Study On Changes Of Quality And Texture Of Cooked Rice And Its Digestibility Evaluation

Rice,as one of the most important food crops in the world,is also the main source of energy for people in most parts of our country.Nowadays,all kinds of rice food are valued and favored by the majority of people.Exploring the processing characteristics of rice and delaying the decline of rice edible quality have become a hot topic in recent years.Rice starch is the main component of rice,and the process of gelatinization and retrogradation is an important step in the production process of rice food.The cooking texture characteristics of rice are considered to be an important part of the edible quality of rice.The main storage method of medium rice.In this paper,a specific variety of rice is selected.Firstly,the basic components of rice are determined.The cooking method adopts the cooking process of refined cooking in the electric rice cooker commonly used in the market.The rice is cooked under the condition of fixed rice water ratio of 1:4.Using texture analyzer,differential scanning calorimeter(DSC),scanning electron microscope(SEM),Fourier infrared spectrometer and dynamic rheometer,combined with sensory evaluation and cooking quality analysis,the texture characteristics,physical and chemical properties,secondary structure,grain surface morphology,cooking quality and sensory quality of cooked rice in different cooking times were measured and characterized,and simulated in vitro digestion experiments were carried out,The digestion characteristics of cooked rice under different storage conditions were studied and analyzed.The results show that under the condition of fixed rice water ratio of1:4,the best water absorption and expansion rate can be obtained by cooking rice in intelligent rice cooker for 40 minutes.In terms of texture characteristics,cooked rice with different cooking time also shows great differences.With the complete gelatinization of rice,the lowest hardness,adhesion and chewing are obtained,and the texture performance in elasticity and recovery is the best.In terms of sensory evaluation,the score of cooked rice obtained by cooking for 40 minutes in the fine cooking process is 91.68,indicating that the cooked rice prepared by the fine cooking process is more loved and favored by consumers in terms of taste.The results of infrared spectrum analysis showed that there was no formation of new substances in the cooking process of rice.At the same time,the crystallinity of rice starch decreased in a short range,and the molecular order decreased continuously under the promotion of water.Scanning electron microscopy showed that the morphological changes of the surface of cooked rice were caused by the rough and rugged surface structure and the relatively uniform network structure of pores in the cooking process.In the process of rice cooking and gelatinization,the elastic modulus and loss factor Tan of cooked rice are shown by rheological viscoelastic curve δ The increase indicates that rice starch swells with water absorption,and amylose and amylopectin are continuously precipitated during gelatinization.The analysis of thermodynamic characteristics showed that during the gelatinization process of cooked rice,the peak temperature increased and the heat content decreased,which confirmed the gelatinization of rice starch.Finally,the in vitro digestion experiment of rice with different storage conditions after cooking was carried out to determine the digestion characteristics of cooked rice.The measured GI value of rice is 87.23,which is a high GI value food,indicating that cooked rice can be quickly digested and absorbed by the human body after eating,and the blood glucose level rises rapidly.Under the storage condition of-4℃ for 20 minutes,the cooked rice has the lowest GI value and the most nutritional fragments of chronic digested starch and resistant starch.It shows that the low temperature condition can effectively slow down the digestion of cooked rice in the gastrointestinal tract,affect the absorption of glucose,and slow down the rising rate of human blood glucose.It shows that the molecules of rice starch tend to change from disorder to order under the low temperature condition,It further shows that the low temperature condition of-4 ℃ will be conducive to the retrogradation of rice starch.This paper explains the changes in the structure,properties and quality of rice through the cooking process of rice,and has a guiding role in the related processing technology of rice products and starch-based foods.