Study On The Key Production Process Of Fresh And Wet Instant Rice Noodles And Its Mechanism Of Rice Flour Quality

Fresh and wet instant rice noodles are a kind of rice products made from rice by fermentation(or no fermentation),pulping(pulverization),gelatinization,aging,sterilization and other processes.It can be eaten by boiling in boiling water for 5?10 minutes.Its moisture content ranges from 30%to 60%and Its shelf life is up to 3 months..In the production process of fresh and wet instant rice noodles,the maintenance of rice flour quality(elasticity,toughness)and the prolongation of shelf life are two problems that need to be solved urgently.Based on the previous research of the research group,this paper selects Guichao rice as raw material,and uses the water content of the material as 70%,100 ? and 10min as the initial gelatinization condition.Firstly,the relationship between the fermentation process of raw materials and the toughness of fresh and wet instant rice noodles was discussed.Then the effect of aging process on the quality of rice noodle gel was studied.Then different sterilization methods were used to prolong the shelf life of fresh and wet instant rice noodles.And after the sterilization,the production process of the rice flour in the early stage was optimized and adjusted.Finally,the process conditions of fresh and wet instant rice noodles were determined.At the same time,the mechanism of the production process affecting the quality of fresh and wet instant rice noodles was studied.The relationship between the quality of fresh and wet instant rice noodles and the molecular structure and crystallinity of starch was found out.The factors affecting the quality of fresh and wet instant rice noodles were determined.The specific results were as follows:(1)The physical and chemical properties,texture quality and sensory score of fresh and wet instant rice noodles were used as indexes.The natural fermentation process of rice,the aging process and sterilization process of fresh and wet instant rice noodles were studied.The results showed that:When the acid value of rice is 0.532.T(37?/20h),the aging degree of fresh and wet instant rice noodles is 6.74?7.13,and the quality ofresh and wet instant rice noodles is better:the elasticity increased to 1.3 times,the broken rate decreased to 8.4±1.0,and the sensory score reached 87.0 ±1.4.The germicidal rate of fresh and wet instant rice noodles was above 85.0%after sterilization at 90 C/30 min and microwave 600W/60s,but the physicochemical and texture quality of fresh and wet instant rice noodles decreased significantly after sterilization.(2)After sterilization,the breakage rate and the absorbance value of mixed soup increased by 1.1 times and 0.8 times respectively.This is because the moisture content is too high(51.41%),and the fresh and convenient rice noodles are re-gelatinized during the sterilization process.Therefore,the pre-process of the fresh and wet instant rice noodles has been re-adjusted.The results showed that:Gui Chao rice crushed through 30 mesh sieve(0.600mm)? natural fermentation(The acidity value was 0.532 °T)?drying(40?/7h)?crushing sieve 120 mesh(0.125 mm)?proportional humidity control(moisture content 50%)?Gelatinization(The degree of gelatinization was 85.4%)? Squeeze ? Aging(Aging degree was 6.74-7.13)?Sealed packaging ?Sterilization(90?/30min)?Finished product.Mechanism of the influence of production process on the quality of rice flour:(1)The effects of molecular structure and crystallinity on the quality of rice flour were compared by natural fermentation method,pullulanase degradation of amylopectin and beta amylase to randomly degrade starch.The results showed that:In the natural fermentation process,the macromolecular amylopectin in zone I is first debranched(12h),and then the long chain of amylopectin is broken(16h).Correlation analysis showes that,the DE value of starch,the number average molecular weight of II,the degree of polymerization,and the crystallinity are significantly correlated with the quality of the fresh and wet instant rice noodles.When the DE value of starch reaches 2.88%,the number-average molecular weight of starch in zone II increases to 9.1 X 104g/mol g/mol,the degree of polymerization increases to 7.0 X 103g/mol and the crystallinity reaches 30.30%,the quality of the fresh and wet instant rice noodles is better.(2)The relationship between water distribution state,surface microscopic morphology,starch molecular structure,crystallinity and aging quality of fresh and wet instant rice noodles was discussed.The results showed that:The quality of the fresh and wet instant rice noodles is significantly correlated with moisture retention time T22 and starch crystallinity,and is not correlated with starch molecular weight distribution.When the aging degree of the fresh and wet instant rice noodles is controlled at 6.96,the crystallinity of the fresh and wet instant rice noodles is increased to 30.81,and the water retention time is decreased to 9.83 ms.At this time,the surface structure of the rice flour is smooth and compact,the breaking rate of the fresh and wet instant rice noodles is reduced to 8.4%,the elasticity is increased to 0.88 mm,the chewiness is increased to 37.52 mj.(3)The relationship between heat sterilization,microwave sterilization and the quality of fresh and wet instant rice noodles was discussed.The results showed that:Thermal and microwave sterilization can break the chain of macromolecular starch in zone I.It increases the degree of aggregation of starch in zone ?(21.3%?40.1%).After sterilization by heat and microwave,the surface of the fresh and wet instant rice noodles becomes rough.The crystallinity of rice flour is decreased(7.37%,9.83%),and the broken rate is increased(1.1 times,1.2 times).