熟畜肉中金黄色葡萄球菌污染标记物动态变化及与菌体生长关联分析

The Variation Characteristics of the Volatile Markers and Its Relation to Growth Status of Staphylococcus aureus Growing on Cooked Meats

为考察不同类型的熟猪肉、牛肉、羊肉对金黄色葡萄球菌污染标记物的影响,采用顶空固相微萃取/气相色谱质谱联用技术对三种熟肉进行本底值检测,并对人工染菌的三种熟肉进行标记物动态分析和细菌生长数量变化测定。结果表明,在采集的大量样本中,三种熟肉基质都检出一定强度的3-甲基丁醛和3-甲基丁酸信号,作为熟畜肉的本底值。对于受金黄色葡萄球菌污染的三种熟肉,3-甲基丁醛信号均在第12 h时(1～3×10~7 CFU/g)出现显著增长(p<0.05),强度增长到最大值后迅速下降;3-甲基丁酸信号均在第14 h时(0.7～2×10~8CFU/g)出现显著增长(p<0.05),在整个培养过程中强度不断上升。对于三种熟肉,3-甲基丁醛(0～18 h)和3-甲基丁酸(0～24 h)的信号强度分别与金黄色葡萄球菌生长量之间均具有极显著(p<0.01)的相关性。结论:金黄色葡萄球菌生长量分别达到10~7、10~8 CFU/g时开始检测到3-甲基丁醛和3-甲基丁酸的增长,之后在一定的培养周期内这两个物质稳定存在并与菌体生长显著相关。研究结果为建立畜肉中金黄色葡萄球菌污染标记物检测技术奠定了前期基础。

To explore the influences of different meats on the volatile markers of Staphylococcus aureus contaminating on cooked meat,headspace-solid phase micro-extraction/gas chromatography-mass spectrometry(HS-SPME-GC/MS)was employed to measure the background values of three cooked meats(pork,beef and mutton)and production regularities of volatile markers of S.aureus growing on meats.The growth of S.aureus was determined by enumerating bacterial cells.The results showed that all of three cooked meat were detected both 3-methyl-butanal and 3-methyl-butanoic acid signals,so that the contamination of S.aureus on meat could be judged by the detection value obvious above meat background values.For S.aureus growing on these three cooked meats,the 3-methyl-butanal signal increased significantly(p<0.05)at the 12 th hour(corresponding to 1~3×10~7CFU/g),then it showed an increase up to the maximum with a sharp decrease.The 3-methyl-butanoic acid signal increased significantly(p<0.05)at the 14 th hour(corresponding to 0.7~2×10~8 CFU/g),then increased continuously during the whole incubation process.And the correlation between 3-methyl-butanal intensities and bacterial counts of S.aureus were extremly significant during 0~18 h,also the correlation between 3-methyl-butanoci acid intensities and bacterial counts of S.aureus were extremly significant during 0~24 h(p<0.01).Therefore,the increasing of 3-methyl-butanal and 3-methyl-butanoic acid was detected while the bacterial cells of S.aureus reached up to 10~7 and 10~8 CFU/g respectively.Subsequently,the two volatile markers were stable and significantly correlative with bacterial counts of S.aureus during a certain period of incubation.These results provided foundations for the establishment of the detection of S.aureus contaminating on meat based on volatile markers.