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

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 12th hour(corresponding to 1~3×10⁷CFU/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 14th hour(corresponding to 0.7~2×10⁸ 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 10⁷ and 10⁸ 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.