| Potatoes are high-yield,economically efficient,rich in vitamins,minerals and dietary fiber that make them important vegetables and crops worldwide.In 2015,China officially launched the strategy of“potato as a staple food”,which transformed the potato from traditional fresh food into staple foods such as noodles,steamed breads that can be produced massively and in line with the eating habits of the Chinese people.Hot dry noodles are traditional specialty snacks of Wuhan,ranking among the top ten noodles in China.The addition of fresh potatoes in traditional wheat flour to make non-fried instant potato hot dry noodles?IPN?promotes the development of potato as staple food grain in China.However,the lack of gluten in the potatoes result in a series of problems such as poor dough strength,high cooking loss,and muddy soup in the process of noodle making and cooking.In this paper,the IPN were taken as the research object,and the effects of three different proteins on their quality characteristics and micro-structure were explored;the optimal ratio of raw materials for making IPN was determined by using the Box-Behnken response surface design;the effects of compound modifiers on the macroscopic quality characteristics and micro-structure of IPN were studied.The optimal drying dynamics model of combined microwave and hot-air drying was established by regression analysis and equation fitting,and the dynamic relationship between the drying method and the comprehensive quality of IPN was explored.The main research contents and results are as follows:?1?The effects of egg white protein?EWP?,soy protein isolate?SPI?and whey protein isolate?WPI?on pasting properties,rheology,water distribution,micro-structure,cooking qualities and texture characteristics of IPN were investigated.The results of RVA and rheological properties showed that all three proteins increased the pasting temperatures,reduced the breakdown of the compound powder,and increased the storage modulus G'and loss modulus G"of the dough.Compared to SPI and WPI,EWP significantly improved the peak viscosity and final viscosity,and had a more remarkable impact on increasing G'values of the dough.The low field nuclear magnetic and SEM results showed that EWP promoted the conversion of adsorbed water to bound water in the dough and the compactness and continuity of the gluten network structure was increased by the addition of EWP.After adding three proteins,the cooking loss of IPN reduced,the hardness,chewiness,tensile strength and cutting textural qualities increased significantly?P<0.05?,as well as the water absorption.Among them,the addition of 2%EWP decreased the cooking loss of IPN,improved water absorption and textural characteristics to the maximum extent.In conclusion,the findings in this work provided evidence that addition of 2%EWP could be the best in the improvement of edible quality in the production of IPN.?2?The formulation process of potato hot dry noodles were optimized by the Box-Behnken response surface.The rehydration time,optical density of iodine?IoD?,cooking qualities,texture and color characteristics of IPN were investigated with the addition of potato puree,modified starch?cassava acetylated distarch phosphate?and egg white protein.In addition to this,multiple target evaluation hierarchy of IPN was constructed by undimensionalization and principal component analysis..Through the comprehensive evaluation system and the multiple linear regression model prediction analysis,the response values were optimized in accordance with all expectations,and the optimum additive amount?%,count as flour weight?were 36%mashed potato,9.8%modified starch and 1.9%egg white powder.?3?Based on the above comprehensive evaluation system,the effects of diacetyl tartaric acid monoglyceride?DATEM?,sodium stearoyl lactate?SSL?and sucrose ester?SE?on the cooking qualities,texture and color characteristics of IPN were investigated.It was found that SSL had the best effect on improving the quality of IPN.The effect of SSL,konjac glucomannan and compound phosphate was evaluated by orthogonal test and the formulation was optimized with comprehensive value as the index.The results showed that the best formula of compound quality improvers was as follow:0.2%SSL,0.4%konjac glucomannan and 0.1%complex phosphate.?4?The drying characteristics and optimal drying process of IPN under microwave combined with hot air drying were explored.The results showed that the microwave-hot air combined drying of IPN occurred in the slow-drying stage;the four commonly used thin-layer drying models were used to perform the regression analysis and model fitting.It was found that the Logarithmic model and the Page model can effectively predict the water dynamic changes of IPN in the microwave drying stage and the hot air drying stage,respectively;the effective water diffusion coefficients of the microwave drying and hot air drying stages of the potato hot dry surface calculated by the gram diffusion equation were 1.90×10-76.33×10-77 and4.93×10-81.65×10-7,respectively.The orthogonalization of microwave-hot air combined drying process was carried out with the rehydration time and comprehensive evaluation value of potato hot dry noodles to determine the microwave surface of potato hot dry surface.The optimum process parameters for hot air combined drying were:microwave drying power 720W,microwave drying time 5min,hot air drying temperature 100°C.Under this drying conditions,the specific expression of the best model equation was:Logarithmic model MR=1.2454exp?-0.20372t?-0.23721 in the previous microwave drying stage;Page model MR=exp(-0.03913t1.22221)in the late hot air drying stage. |
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