原料肉贮藏时间对牛肉发酵香肠中微生物菌相变化和蛋白质降解的影响

采用传统微生物计数、高通量测序、凯氏定氮、高效液相色谱等方法，探究牛肉宰后0～4 ℃下不同贮藏时间（0、12、24、36 h）对发酵香肠加工过程中微生物菌相变化、蛋白质降解及其相关性的影响。结果显示，随着牛肉贮藏时间的延长，香肠中菌落总数、大肠菌群数、菌群多样性和丰富度以及蛋白质降解指标均呈上升趋势，总游离氨基酸含量呈下降趋势；香肠成熟阶段中总挥发性盐基氮含量与总生物胺含量之间呈极显著正相关（P＜0.01）。其中，贮藏36 h牛肉加工的香肠与未经贮藏牛肉加工的香肠对比，菌落总数平均值由2.40×107 CFU/g增加到4.03×107 CFU/g（P＜0.05），反映菌群多样性的Shannon指数平均值由1.39增长至2.89，优势菌群由整个加工阶段均为葡萄球菌变成前期为魏斯氏菌，后期为葡萄球菌；总游离氨基酸含量平均值由7.09 mg/g减少至6.44 mg/g，总生物胺含量平均值由92.14 mg/kg增长为117.42 mg/kg（P＜0.05）。结论：控制原料牛肉贮藏时间可以有效减少香肠中微生物的总量，降低菌群多样性，抑制蛋白质的降解，减缓生物胺的积累，从而保障发酵香肠的安全性。

Effects of Storage Time of Raw Beef on Microflora Changes and Protein Degradation in Fermented Beef Sausages

Traditional microbial counting methods, high-throughput sequencing, the Kjeldahl method and high performance liquid chromatography (HPLC) were applied to explore the effects of different postmortem storage times of beef (0, 12, 24 and 36 h at 0–4 ℃) on microflora changes and proteolysis during the processing of fermented beef sausages as well as on the correlation between them. The results showed that the total number of bacterial colonies, coliform count, the diversity and richness of bacterial communities and proteolysis indexes increased, while the content of total free amino acids in fermented beef sausages decreased as the storage time of raw beef increased. A significant positive correlation appeared between total volatile basic nitrogen (TVB-N) and total biogenic amine contents during the ripening process (P < 0.01). The average values of total number of bacterial colonies and Shannon?diversity index of fermented sausage prepared from 36 h-chilled beef were 4.03 × 107 CFU/g and 2.89, respectively, which were both higher than those (2.40 × 107 CFU/g and 1.39) of fermented sausage prepared from unchilled fresh beef (P < 0.05 for total number of bacterial colonies). The dominant bacteria in the former were Staphylococcus over the whole processing period, while the dominant bacteria in the latter were Weissella spp. at the early stage and Staphylococcus at the late stage. The average total free amino acid content decreased from 7.09 to 6.44 mg/g, whereas the average total biogenic amine content increased from 92.14 to 117.42 mg/kg (P < 0.05). These results indicated that controlling the storage time of raw beef could effectively reduce the total microbial load and the microbial diversity of fermented sausages, retard the accumulation of biogenic amines and inhibit proteolysis, thereby ensuring the safety of fermented sausages.