The Effect Of Buckwheat Trypsin Inhibitor On The Gelling Properties Of Chicken Meat Gel

With the advantages of high nutritional value,diverse product types,convenient and quick consumption,meat emulsion has a broad market prospect.The gelatin properties of the meat emuls ion play an important role on the texture,appearance and yield of the meat emuls ion products.How to improve the gel properties of the meat emulsion is a common focus of the meat processing industry.The endogenous enzyme in the meat raw material is a key factor lead ing to deterioration of the meat emulsion and deterioration of quality.The inhibitor has strong specific ity against enzymes and is convenient in process.Hence,inhibitor is an effective way to inhibit endogenous enzymes in food.The currently-used enzyme inhibitors for food application are mainly small-molecule compounds;however,the study of using enzyme inhibitors with polypeptide or protein in food application is scarce.In this study,buckwheat trypsin inhibitor(BTI)was used as the experimental material and its effect on the properties of chicken meat emuls ion gel was evaluated.This project will form a solid foundation for potential applications of protease inhibitors in food industry and provide scientific basis for developing new additives to improve gel properties of minced meat products.The main contents of this work are as follows:Part one: Induced expression,affinity purification and thermal stability analys is of BTI.Soluble expression of recombinant of BTI was induced by IPTG.Crude protein was obtained by ultrasonically disruption and further purified by Ni2+-column affinity chromatography.SDS-PAGE results showed that BTI with high purity was obtained by only one-step affinity chromatography.BTI exhibited a high inhibitory activity against trypsin.Thermal stability experiments showed that BTI was thermo-stable,with a 70.23% inhibition rate after boiling for 100 min.Part two: The method for preparing chicken meat emuls ion with starch and BTI as additives was built.To evaluate the effect of BTI on the gel quality,gel properties inc luding the whiteness,water retention,cooking loss rate,strength,puncture force and adhesion were measured.The preparation process of the chicken meat emuls ion gel was as follow,the addition amount of starch,salt and BTI was 2%,3% and 0.07‰ of the meat quality,respectively.The result showed that BTI had no significant effect on gel whiteness.However,with the increase of BTI,the water retention of chicken meat emuls ion gel was improved,the cooking loss rate was reduced,and the texture characteristics of chicken meat emuls ion gel(puncture force,adhesion,extrusion,and strength)were significantly improved.The puncture force,squeezing force and strength of the chicken meat gel were s ignificantly improved with an amount of BTI 0.03‰,and the adhesion of the chicken meat gel was significantly improved when the addition amount was 0.05‰。Part three: To explore the mechanism of gel formation and stabilization after adding BTI,the protein content,composition,and chemical forces were studied.The content of TCA-soluble peptide of the chicken meat emuls ion gel decreased after BTI was added.Compared with non-addition group,the content of TCA-soluble peptide of group added with BTI decreased significantly during storage.As determined by SDS-PAGE,the degradation of myosin heavy chain and actin by endogenous enzymes could be inhibited effectively by BTI.The degradation of myosin by endogenous enzymes is a key factor for destroying the gel structure of the meat emuls ion.BTI is an effectively inhibitor against trypsin and decrease the degradation of myosin by endogenous enzymes including trypsin.Therefor BTI enhanced the stability of the gel structure of chicken meat emuls ion gel.Analys is of chemical forces indicated that hydrogen bonding and hydrophobic interaction were the main forces for maintaining the three-dimensional structure of chicken meat emulsion gel.