Study On Development Of Restructured Pomfret Products And Its Quality Characteristics

Pomfret is nourishing, rich in protein, unsaturated fatty acid and kinds of trace elements, it has the pharmacology functions of nourishing stomach, replenishing qi and blood and so on at the same time, it is a economic fish in coastal areas with high production. Recently, due to the low commodity value, the price of many small pomfret caught is cheap, some of them even were abandoned directly, causing a tremendous waste of resources. Restructured fish products have always been an indispensable traditional food for Chinese residents, fish flesh restructuring technique changes the original natural structure of fish flesh, making its muscular tissue, adipose tissue and connective tissue distribute and transform reasonably, it helps to enhance the nutritive value of fish flesh. Therefore, with the adoption of technological conditions in low temperature for shorter time and taking pomfret as raw material, the restructured fish products which are convenient to eat without bone and spur have a great significance to improving the added value of pomfret to provide new aquatic products with high nutritive value and good quality for the market.This issue firstly optimizes the process condition of restructured products by the study of the effect of cooperation of TG, NaCl and SC on the gel strength of restructured pomfret products; then analyses the gel strength, texture, microstructure, protein molecules changes, in vitro digestibility of proteome, water holding capacity and other quality characteristics of restructured fish flesh products made on the optimum conditions, and compare them to the quality characteristics of blank fish sample, restructured products added with TG, restructured products added with TG+NaCl, restructured products added with TG+SC, and then also discusses the functional mechanisms of TG in restructured pomfret flesh products; analyses the nutrition elements of restructured pomfret fish flesh products, building the corresponding nutrition labeling; finally analyses the flavor components in restructured pomfret flesh products, and determines its main taste component and volatile component. The main results are as follows:(1)Taking fresh pomfret as raw material and gel strength as index, under low(5℃) temperature, the optimize process of restructured pomfret flesh products determined by the preliminary selection of single factor experiment condition and response surface analysis are:NaCl 1.47%, SC 1.06%, TG 0.54%, the optimum action time is 2 hours. The function expression of effect of experimental factor got from response surface analysis on response value is as follows:Y=-6635.428+5917.9083X1+1671.3102X2+12722X3-2264.0521X12+261.2917X2X1-1104.9676X22+847.625X3X1+ 549.5833X3X2-13566X32(2) Compared the restructured pomfret flesh products which are made under optimal process condition with restructured products which are only added with one or two materials, we can know that:the gelatin quality, texture property and water holding capacity of restructured flesh products which are made of optimal reaction conditions are superior to other products, while there is no much changes in the digestibility of protein for each sample, they are all about 85%. From the pictures of ESEM we can see that, the structure of restructured pomfret flesh products which are made under optimal process condition is close and dense, the analysis of the microstructure of each recombining product show that TG is a kind of effective binder and elasticity intensifier.The analysis of SDS-PAGE gel electrophoretogram indicate that the main acting protein of TG is myosin of which relative molecular mass is 200KD, the enzyme can catalyze the intermolecular cross linkage or intramolecular cross linkage of protein, making the product structure become more closer, so as to make the restructured fish flesh products can not disperse again even be frozen, sliced, or cooked after shaping, and the protein molecules after crosslinking make the restructured fish flesh products much more flexible.(3) The analysis results of the trophic components of restructured pomfret flesh products are as follow:moisture content is 73.59%, crude protein content is 19.08%, crude fat content is 2.85%, ash content is 2.79%, total carbohydrate is 1.69%. The counterbalance effect of amino acid is good, belongs to the high quality protein; the content of unsaturated fatty acid in fatty acid is 58.07%, of which DHA and EPA account for 10.69%, cholesterol content is 0.13mg/g; total dietary fibre accounts for 0.76%, the total energy 4.59KJ/g; be rich in Ca, Mg, Zn, Se, Mn and other minerals, can be used as the good source of trace elements Zn, Se. According to the related provisions of national standard, restructured pomfret flesh products are high-protein, low fat and low cholesterol food. Taking labelling rules of nutrient composition content in nutrition labeling issued by America FDA as standard, this study builds the nutrition labeling of restructured pomfret flesh products.(4) Study the flavour of restructured pomfret flesh products, analyse the components and contents of organic acid in flavor components and nucleic acid related compounds of restructured fish flesh products, the experiment results show:in organic acid, the highest content is succinic acid (9.56mg/g), then is acetic acid (4.53mg/g), furthermore, citric acid, lactic acid, tartaric acid also be detected. The nucleic acid related compounds are mainly inosinic acid (24.70mg/100g) and sarcine (16.70mg/100g). Using the method of HS-SPME-GC-MS to analyse the volatile components in restructured fish flesh products, the results show that:a total of 36 kinds of volatile components are identified in restructured pomfret fish flesh products, of which the relative content of nonanal is the highest, then is 1-octen-3-octanol, hexana,2-nonanone, heptaldehyde and so on.