Effect of pre-rigor stretch and various constant temperatures on the rate of post-mortem pH fall, rigor mortis and some quality traits of excised porcine biceps femoris muscle strips

Declined flesh quality resulting from niacin deficiency is associated with elevated glycolysis and impaired mitochondrial homeostasis in grass carp (Ctenopharyngodon idella)

Energy metabolism exerts profound impacts on flesh quality. Niacin can be transformed into nicotinamide adenine dinucleotide (NAD), which is indispensable to energy metabolism. To investigate whether niacin deficiency could affect energy metabolism and flesh quality, six diets with graded levels of 0.49, 9.30, 21.30, 33.30, 45.30 and 57.30 mg/kg niacin were fed to grass carp (Ctenopharyngodon idella) for 63 days. The results showed that niacin deficiency declined flesh quality by changing amino acid and fatty acid profiles, decreasing shear force, increasing cooking loss and accelerating pH decline. The accelerated pH decline might be associated with enhanced glycolysis as evident by increased hexokinase (HK), pyruvate kinase (PK) and lactic dehydrogenase (LDH) activities, and mitochondrial dysfunction as evident by destroyed mitochondrial morphology, impaired respiratory chain complex I and antioxidant ability. Based on PWG and cooking loss, the niacin requirements for sub-adult grass carp were 31.95 mg/kg and 29.66 mg/kg diet, respectively.

Muscle structure, sarcomere length and influences on meat quality: A review

The basic contractile unit of muscle, the sarcomere, will contract as the muscle goes into rigor post-mortem. Depending on the conditions, such as the rate of pH decline, the cooling rate and the mechanical restraints on the muscles, this longitudinal shortening will result in various post-mortem sarcomere lengths as well as lateral differences in the distances between the myosin and actin filaments. This shortening is underlying the phenomena described as rigor contraction, thaw rigor, cold shortening and heat shortening. The shortening in combination with the molecular architecture of the sarcomere as defined by the myosin filaments and their S-1 and S-2 units, the interaction with the actin filaments, and the boundaries formed by the Z-disks will subsequently influence basic meat quality traits including tenderness and water-holding capacity. Biochemical reactions from proteolysis and glycogen metabolism interrelate with the sarcomere length in a complex manner. The sarcomere length is also influencing the eating quality of cooked meat and the water-holding in meat products.

Properties of raw meat and meat curry from spent goat in relation with post-mortem handling conditions

The properties of raw meat and meat curry from spent goat meat in relation with post-mortem handling conditions were evaluated. The conditions evaluated were: cooking of meat within 1-2 h post-slaughter (condition 1); deboning meat storage at 25 ± 2 °C for 5-6 h and cooking (condition 2); post-slaughter storage of carcass at room temperature for 5-6 h, then deboning followed by storage of meat at refrigeration temperature for 5-6 h and cooking (condition 3); deboning and storage of meat at 25 ± 2 °C for 10-12 h and cooking (condition 4). Significant difference was observed in pH values in condition 1 (p < 0.01) and moisture content (p < 0.05) of raw meat as compared to the conditions 2, 3 and 4. However, the moisture content of cooked meat was significantly higher (p < 0.05) for conditions 1 and 2 as compared to the conditions 3 and 4. Significant differences were also observed in muscle fiber diameter values of different conditions, that is, the mean values were significantly higher (p < 0.05) for conditions 2 and 4 and significantly lower for condition 1. The mean water holding capacity and cooking yield values were highest in condition 1, followed by conditions 2, 3 and 4. The significant differences was also observed in shear force value of cooked meat chunks, that is, the mean value was significantly higher (p < 0.01) for condition 2 and significantly lower for condition 1. Sensory scores were significantly higher in condition 1 and significantly lower in condition 2. However, sensory scores for condition 4 were almost similar to the condition 1.

Effect of post-mortem handling conditions on the quality of spent hen meat curry

Study was performed to determine the effect of post-mortem handling conditions on the physico-chemical and sensory attributes of spent hen meat curry. Breast cuts of spent hens were subjected to different postmortem handling conditions before cooking viz; made into small cuts and cooked within 1-2 h of slaughter (condition 1), made into small cuts and cooked after 4-5 h of slaughter (condition 2), made into small cuts immediately after slaughter, stored at 4 ± 1 °C for 12 h and then cooked (condition 3), stored at 4 ± 1 °C for 12 h, made into small cuts and cooked (condition 4). The pH of meat just before cooking due to different stages of rigor development under various conditions differed accordingly. Observed differences in temperature of meat just before cooking were because of different postmortem handling condition variations viz:1,2,3,&4. The associated post mortem changes under different postmortem handling conditions before cooking led to significant variation in Water holding capacity, Water Soluble Protein, Salt Soluble Protein, cooking yield, moisture percentage before cooking and after cooking and also WB shear force value. In general, sensory scores were higher for conditions 4 and 1 as compared to conditions 2 and 3. Results revealed that quality attributes of spent hen meat curry can be improved by following proper post-slaughter handling and processing conditions. To get meat curry of good sensory quality, meat should be cooked preferably within 1-2 h of slaughter or after 10-12 h of storage of intact carcass at 4 ± 1 °C. Cuts should be made just before cooking but cooking after 4-5 h of slaughter should be avoided.