Study On Superchilling Storage Technology Of Rabbit Meat

Rabbit meat is rich in nutritional value with high protein, lysine and digestibility characteristics, as well as low fat, cholesterol and calorie characteristics, often referred to as “health, beauty and mentality improving food”. China is the largest producer and exporter of rabbit meat around the world. Facing increasing demands on freshness, safety and nutrition on rabbit meat products from consumers, the preservation technology of fresh rabbit meat during transport and sales process is becoming increasingly important. The program was based on research object of Ira rabbit hind legs and longissimus muscle and the following aspects were studied:(1)It was studied that the effects of chilling storage(4 ℃) and superchilling storage(-2.5 and-4 ℃) of tray packaged Ira rabbit hind legs and longissimus muscle on freshness, physical quality and muscle histology. The results showed that: as the storage time increased, the TAC, TVB-N and TBARS value of all groups increased significantly(P<0.05), but sensory scores of all groups decreased; the pH value increased firstly and then decreased. The drip loss, cooking loss, b * value and adhesiveness experienced an increase overall while L * and a * value, shear force, hardness and springiness showed a downward trend. With the extension of storage time and the decrease of storage temperature, the size of gap and number in cells presented an upward trend while myofibrillar exhibited separation or even fracture trend. Considering results above, we can make a conclusion that compared with the short shelf life of chilling storage(6 d), superchilling storage at-4 ℃ can extend the shelf life over 30 days, superchilling storage at-2.5 ℃ can extend the shelf life to 14~18 d. The results of this study indicate that superchilling storage can significantly inhibit the activity of endogenous enzyme and the reproduction of spoilage microorganisms, thus extending the shelf life of rabbit meat and keeping better sensory and nutritional quality; although the shelf life of superchilling storage at-4 ℃ is longer than superchilling storage at-2.5 ℃, it will cause more serious damage to the muscle tissue structure.(2)It was studied that the effects of chilling storage(4 ℃) and superchilling storage(-2.5 and-4 ℃) of tray packaged Ira rabbit hind legs on protein structure, functionality and heat-induced protein gel properties. The results showed that: as the storage time increased, total sulfhydryl and active sulfhydryl content in salt-soluble protein of three groups decreased significantly(P<0.05), while carbonyl content increased significantly. Salt-soluble protein surface hydrophobicity of all groups showed a marked increase; EAI and ESI value were both declining firstly and then rising. Both hardness and water holding capacity of heat-induced gel showed a significantly downward trend; the storage modulus(G ’) of the salt-soluble protein showed the three-step change “up- down- up”. Considering SDS-PAGE analysis and results above, compared with chilling storage(4 ℃), superchilling storage(both-2.5 and-4 ℃) can significantly slow down the rate of protein deterioration occurred in the structure, functionality and gel properties. The lower the superchilling storage temperature was, the slower the rate of deterioration was. Correlation analysis showed that changes occurred in the functionality and gel properties during storage have significant correlation with changes occurred in protein structure.(3)It was studied that the effects of vacuum packaging and modified atmosphere packaging(MAP)(the percentage of gas CO2: O2: N2 = 45: 45: 10)(the CK is air packaging) on freshness, physical quality and fatty acid composition of rabbit hind legs superchilled at-2.5 ℃. The results showed that: as the storage time increased, TAC, TVB-N and TBARS value of three groups increased significantly(P<0.05), but sensory scores of all groups decreased; the pH value was rising firstly and then declining. L * value, hardness, springiness and chewiness showed a gradual downward trend while drip loss, cooking loss, b * value and adhesiveness showed a gradual increase overall; a * value of MAP samples increased to the maximum firstly and then decreased gradually. With the extension of storage time, PUFA decreased significantly while SFA showed a gradual upward trend. During the 30 days’ storage period, the most serious fatty acid oxidation occurred in MAP group, while the lightest fatty acid oxidation occurred in vacuum packaging group, which was consistent with results of TBARS analysis. Considering results above, we can make a conclusion that compared with the CK group(with shelf life 20~25 d), both MAP and vacuum packaging group can reach more than 30-day shelf life. The results of this study indicate that both MAP(containing 45% CO2) and vacuum packaging could inhibit the growth and reproduction of spoilage microorganisms, thus extending the shelf life of rabbit meat; the vacuum packaging can significantly inhibit lipid oxidation. Although the MAP is able to make superchilled rabbit meat maintain bright red close to 30 days, it could accelerate lipid oxidation.(4)It was studied that the effects of 0.1% and 0.2% tea polyphenols(TP)(distilled water as CK) on freshness, physical quality and fatty acid composition of rabbit longissimus dorsi superchilled at-2.5 ℃. The results showed that: as the storage time increased, TAC, TVB-N and TBARS value of all groups increased significantly(P<0.05), but sensory scores of all groups decreased; the pH value was rising firstly and then declining. Drip loss, cooking loss, b * value and adhesiveness showed a gradual increase overall while L * and a * value, hardness, springiness and chewiness showed a downward trend. With the extension of storage time, PUFA decreased significantly while SFA showed an upward trend. Considering results above, we can make a conclusion that compared with the CK group(with shelf life 20~25 d), both 0.1% and 0.2% TP groups can reach more than 30-days shelf life. The results of this study indicate that both 0.1% and 0.2% TP solution are able to inhibit fatty acid oxidation and therefore extended the shelf life of superchilled rabbit longissimus dorsi. The antibacterial and antioxidant effects of 0.2% TP are significantly better than 0.1% TP, which is basically consistent with results of TAC, TVB-N and TBARS.