Preparation Of Cat Food Palatability Enhancer From Silver Carp Scraps

Low-price aquatic products are mainly obtained from low-valued fish and by-products of aquatic products.Because of their poor taste unsuitable for eating,they are processed into fish meal or directly used as fodder in China.Water area is vast territory,and total freshwater fish are aboundant in our country.However,the process industry falls behind of foreign for the complex procession,and the processing industry of scraps is rare,which not only caused the waste of resources,but also lead to environmental pollution,Therefore,it is urgent to develop the deep process technologies of freshwater fish especially low value fish protein.Silver carp is one of the four famous fish with a large production,which is rich in nutritions and high protein contents,but its edible value is low,and the utilization rate of scraps is also low.In this paper,with the head of silver carp,the most important part of fish byproducts as raw materials,the conditions of its hydrolysis and Maillard reaction were studied to make a cat food palatability enhancer with rich flavour,which also provided a theoretical basis for the deep process and high value using of silver carp scraps.The hydrolysis effects of papain,trypsin,flavourzyme,neutral protease and alkali protease were compared and selected,with the content of amino nitrogen in the hydrolysate as an index.The hydrolysis process was optimized by orthogonal tests on the basis of single factor,and the composition of free amino acid in hydrolysate was analyzed.The results showed that trypsin could be selected as the best hydrolysis enzyme,and the maximal content of amino nitrogen in hydrolysate reached 63.69 mg with the following conditions:hydrolysis temperature of 55?,pH 9.0,the ratio of water to materials 1:3,enzyme concentration 80 u/g,and the content of free amino acid in hydrolysate were higher.The volatile flavor component in commercial cat food and cat food palatability enhancer was extracted by the method of solid phase microextraction and detected by GC-MS to analyze composition and relative content in them.The method of GC-MS could mainly detect 7 types of compounds,including hydrocarbons,aldehydes,ketones,alcohols,esters,acids,and ring compounds,which mainly presents the odour of fat,meat,baking,nuts,mushrooms,cream,and so on.The flavor profile method is used in the sensory evaluation of commercial cat food and palatability enhancer,and the meat odour and roast odour was made for the characteristics flavor which cat food palatability enhancer should have.By the means of sensory evaluation for the Maillard reaction products from the hydrolysate of different digestion time,the optimal hydrolysis time of 4 h was obtained.In this time,the meat odour and baking odour of the reaction product was highest,and the sulfur odour was weaker.On this condition,the maillard reaction process is optimized by the method of brief description and sorting sensory evaluation,and the optimal result was reached with the following conditions:adding 5.0%reducing sugar(glucose:D-xylose=1:1),1.0%L-cysteine hydrochloride,0.5%oryzanin and 1.0%Na2HPO4,adjusting pH to 7,then reacting at 110? for 50min.On this basis,the powder palatability enhancer was obtained by spray drying.Compared with the palatability enhancer before spray drying,its meat odour was weaker,but sulfur odour disappeared.The volatile flavor component of cat food palatability enhancer was also analysised by GC-MS,The results showed that the prepared palatability enhancer included the main flavor component which forming the characteristics flavors.The appkication effect in basic cat food of self-made cat food palatability enhancer was tested by the method of palatability test.The single bowl test result showed that the intake rate of three kind cat food added PEA,PEB and commercial palatability enhancer was 46.34%,72.59%and 76.94%,which were higher than basic cat food 46.34%.we can get following conclusions from the first choice test and the two bowls test result:the first choice amount and consumption ratio of cat food covered with prepared palatability enhancer were much higher than that basic cat food,and the palatability of PEA was slightly higher than PEB.But there was a certain distance between self-made cat food palatability enhancer and commercial palatability enhancer,we can improve it by compounding in the later research.