Improvement of Oxidation Stability of Enhanced Pork Loin by Red Perilla Leaf Extract

Abstract

The aim of this study was to produce the enhanced meat with the improvement of oxidation stability by injecting natural antioxidant into the pork loin. Three experiments were performed as below. Experiment I: The natural antioxidants derived from tomato (Solanum lycopersicum), broccoli (Brassica oleracea var. italica), burdock (Arctium lappa), and red perilla leaf (Perilla frutescens var. acuta) were prepared by hot water extraction followed by lyophilization. The antioxidant activity was evaluated by total phenolic content, DPPH radical scavenging activity, and reducing power. The total phenolic compound was the highest in the extract of red perilla leaf (71.76 ± 2.112 mg GAE /g). The extract of red perilla leaf (Perilla frutescens var. acuta) (ERP) showed the lowest the half maximal effective concentration (EC50) values of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and reducing power among the extracts of natural plants. The ERP had the highest antioxidant activity. Experiment II: The optimal injection concentration of ERP was evaluated depending on the antioxidant activity of ERP in pork patty. The pork patties were divided into 6 treatment groups: the addition of ERP at 0, 2, 4, 6, 8, and 10 g/kg concentration and measured the content of malondialdehyde (MDA) in cooked pork patty. The MDA content in pork patty added with ERP was significantly lower MDA content than that of pork patty (P˂0.05). However, there was no significant difference of MDA content in pork patties added with ERP at a concentration of 2, 4, 6, 8, and 10 g/kg. As a result, the 2 g/kg and 4 g/kg of ERP were set to appropriate concentrations. Experiment III: The quality properties of pork loin injected with ERP at a concentration of 2 g/kg and 4 g/kg (ERP 2 and ERP 4) were investigated and compared with non-injected pork loin or injection brine containing no ERP (ERP 0). The pH and cooking loss were no significantly different among all treatments. The MDA content of ERP 2 and ERP 4 were significantly lower than that of control and ERP 0 after storage for 4 days in cooked loin (P<0.05). ERP 2 and ERP 4 had lower L*-value and higher a* and b*-values than that of non-injected and ERP 0 in both raw and cooked loins. However, the ERP 4 of odor and off-taste score was the highest among treatments during all storage periods. For these reason, in overall acceptability, the ERP 0 and ERP 4 had the highest and lowest scores, respectively. Also, no significant differences of overall acceptability scores were found among non-injected, ERP 0, and ERP 2 after storage for 7 days. From the all results, the injection of ERP at a concentration of 2 g/kg improved oxidation stability of pork loin during storage without adverse effect. The current study concluded that the production of enhanced pork meat with increase oxidative stability can be possible by the injection of ERP as natural antioxidant.