tryptamine)content in Chinese dry fermented sausage and the mechanism of starter culture in reducing the biogenic amine content were studied. Sausages of good flavor and histamine content lower than 50mg/kg were made.First, the influence of different hygienic quality of raw materials on biogenic amines production during fermenting and ripening of dry fermented sausages were studied. Analysis methods and extraction chemicals of biogenic amines in dry fermented sausages were also studied and selected. The results showed that the percentage of amine extraction of TCA was the highest among TCA, HClO₄ and sulfonic salicylic. Biogenic amines can be determined and separated well as OPA derivates with HPLC method. The detection limit of histamine, tyramine and tryptamine was 0.05, 0.08 and 0.1mg/kg separately. The relative standard deviation(n=8) of histamine, tyramine and tryptamine was 1.2%, 1.5% and 1.5% orderly. The average recovery of histamine, tyramine and tryptamine was 98.1%, 86.2% and 96.0% respectively. The dependent coefficient of the linear function was 0.9996, 0.9994 and 0.9992 orderly. Naturally fermented sausages made with raw meat of Enterobacteriaceae counts less than 3 log(CFU/g), histamine and tyramine content less than 5mg/kg DM and the VBN content less than 43.5 mg/100g can have histamine and tyramine content less than 50mg/kgDM and 300mg/kgDM respectively.Second, effects of Lactobacillus casei, Pediococcus pentocaceus, Lactobacillus plantarum and Staphylococcus xylosus as single starters or mixed starters separated from Chinese traditional sausages on biogenic amines production during ripening of dry fermented sausages were studied. The results showed that Lactobacillus casei as a single starter culture can reduce the concentration of histamine and tyramine by 68.1% and 11.6% comparing to the controlled batch. Staphylococcus xylosus can reduce the content of histamine by 41.0% comparing to the controlled batch. Mixed starter culture of Lactobacillus casei and Staphylococcus xylosus showed more effect on reducing histamine and tryptamine contents than the single starters. The content of histamine can be decreased by 94.2% and tryptamine by 13.07% comparing to the controlled batches. Pediococcus pentocaceus can reduce the content of histamine, tyramine and tryptamine by 95.16%, 24.81% and 34.4%. Mixed starter culture of Pediococcus pentocaceus and Staphylococcus xylosus showed more effect on reducing tyramine and tryptamine contents than the single starters. The concentration of tyramine can be decreased by 29.53% and tryptamine by 46.59% comparing to the controlled batches. Lactobacillus plantarum cannot decrease the concentration of biogenic amines in fermented sausages. Lactobacillus plantarum cannot reduce the content of those three biogenic amines even mixed with Staphylococcus xylosus.Changes in microbe's counts, pH and water content during fermentation were also analyzed to see the mechanism of starter cultures in reducing the biogenic amines content of fermented sausages. LC+SX can reduce the concentration of histamine and tryptamine more than LC. The reason is that SX can promote the growth of LAB. LC+SX can reduce the concentration of tyramine less than LC. Maybe it is caused by the ability of SX in producing tyramine and also large amounts of Enterobacteriaceae, which can produce high amounts of tyramine. PP+SX reduced the content of histamine less than PP is because of the weak ability of SX in reducing histamine. The ability of PP+SX in reducing tyramine and tryptamine contents more than PP because that SX can promote the growth of PP, which then produced more amine-decomposing enzyme. Enterobacteriaceae can have important effect to the content of tyramine and tryptamine in sausages fermented with LC or SX. Enterobacteriaceae also caused higher histamine content of PP+SX than PP. There is no strong relationship between pH, water content, AAN and VBN with amines content.Chinese fermented sausages were made using starter cultures of PP+SX and LC+SX. The effects of storage conditions on the concentration of biogenic amines were also studied. It showed that sausages fermented with PP+SX and LC+SX can have biogenic amines concentration less than 50mg/kgDM and good flavor. Condition of vacuum can slow the increase of histamine content when sausages were kept in the temperature of 25 ℃, but had little effect on histamine content when sausages were kept in the temperature of 4℃. The condition of vacuum and temperature had strong effect on tyramine content. The concentration of tryptamine can increased when sausages were kept in 25 ℃. Condition of vacuum have little effect on the content of tryptamine in dry fermented sausages.