Effects Of Different Treatment Of Temperature And Addition On Functional Properties Of Porcine Myofibrillar Proteins

Myofibrillar proteins(MP) accounts for 50%～55% of the total proteins in muscles, which were consisted of myosin, actin, tropomyosin and troponin and so on. The heat-induced gel of muscle proteins is crucial to many meat products, so, it's meaningful to invest into the changes of myofibrillar proteins during heating treatment.Pork longissimus dorsi was sampled to study the effects of temperature, heating time, and the addition of glucono-δ-lactone(GDL) and egg white proteins(EWP)on characteristics of heat-induced gel of myofribrillar proteins. The main results were stated as follows:1.The functional properties of MP were invested through heating from 50℃to 90℃.The results showed that, the gels prepared from 70℃to 80℃have a better water holding capacity (WHC) compared with other treatments; The gels had a deeper color when heated from 50℃to 60℃,when other treatments deserved a similar color(P>0.05); The hardness and chewiness rose at the beginning and decreased when temperatures increased; The best consequence was obtained at 70℃～80℃;The emulsion ability index(EAI) went to the peak at 70℃,emulsion stability index(ESI) was not affected significantly by temperatures(P>0.05).2. Three of the heating time(10min,20min and 30min after the central temperature reached the desired temperature) were designed to invest the functional properties of MP.The results showed that, heating of 30min had the best WHC, and the whiteness went to the minimum at the same condition. Different heating time had no significant effects on springiness of the gel (P>0.05); When 0.5%,1.0% and 1.5% of the GDL were added, the cohesiveness was significant higher(P<0.05).3.The functional properties of MP affected by the addition of GDL(0.5%,1.0%,1.5% and 2.0%, w/w) were investigated. Results showed that, The WHC was improved when 1.5%-2.0% of GDL was added; The hardness was the highest at 80℃and GDL was 1.5%(P<0.05), the chewiness hit the peak at 80℃～90℃and GDL was 2.0%. Adhesiveness and whiteness decreased with the increasing of GDL. The emulsion of the myofibrillar proteins added with GDL wss significant higher than contrast(P<0.05), but the mount of GDL make no difference(P>0.05). It was the highest at 70℃compared to that of other temperatures. The result was also improved by the scanning electron microscope, which showed that the texture of the gel becoming more compact when the GDL increased.4. The effects of different addition of egg white protein(EWP) on MP was investigated. The results showed that, WHC, hardness, cohesiveness, springiness and resiliency of gels had a downward trends when the addition of EWP increased. The whiteness of gel was not affected by EWP(P>0.05). EAI was also not affected by EWP, but ESI decreased when EWP was added(P<0.05).