Effects Of Lactic Acid Solution Soaking And Microwave Drying On The Quality Of Instant Rice Noodles

In this thesis, early indica rice was used as the raw material. The effects of lacticacid solution soaking and microwave drying on the quality of instant rice noodleswere studied. The research results are as follows:The eating quality and the volatile compounds of instant rice noodles whichwere made of rice soaking in lactic acid solution and water were compared. Theresults indicated that there was a certain improvement in the quality of the instant ricenoodles which were made of lactic acid soaking rice. The sensory evaluation scoreswas higher,the flexibility was better and the hardness of TPA was smaller of lacticacid solution soaking rice produced rice noodles than the water saoking rice producedrice noodles. The DVB/CAR/PDMS SPME fiber was suitable for extracting thevolatile flavor compounds of the rice noodles. And the results showed that there were59volatile compounds of lactic acid solution soaked rice noodles while36volatilecompounds were identified in the the water soaked rice noodles. The lactic acidsolution soaking improved the flavor of instant rice noodles, especially increased thevariety and cotent of hydrocarbons, acids and esters and reduced the content ofalcohols.The drying process of microwave and hot air thin layer drying were studied andthe results indicated that the drying process could be divided into the accelerationperiod, the constant rate period and the falling rate period. Under the chosenexperimental conditions, the constant rate period could be observed only at160w,320w of microwave drying and40℃,60℃of hot air drying. Twelve commonly usedthin layer drying mathematical models were evaluated with the experimental data andthe results indicated that Midilli-Kucuk model and Hii, Law&Cloke model were themost adequate models in describing and predicting moisture transfer of instant ricenoodles during microwave drying and hot air drying. The effective diffusioncoefficients of moisture transfer were1.44×10-9~6.42×10-9m2/s of microwavedrying and1.44×10-9～6.42×10-9m2/s of hot air drying. The quality of instant rice noodles were affected by the drying methods anddrying conditions. The results indicated that480w and80℃were the most adequateconditions for microwave and hot air drying by comparing the rehydrate ability,breaking rate, sensory evalution, slurry rate and TPA characteristic parameters.