(1) Meat color: Meat color mainly depends on myoglobin content and chemical state. The evaluation of pork color should be carried out under normal indoor sunlight. Evaluation time: fresh pork 65438+ frozen meat samples were slaughtered 0 ~ 2h24 and 24h after slaughter. The evaluation site is the cross section of latissimus dorsi in thoracolumbar segment.
(2) Tenderness: It is one of the main edible qualities of meat, which refers to the tenderness of meat when eating and reflects the texture of meat, which is determined by various protein structures in muscles. The objective evaluation of meat tenderness is to measure cutting force, penetration, bite force, splitting force, compression force, elasticity and tension with the help of instruments. The most common cutting force is also called shear force, that is, the force required to cut a certain thickness of meat with a blunt knife, in kilograms. Because there are many factors affecting the tenderness of meat, the determination procedure must be standardized so that the results can be compared. Such as sampling time, sampling position, heating mode and sample size.
(3) Water retention: refers to the ability of meat to retain original moisture and replenish moisture. The measurement methods of muscle hydraulic power can be divided into three categories: without any external force, such as dripping method; Applying external force, pressure method and centrifugation method; Apply heat, for example, to reflect the loss of cooking water with cooked meat rate.
(4)pH value: It is an important index to reflect the glycolysis speed of pig muscle glycogen after slaughter. Directly measure the puncture hole of the longissimus dorsi muscle at the penultimate third and fourth thoracic vertebrae of the carcass, or take a piece of meat from a designated part, the width and thickness of which should be greater than 3.0cm, and directly insert the electrode of the pH meter into the puncture hole in the middle of the longissimus dorsi muscle at the designated part of the carcass. If it is inserted into the stripped meat sample, the depth should be not less than 65438±0cm, and the electrode tip should be completely embedded in the meat sample. Read the value of pH 1 (accurate to 0.0 1). When the meat sample is stored in the refrigerator at 0 ~-4℃ for 24 hours, the pH value can be measured. The normal value of pH 1 ranges from 6.0 to 6.6. If pH 1 < 5.9, accompanied by dark meat color and a large amount of exudation juice, it can be judged as PSE meat. The lower limit of pH 1 normal value of individual stress-sensitive breeds (such as Pitland, Belgium, Landrace, etc.) can be set at 5.9. The normal value of pH24 is 5.5. When pH is ph24 >:6.0, it is accompanied by deep purple flesh color and dry muscle surface, which can be judged as DFD meat.
(5) Intramuscular fat (IMF): refers to the fat contained in muscle tissue, which is the amount of fat extracted by chemical analysis, rather than the intramuscular fat that is usually visible to the naked eye. In subjective taste evaluation, rich in intramuscular fat has a good effect on taste comfort, juiciness, tenderness and taste. The optimum content of IMF is 2.5% ~ 3.0%. There are three main methods to determine intramuscular fat content: the first method is Soxhlet extraction (dry sample), which uses ether to extract intramuscular fat; The second is methanol-chloroform method (fresh sample); The third is the marble score of eye muscles.