Study On Characteristics And Properties Of Heat Coagulated Yam And Egg Whole-pulp

Chinese yam,a traditional medicinal and edible “tonics”,is rich in abundant mucin and active polysaccharides.Hense,it possesses a variety of nutrient effects,such as benefiting vital energy,nourishing lung and delaying cell aging,and is honored as the “immortals food”.Especially,"Anshun Yam" from Guizhou with outstanding qualities,was awarded the “Geo-label commodity of Agricultural Products” by the Ministry of Agriculture in 2010.As one of the key industries of mountain livestock farming,the egg industry developed rapidly.However,due to the hysteresis in the development of processing,egg preservation in summer is a problem.Therefore,the purpose of this paper was to develop a new composite yam-egg curd,in which yam and eggs were selected as raw materials by the whole-pulp coagulation hot gel technology.Firstly,the effects of yam slurry dosage,cooking temperature,pressure and time on the texture and cholesterol content of yam-egg curd were studied and then processing parameters were optimized according to hardness and elasticity.Secondly,the flavor,taste,microstructure,moisture state,and sensory quality of different egg curd were compared.Finally,the dynamic changes of the texture characteristics of the composite yam-egg curd were studied under low temperature(4°C)and room temperature storage(24±2°C),and compared with that of pure egg curd.The results showed that:1.The optimum conditions of the egg processing parameters indicated that the influences on elasticity and hardness were in the order: cooking time(C)> cooking temperature(B)> yam slurry dosage(A)> cooking pressure(D).The yam slurry dosage had a remarkable effect on the texture parameters(elasticity)(P<0.05).The yam slurry dosage and cooking temperature had a significant effect on the textureparameters(hardness)(P<0.05).The optimum technological condition combination was A2B2C2D2,in which yam slurry dosage,cooking time,cooking temperature,and cooking pressure were 5%,105 min,100℃ and 0.26 Mpa,respectively.Under the optimum conditions.,the cholesterol content of yam-egg curd was 379 mg/100 g,which was 25.67% lower than that of pure egg curd.2.The product flavor analysis(SPEM-GC-MS)showed that,aldehydes,alcohols,and compounds containing N and S,were the main volatile flavor compounds in egg curd,yam-egg curd and commercial egg curd,accounting for 51.19%-92.02%.However,the contents of alkane and phenolic compounds in compound yam-egg curd were higher than that in egg curd,accounting for 16.78% and 1.32%,respectively.It is noteworthy that the heterocyclic compounds in commercial egg curd was 9 and16 times higher than that in the composite yam-egg curd and egg curd.3.Electronic tongue technique(ETT)was used in the taste analysis,and the results showed that the acidity,bitterness,astringent aftertaste and bitter aftertaste in compound yam-egg curd and Miaoganma egg curd were decreased by 20.20%,21.03%,15.63% and 51.59%,respectively.Whereas the umami and umami richness were both 2 times than that of the original egg curd.However,the bitter taste,astringency aftertaste and the salty taste of commercial pure egg curd declined gradually compared with Miaoganma egg curd,while the astringency increased by14.71%.However,the umami had no obvious change.4.The results of moisture state,amino acid,sensory evaluation and microstructures showed that,immobilized water was the main moisture state,accounting for 87.82%—99.16%.The contents of combined water in Miaoganma egg curd,compound yam-egg curd and commercial egg curd were 1.84%,12.18% and11.22%,respectively.The composition of amino acids had no obvious changes.The highest sensory score was the yam-egg curd,followed by commercial egg curd,and Miaoganma egg curd.The microstructure of yam-egg curd was smaller and denser,which was consistent with sensory evaluation.5.The storage tests showed that the main texture characteristics(hardness,elasticity,chewiness,cohesiveness,adhesion)of the yam-egg curd and Miaoganmaegg curd were all increased with the storage time at room temperature(24±2℃)and lower temperature(4℃).However,the main texture characteristics of both the yam-egg curd and egg curd at 4℃,changed less than that in the other temperature and had a better stability,which was good for quality preservation.