| Recently Crocodile are mainly raised for leather production, and there is no product or development of crocodile meat to make a full use of resource, which caused a great waste. In order to achieve sustainable and coordinated development of the crocodile farming industry, research was designed on quality development of Crocodylus siamensis. First part of this study was to give a nutrition evaluation of Crocodylus siamensis muscle. Then microbial transglutaminase (MTGase) was added to improve the gel properties of myofibril aiming to provide a reasonable, effective way to solve the technical problems of gel ability of Crocodylus siamensis. Finally, Crocodylus siamensis sausage was developed. The main results were as follows:1) Nutrition evaluation of Crocodylus siamensis muscleCrocodylus siamensis meat was proved to be a good resource of low fat and high protein, with the moisture content77.45%, crude protein77.45%, crude fat2.04%, and ash content0.98%. Sulfur amino acid (methionine and cysteine) is the first restrictive amino acid, while valine is the second one. The ratio of essential amino acid content to non-essential amino acid (EAA/NEAA) can reach up to70.91%, which is higher than meat in common diet, such as pork, chicken, etc. The highest content of five kinds of amino acid in Crocodylus siamensis muscle is Glutamic acid, Lysine, Threonine, Leucine and Histidine from high to low in turn. Crocodylus siamensis muscle contains22kinds of fatty acid mainly. Six of them are saturated fatty acid (SFA), accounted for37.02%; the left16kinds are unsaturated fatty acid (UFA), accounted for63.98%. Compared to the daily edible meat, the content of polyunsaturated fatty acids (PUFA) in Crocodylus siamensis muscle is significantly higher. Linoleic acid and arachidonic acid are the main species of ω6-fatty acid in those polyunsaturated fatty acids, while DHA (C22:6ω3), linolenic acid (C18:3ω3) and EPA (C20:5ω3) are the main species of ω3-fatty acid, with contents of2.96%,2.56%and1.44%respectively. It is found that the ratio of ω3-fatty acid content to ω6can reach as high as44.17%, closer to that in the paleolithic society, which displayed a great medical nutritional value and edible value. It once again proved Crocodylus siamensis muscle as a valuable meat resource.2) Research on gelling properties of Crocodylus siamensis myofibril induced by microbial transglutaminaseThe purpose of this research was to evaluate the effect of MTGase (microbial transglutaminase) on gel properties of Crocodylus siamensis myofibril. Incubation temperature, time and enzyme concentration were studied. The results indicated that MTGase played an essential role in developing gel strength and water hold capacity of Crocodylus siamensis myofibril. Sodium dodecyl sulfate polyacrylamide gel electrophoretic (SDS-PAGE) study revealed that myosin heavy chain (MHC) underwent polymerization to a higher extent in the presence of MTGase. Based on the single factor experiment, the effect of incubation temperature, time and concentration of MTGase were studied respectively as well as their interaction by response surface analysis, taking gel strength and water hold capacity as the response value. The results showed that the optimum condition for strengthening the gelling properties of Crocodylus siamensis myofibril is37.99℃of temperature,2.29hours and0.8U·g-1of MTGase concentration. Under these optimum conditions, the gel strength is509.89g·cm, the water hold capacity is88.09%, respectively2.32times and20.6%higher than gels without MTGase. The results demonstrated that the optimized technology was feasible, and MTGase played an important role in developing the gelling property of Crocodylus siamensis myofibril.3) The development of Crocodylus siamensis sausage productAccording to the characteristics of the Crocodylus siamensis sausage process, the effect of production process recipe to the sausage quality was investigated by single factor test. Considering the indicators of texture (including hardness, springiness, resilience, cohesiveness and chewiness), whiteness, water hold capacity and sensory, the best conditions of single factor test were drawn by comprehensive assessment of the sausages quality.As a result, the quality of the Crocodylus siamensis sausage was significantly improved by the two-stage heating (40℃incubation) compared to the direct heating method.The optimal water addition was proved to be15%. The right amount of salt, starch, sodium pyrophosphate played a catalytic role to the quality of sausages, while too much addition would lead to a decline in quality. For example, the high starch content would lead the product silty easily and decreased elasticity to be easily-broken. Besides, Xanthan gum showed its negative effects to the sausages quality.On the basis of the single factor, the orthogonal experiment was carried out to optimize the sausage production process. The results showed that the amount of salt-addition had an maximum impact on the the indicators of hardness, resilience, chewiness and whiteness, and water hold capacity. Starch had a great impact on cohesiveness and sodium pyrophosphate had a great impact on springiness. The best quality of the sausages were produced after optimization, on the condition of3%salt,10%starch and0.3%sodium pyrophosphate. Finally, MTGase was added in siamese crocodile sausages and proved to achive a better quality of Crocodylus siamensis sausage in real production. |
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