Inlfuence Of Frozen, Freeze-thawing And Carcass Weight On Meat Quality And Muscle Framework Of Organization Of PSE Meat

The influence of frozen storage time and repeated freeze-thawing on meat quality and framework oforganization of PSE pork with different carcass weight were investigated in this paper. The investigationwere conducted by exploring variation and reason of the difference of PSE pork with different carcassweight from the perspective of several characteristics of water-retention property, tenderness, proteincontent and muscle tissue fibroblast. The paper include the following three parts:1) Compare of quality andmuscle tissue fibroblast between mild PSE pork and normal pork.2) The influence of frozen storage timeon muscle tissue fibroblast of mild PSE pork and normal pork.3) The influence of repeated freeze-thawingon the quality of PSE pork and normal pork.1Compare of quality and muscle tissue fibroblast between mild PSE pork and normal pork.The main purpose of this article is to study the distinguish characteristics of meat quality and musclefibers diameter and density between mild PSE meat and normal pig in high temperature rearingenvironment. With the increase of carcass weight that range from80to85kg, shear force and spring ofnormal meat increased significantly (P<0.05), total moisture decline significantly (P<0.05). Whereas,intramuscular fat content of mild PSE meat decline significantly (P<0.05), dehydration rate and shear forcehad an increasing tendency (P>0.05), total moisture had decline tendency (P>0.05). While, dehydrationrate, total moisture and sheer force of mild PSE meat increase significantly (P<0.05), protein content haveno obvious change (P>0.05). The mild PSE meat intramuscular fat and spring about85kg carcass weightdeclined significantly than normal meat (P<0.05). The same carcass weight, muscle fibers diameter onbiceps femoris muscle of mild PSE meat is significantly lower than normal meat (P<0.01), its musclefibers density is significantly higher than normal meat (P<0.01).The mild PSE meat pig intramuscular fathigh temperature rearing on same weight range from80to85kg lower than normal pig, whereas, shearforce and dehydration rate were high. The quality of PSE meat pig with85kg are worse than the quality ofmeat pig with80kg, the quality of normal meat pig also have a good quality.On the organizational structureof muscle fiber, mucle fibers of mild PSE meat has obvious shrinkage, mucle fibers of normal pork don’thappen2Freezing storage time on normal mild PSE pork and meat quality and the influence of the muscle tissuestructureWith mild PSE pork and normal pork as the research object,at-18℃frozen for3weeks,6weeks,9weeks,12weeks,15weeks,18weeks,meat quality and muscle tissue structure are measured andobserved.The study found along with the frozen storage time prolonging, pork pH value decreased first andthen increased, the acidity-oxidizing ability coefficient measurement increased firstly and then decreased,thawing loss, TVB-N, microbiology counts and shear force gradually increased, the protein contentdecreased. Compared with the normal meat, mild PSE pH values of amplitude is not obvious, microbiologycounts and TVB-N increased quickly, at18weeks, mild PSE pork longissimus muscle reached level twofresh meat, normal for a fresh degree.Frozen before9weeks, the protein content of mild PSE meat wassignificantly decreased (P<0.05). Frozen for12weeks, normal pork decreased significantly(P<0.05),Frozen in mild PSE, shear stress was higher than that of the normal meat.Thawing loss of mild PSE werehigher than normal pork meat. In the frozen for3weeks and18weeks, thawing loss stock two myo-than the longissimus muscle force and the colony total low, the ratio of shear longissimus dorsi high,volatilebasic nitrogen content than low the longest back muscle.Of the biceps femoris muscle in muscle tissuestructure along with the increase of freezing storage time, there is an obvious chaos pork muscle fiberstructure, the clearance between the muscle fiber increases gradually, the occurrence of mild PSE meatchanges than normal meat more obvious.Results show that: in3-18weeks frozen storage, organizationstructureof mild PSE and normal pork muscle damage,compared with the normal meat, mild PSE meatmucle tissue structure change is more apparent, faster decline in mild PSE meat quality.Look from differentparts, the test of the biceps femoris muscle in his volatile base nitrogen slow growth, the water is strong,back muscle protein content is high, the longest tenderness.3The influence of repeated freeze-thawing on the quality of PSE pork and normal pork.In order to investigate the influence of repeated freeze-thawing on meat quality, this experiment wasconducted on the mild PSE pork and normal pork repeated freeze-thawing six time under the condition of-18℃, then meat quality were determined. The results are as follow: Accompany with the decrease ofrepeated freeze-thawing time, TVB-N, unfreezing loss and elastic properties of mild PSE pork and normalpork were all decrease significantly, acidity of oxidizing power presented increasing trend firstly and thendecreased, PH value and VBN decreased firstly and increased secondly, shear force and the content ofprotein also had significantly change. The mild PSE pork with one and two freeze-thawing time hadsignificant lower content of protein than normal pork (P<0.05). The mild PSE pork with twofreeze-thawing time had significant lower unfreezing loss than normal pork (P<0.05). Simultaneously, pHvalue of mild PSE pork with two freeze-thawing time were significant lower than normal pork. Comparingwith normal pork, the mild PSE pork with three freeze-thawing time had higher acidity of oxidizing power（P<0.05）. Shear force of mild PSE pork with one, two and six freeze-thawing time were more high thannormal pork（P<0.05）. With the increase of repeated freeze-thawing time, TVB-N of mild PSE pork hadfaster increasing rate than normal pork. Elastic properties of mild PSE pork with six freeze-thawing timesignificantly lower than normal pork（P<0.05）. The experiment and the determination result above indicatethat the quality of mild PSE and normal pork with repeated freeze-thawing have degradation trend, duringwhich, the freshness, elastic properties and tenderness degraded significantly.