Preparation Of Cat Food Palatability Enhancer With Enzymolysis Products From Grass Carp Offal

Grass carp is one of the four famous fish of fresh water breeding with a large production,which is rich in nutrition and high protein content,but its edible value is low,and the utilization rate of offal is not so high.With grass carp offal as raw materials,the conditions of its hydrolysis and Maillard reaction were studiedto prepare a cat food palatability enhancer,which will provide a theoretical basis for the deep processing and high value using of grass carp offal.(1)Grass carp offal was used as raw materials,hydrolyzed fish head offal through the compound protease(trypsin and flavourzyme),and optimized protein hydrolysis process of grass carp from response surface experiments.The results showed that trypsin and flavourzyme could significantly improve the amino nitrogen in the Protein hydrolysate from grass carp offal among the papain,trypsin,flavourzyme,neutral protease and alkaline protease,and when the ratio of trypsin and flavourzyme were 3:1,amino nitrogen can reach 11.32mg/g which in the Protein hydrolysate from grass carp offal,significantly higher than the other treatment groups(p<0.05).The results of the single factor experiment showed that when the optimum range of hydrolysis temperature,pH,liquid-solid ratio,composite enzyme dosage were 45-55?,7.0-8.0,3:1-5:1,1.5%?2.5%,there were more amino nitrogen in the Protein hydrolysate from grass carp offal,and when the temperature was 50,pH was 7.3,the ratio of water to material was 4.2:1,enzyme dosage was 2.2%,amino nitrogen product was 12.03 ± 0.11 mg/g.Hydrolysate obtained under this condition contained 17 kinds of amino acids,variety complete,but the content of cysteine which was the intermediate to synthetise meat flavor compounds was relatively low,only 110.6?198.0ug/mL,since we need to add the appropriate amount of cysteine hydrochloride in the subsequent Maillard reaction.(2)In the protein hydrolysate from grass carp offal,glucose and cysteine hydrochloride were used as substrate,reaction condition were pH,reaction temperature,reaction time,through Maillard reaction system to preparation of cat food attractant,and study its ability of antioxidant.The results showed that after enzymolysis of the protein hydrolysate from grass carp offal 4h,preparation of cat food attractant by Maillard reaction with 4%glucose addition,adding 1.5%cysteine hydrochloride as the substrate,when reaction conditions were pH 7,reaction temperature was 115?,reaction time was 40min,have great meat flavor and good baking taste,and sulfur odor of the homemade attractant is significantly lower than the other treatment groups(p<0.05).In addition,Maillard reaction which used glucose and cysteine hydrochloride as substrate can significantly(p<0.05)increase the antioxidant activity of protein hydrolysate from grass carp offal,which performance as scavenging capacity of homemade attractant on-OH free radical,DPPH free radical were 15.12%and 43.41%,chelating ability of Fe2+was also increased to 19.36%.But this kind of self-made attractant had no significant scavenging on 02-(p>0.05).(3)Analysis of self-made attractant and commercial attractant volatile flavor components by GC-MS,showed that there were 64 kinds of flavor in homemade attractants,commercially available attractant has 94 kinds,respectively,hydrocarbons,alcohols,aldehydes and keto acids,esters and other compounds.Both homemade and commercial attractant have obvious characteristics of flavor substances,but flavor groups are different.The specific performance were that in self-made attractant,alcohols and aldehydes were 34.29%,33.52%which were the most relative content of flavor substances;followed by 9.81%keto acids;while in commercially available attractant,hydro carbons and esters are the most relative content of the flavor substances,respectively 23.30%and 28.58%,followed by alcohols and aldehydes.(4)The blank cat food as the carrier,3%homemade attractant or commercially available attractant were added respectively to preparation of cat food,study the acceptance and palatability situation on pet cat for two kinds of food.The results showed that the homemade attractant(75.37%)and commercially available attractant(80.07%)can both improve the blank food intake rate(37.36%),and had no significant difference(p>0.05)intake rate between commercially available attractant and homemade attractant,palatability experiment results showed that the homemade cat food attractant were significantly lower than that of commercially available attractant(p<0.05)in the three indicators such as first olfactory,first feed and rate of feed.Means homemade attractant can effectively improve the intake rate of blank food,but the effect is lower than the commercially available food attractant.Mainly for self-made attractant was used natural raw material in Maillard reaction processing,without adding other umami ingredients and flavors and fragrances.