Study On The Corruption Of Fresh Chicken And Biological Preservatives

That the chicken will spoilage during the storage and the limited shelf life is one ofthe main obstacles that hinder the further development of chilled chicken. The chilledchicken was used as experimental materials, and the changing rule of fresh degreeindexes (TVB-N examination, pH measurement, TBA measurement, total bacteria counts)of different parts of fresh chilled chicken with decaying during storage were studied. AndTPA (Texture Profile Analysis) was applied for the determination of fresh chilled chickenleg, and hardness, springiness, chewiness and cohesiveness changing with time wereanalyzed by regress analysis. Then the fresh-keeping effect of chitosan derivatives ofdifferent concentrations on the fresh chilled chicken was researched. A series of centralcomposite design experiments was conducted for developing a mathematical regressionmodel for TVB-N values as a response of three variables (namely carboxymethyl chitosa-n, Nisin and lysozyme), providing thoery base for extending the shelf life of chilledchicken. Main contents and conclusions are as follows:1. The changing rule of fresh degree indexes (TVB-N examination, pH measure-ment, TBA measurement, total bacteria counts) of different parts of fresh chilled chickenwith decaying during storage were studied. Pertinence between the indexes was set andthe possibility of chilled chicken fresh degree was determined by regress analysis. Theregression equations of the TVB-N values of chicken leg, chicken back, chicken wingsand chicken breast increasing with time were made respectively: chicken leg y=7.630703+0.175386x-0.001708x~2+0.000007x~3、chicken back y=7.859023-0.249751x+0.014495x~2-0.000238x~3, chicken wings y=7.119564-0.171778x+0.012173x~2-0.000225x~3、chickenbreast y=6.957404-0.140322x+0.009938x~2-0.000173x~3. And the regression equations ofpH measurement and the TVB-N values were also made respectively: chicken leg y=7.486653-0.205354x+0.012958x~2-0.000224x~3、chicken back y=7.859023-0.249751x+0.014495x~2-0.000238x~3、chicken wings y=7.119564-0.171778x+0.012173x~2-0.000225x~3、chic-ken breast y=6.957404-0.140322x+0.009938x~2-0.000173x~3.2. During the cold storage, TPA (Texture Profile Analysis) was applied for the deter-mination of fresh chilled chicken leg, and hardness、springiness、chewiness andcohesiveness changing with time were analyzed by regress analysis. And the regression equations were made respectively: hardnes y=8.582060-0.03225x+0.000149x~2-0.0000005x~3、springiness y=5.682245-0.005645x+0.000020x~2-0.00000008x~3、chewiness y=20.493286-2.229867x+0.060811x~2+6.562141x~3、cohesiveness y=1.062037-0.124230x+0.012970x~2-0.000675x~3, which provided data base for evaluation of chicken quality.3. The antibacterial activity of different kinds of chitosan derivatives wascompared.The fresh-keeping effect of carboxymethyl chitosan of different concentrationson the fresh chilled chicken was researched. The experimental results showed thatcarboxymethyl chitosan had distinct fresh-keeping effect. When the concentration ofcarboxymethyl chitosan was1.5%, the fresh-keeping effect to fresh chilled chicken wasthe best.4. Fresh chicken was treated with carboxymethyl chitosan, Nisin and lysozyme. Aseries of central composite design experiments was conducted for developing a mathemat-ical regression model for TVB-N values as a response of three variables (namely carbox-ymethyl chitosan, Nisin and lysozyme). The results showed that fresh-keeping effect ofcarboxymethyl chitosan was the best, and Nisin was better than lysozyme. There was extremely significant synergy between carboxymethyl chitosan and Nisin, but synergybetween carboxymethyl chitosan and lysozyme was not significant, the same to Nisinand lysozyme. Moreover, when the combination of biological preservatives was1.85%carboxymethyl chitosan,0.05%Nisin and0.08%lysozyme, the fresh-keeping effect onfresh chilled chicken was the best.