| Potato vermicelli is a traditional food in China and is the most popular in consumers.Because of the low amylose content in potato starch,it?s not easy to form,and easy to break,muddy soup,have a poor taste.At present,alum is mainly added to the market to solve such problems.With the improvement of people's living standard,fast-paced life is becoming more and more prominent.People have more and more strict requirements for the safety and convenience of the vermicelli.This research mainly screens the additives allowed for vermicelli processing in the GB2760-2014 to replace alum processed potato fresh vermicelli,on the one hand,optimizes the production quality of vermicelli in combination with the production process optimization.At the same time,based on achieving alum-free potato fresh vermicelli,further screening preservatives to extend the shelf life of potato fresh vermicelli.The main research results of this paper are as follows:(1)The effects of different additives on the gelatin texture,settling ability,and swelling of potato starch were determined to screen alum substitutes suitable for vermicelli production,and compound optimization was performed by single factor and orthogonal experiments.Studies have shown that the three additives of carrageenan,agar,and sodium alginate are compared with other additives,which similar to the addition of 0.351%alum,they have no significant effect on the swelling degree of potato starch(P>0.05),at the same time,it has the properties of significantly improving the hardness,viscosity and chewiness of potato starch gels and starch settling properties(P<0.05).Through single factor and orthogonal experiments,it was found that the production of potato fresh vermicelli with 0.6%agar,0.4%carrageenan and 0.8%sodium alginate as alum substitutes,the obtained vermicelli's break rate is 0%,the transmittance is 93.20%,the sensory score is 83.75.(2)On the basis of(1),the Box-Behnken experimental design and principal component analysis were used to optimize the processing technology of alum-free potato fresh vermicelli.The results showed that the cumulative contribution rate of the first to the third principal components was 85.408%,which was enough to describe the quality of alum-free potato fresh vermicelli comprehensively reflected by shear strength,tensile strength,elasticity,viscosity,mastication,and sensory score.The quadratic polynomial regression model based on the normalized comprehensive score obtained by principal component analysis as the response value has a significant regression effect and a good fit(P<0.0001,R~2=0.9577).Partial least squares regression analysis predicts that the optimal process formula for alum-free potato fresh vermicelli is 55.3%of water addition,10.5?of cooling temperature,20.5%of additional time,and 50min of cooling time.The theoretical overall score is 0.8975.Under this condition,the normalized comprehensive score of alum-free potato fresh vermicelli was 0.8898,which was close to the model prediction value.The alum-free potato fresh vermicelli produced under this condition had smooth mouthfeel,moderate viscoelasticity,0% of the breaking rate,94.4% of transmittance,and the sensory score is 88.68,the shear strength is 55.79 g/mm~2,the tensile strength is 4.70g/mm~2,the elasticity is 4.53,the viscosity is 348.77,and the chewiness is 1537.29.which can realize the production of potato fresh vermicelli instead of alum.(3)Taking the total number of colony and mold of alum-free potato fresh vermicelli as the index,the additives suitable for fresh-keeping of alum-free potato fresh vermicelli were selected,the compound preservative was optimized by orthogonal experiment,and verify the preservation effect of preservatives with the color difference,p H,sensory,and cooking loss rates of alum-free potato fresh vermicelli were analyzed at 4?,25?and 37?of temperature.The results showed that sodium diacetate,sodium dehydrogenate and citric acid can inhibit the growth of bacteria and molds of alum-free potato fresh vermicelli and meet the sensory requirements of the product.Through the orthogonal experiment,the optimal ratio of preservative is 0.015%of sodium diacetate,0.080%of sodium dehydrogenate and 0.120%of citric acid.After 8 days of storage at 25?,the total number of colonies and the total number of molds in the preservatives group were 1450 CFU/g and40 CFU/g,The difference between the blank group was extremely significant(P<0.01).The verification results show that the preservatives can slow down the changes in color difference,p H,the sensory and cooking loss rate of alum-free potato fresh vermicelli during storage at 4?,25? and 37?,which played a role in preservation. |
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