As storage time increased, the pH for MAP and VP treatments decreased during storage. An increase in pH was determined at day 7 for PVC treatments (Table 3).The decrease in meat pH for MAP and VP treatments was attributed largely to the presence of dissolved CO2 and growth of LAB in the meat. The modified atmosphere used in this study contained 30% CO2 which is the active antimicrobial agent in both anaerobic MAP and VP (Sebranek & Houser, 2006). When CO2 is introduced into the headspace of a package, its concentration will decline as CO2 is absorbed into themeat. Dixon and Kell (1989) reported that CO2 gas dissolves readily into the aqueous phase of the meat and produce carbonic acid (H2CO3) which results in decreased meat pH and microbial growth. Carbon dioxide usually results in a decrease in pH of 0.05–0.35 units in the meat product (Huffman, Davis, Marple, & McGuire, 1975; Rousset & Renerre, 1991). The increase in pH observed in all PVC treatments may have been caused by production of alkaline by-products during growth
and stationary phase of the microorganisms.
As storage time increased, the pH for MAP and VP treatments decreased during storage. An increase in pH was determined at day 7 for PVC treatments (Table 3).The decrease in meat pH for MAP and VP treatments was attributed largely to the presence of dissolved CO2 and growth of LAB in the meat. The modified atmosphere used in this study contained 30% CO2 which is the active antimicrobial agent in both anaerobic MAP and VP (Sebranek & Houser, 2006). When CO2 is introduced into the headspace of a package, its concentration will decline as CO2 is absorbed into themeat. Dixon and Kell (1989) reported that CO2 gas dissolves readily into the aqueous phase of the meat and produce carbonic acid (H2CO3) which results in decreased meat pH and microbial growth. Carbon dioxide usually results in a decrease in pH of 0.05–0.35 units in the meat product (Huffman, Davis, Marple, & McGuire, 1975; Rousset & Renerre, 1991). The increase in pH observed in all PVC treatments may have been caused by production of alkaline by-products during growthand stationary phase of the microorganisms.
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