This study aims to evaluate the effects of spices essential oils (SEOs) on the microbial populations in chilled pork stored in PE film antimicrobial package. The microbiota from the pork under different storage conditions were studied by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) of the V 3 variable region of the 16S rRNA, followed by sequencing of DGGE fragments. We found that SEOs resulted in an overall significant reduction of viable counts of Gram positive bacteria such as Carnobacteria, Enterococcus sp., Staphylococcus sp. and Brochotrix thermosphacta compared to the control. A 2.5 log cycles reduction of enterobacteria was also identified compared to the control during storage, while SEOs had little effect on Pseudomonas sp. the total volatile basic nitrogen (TVBN)and Thiobarbituric acid reactive substance(TBARS) were affected by the use of SEO packages, but color (L*, a*, b*), shear force and cooking loss were not affected. The bacteriostatic effect of clove EO was the best among all the SEOs tested, and the number of spoilage populations decreased with the use of the SEOs, but the species diversity of spoilage microbiota was not affected.Keywords: chilled pork, antimicrobial pack, essential oils, PCR-DGGE, 16S rRNA gene, diversity *To whom correspondence should be addressed. E-mail: liugq_168@163.com
IntroductionChilled pork is the mainstream meat for human consumption, and its proper preservation is essential. During the prolonged storage time, the spoilage-related microorganism may inevitably develop in the chilled pork, therefore it is critical to enhance the antispoilage storage condition to minimize such unwanted microbial development. Currently, numerous synthetic anti-microbial reagents are being used for this purpose, however these antimicrobial agents are of various drawbacks including chemical stability, toxicity and limited effectiveness. Another issue in the recent antimicrobial research of meat preservation is that most investigators are focusing on the comparisons between viable counts of spoilage microbial groups, however the type and time of the spoilagemicroorganism development are not well examined. Certain microorganism taxa may be differently influenced by the PE film package with the addition of anti-microbial reagents, but others may develop unpredictably during storage depending on the time and type of spoilage microorganisms. Moreover, within each spoilage microbial group, it is critical to also understand which species are actually involved in the spoilage of meat and how they can interact with other species (Gram et al., 2002).Recently, the spices essential oils (SEOs) have emerged as completely natural alternative antimicrobials reagents in the food industry. In particular, rosemary EO, angelica root EO and clove EO are among the popular ones being actively investigated for their characteristic antimicrobial effects. These different SEOs were found to target different microorganisms. The rosemary EO was found to inhibit the growth of gram-posit...