| Starch noodle using starch as the main raw material is filaments or strips starch products. So the nutrition composition of starch noodle is lower. Sweet starch noodle is a kind of tradition food production from starches and sale by made into dry products in China. As the economic development and the accelerated pace of life, greater demands are being placed on the convenience and nutrition of starch products. This paper mainly studies that the effect of the addition of spinach juice and the means of low-temperature sterilization on the quality of starch noodle. The experimental results are as follows:Inactivate of enzyme of spinach and squeeze it. The sweet potato starch noodle added spinach juice was investigated by quality indexes such as swelling degree, cooking loss, breaking rate, color, sensory evaluation and so on. The results showed that the spinach blanched in 90℃ water for 80 s have low enzyme activity. The swelling degree, the springiness and the cohesiveness of spinach noodle was reduced significantly when compared with the noodle added free spinach juice; the cooking loss and breaking rate of spinach noodle was increased significantly due to the addition of spinach juice. However, the shear strength and the shear increase first and then decreases with the increase of spinach juice. The L* and a* values of spinach noodle revealed a gradual reduction, the b* and c* value exhibited a gradual increase. The spinach noodle with 25% spinach juice had good acceptability after considering above indexes.The optimum range of each color protecting agent was determined by single factor experiment, with ascorbic acid, sodium carbonate, sodium hydrogen sulfite and calcium chloride as color protecting agent. The response surface analysis was completed through single factor experiment with color as the response value. The optimal preparation conditions of color protecting agent were as follows:ascorbic acid 0.13%, sodium carbonate 0.03%, sodium hydrogen sulfite 0.07%, calcium chloride 0.08%. The experimental value of △a* and △E* was 0.6899 and 1.1591 which was well consistent with the predicted value of 0.702 and 1.146. Prediction accuracy was as high as 98%, therefore the optimal results were reliable.Microbial growth and reproduction is a major cause of spoilage of fresh wet starch noodle. Sterilization of the vacuum packed fresh wet starch noodle can reduce the quantity of bacteria in order to achieve preservation and prolong the shelf life. By the single factor to determine the most conditions as follows: packaging quality 250~300 g, microwave time 4~6 min, microwave power 420~700 w. The orthogonal basis on single factor showed that the optimal sterilization procedure parameters ware as follows: the package quality 250 g, microwave time 6min, microwave power 700 w. Comparison of combination of pasteurization and microwave sterilization and pasteurization with unpasteurized on qualities of starch noodle, results show that combination of pasteurization and microwave sterilization have a greatest influence on the qualities of starch noodle, but little effect on the senses.The influences of ozone sterilization, the combination of pasteurization and microwave sterilization and the pasteurization on starch noodle in storage were investigated. According to factor analysis, scores of the cooked mutton which is sterilized by different ways and stored in different time were given. The results showed that the first principal component mainly represents the changes of △a*, △E*, pH, total plate count; the second principal component mainly represents the changes of the boil loss, swelling degree, shear strength, cohesiveness. The first principal component and the second principal components can explain products overall quality difference of 87.945%(> 80%). So the quality of the starch noodle can be evaluated by two overall indicators in storage. The quality of starch noodle reduced during storage, combination of pasteurization and microwave has the best quality of the same storage time. |
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