Effect Of Baking Soda On Cooking Quality And Starch Properties Of Brown Rice

Compared with polished rice,brown rice retains more nutrients such as dietary fiber and vitamins,and has higher nutritional value.However,due to the substances such as dietary fiber,bran wax and phytate in the rice bran layer of brown rice,the brown rice is difficult to cook,poor in palatability and difficult to digest,which limits the development of staple food and high-value products.This topic plans to use brown rice as raw material,and sodium bicarbonate was applied to the cooking process of brown rice.The effects of sodium bicarbonate on the cooking quality,nutritional composition,starch structure and properties of brown rice were studied,in order to improve the cooking and eating quality of brown rice and provide a new feasible method for improving the cooking quality of brown rice.The main conclusions of this thesis are as follows:1.The addition of sodium bicarbonate had a significant effect on the cooking quality of brown rice.Sodium bicarbonate was beneficial to water absorption of brown rice during soaking.When brown rice was soaked at the same temperature,the Low field Nuclear Magnetic Resonance analysis showed that the peaks of T22 and T23 in brown rice soaked in bicarbonate moved to the right,and the peak area was significantly higher than that of brown rice soaked in distilled water.With the increase of cooking time,brown rice continuously swelled and gelatinized,resulting in surface cracks and whiteness in the cooking process.Sodium bicarbonate could shorten the time of surface cracks and whiteness.Compared with brown rice without sodium bicarbonate,with the increase of sodium bicarbonate concentration from 0 to 1%,the time required for cooking to crack and show white decreased from 17min to 13min,the best cooking time decreased from 23.42min to 15.91min,the water absorption rate increased from 10.03%to 15.76%,the expansion rate of rice increased from 212.30%to 245.40%,the pH value of rice soup increased from 7.02 to 8.87,and the solid content of rice soup did not change significantly.Sodium bicarbonate can also cause the viscosity of whole brown rice to change significantly.With the increase of sodium bicarbonate concentration,the peak viscosity,valley viscosity,disintegration value,final viscosity and retrogradation value of brown rice flour decreased significantly.2.The addition of sodium bicarbonate had a significant effect on the eating and nutritional quality of brown rice.After cooking with sodium bicarbonate,the color of brown rice deepened,its L value gradually decreased,B value and ΔE gradually increased,and A value showed a trend of increasing at first and then decreasing.The organization status of brown rice changed greatly.When the concentration of sodium bicarbonate is 0.4%and above,the cohesiveness among the grains of brown rice is enhanced and the white appearance of the grains is increased.The effect of sodium bicarbonate on the appearance of brown rice is that the surface wrinkles and cracks increase obviously,and the change is most obvious when the concentration of sodium bicarbonate is 0.4%-0.6%.In terms of texture characteristics,with the increase of sodium bicarbonate concentration,the hardness,elasticity,chewiness and stickiness of brown rice gradually decreased,while the stickiness gradually increased.In sensory evaluation,with the increase of sodium bicarbonate concentration,the smell,appearance,taste,palatability and texture of brown rice showed a trend of first increasing and then decreasing.When the concentration of sodium bicarbonate is 0.4%,brown rice has the best sensory quality.When sodium bicarbonate is added,the content of amines,esters,aldehydes and other flavor substances in brown rice will increase,and the brown rice will have unpleasant smell.In addition,sodium bicarbonate has no significant change on the content of protein and cellulose in brown rice,but it can increase the content of reducing sugar and decrease the content of vitamin B1,vitamin B2 and vitamin B3 in different degrees.3.Sodium bicarbonate has great influence on the structure and physicochemical properties of brown rice starch.After cooking brown rice with sodium bicarbonate,the starch molecular chains will be degraded to a certain extent,and the proportion of short chain fa in rice soup does not change significantly,but the proportion of Fbl increased significantly,while the proportion of Fb2 and Fb3 decreases gradually.Sodium bicarbonate can reduce the short-range ordered structure of brown rice starch,significantly reduce the initial gelatinization temperature,and significantly increase the peak temperature,end temperature and gelatinization enthalpy.The analysis of gelatinization characteristics showed that sodium bicarbonate was beneficial to starch gelatinization,which significantly increased its peak viscosity,final viscosity and retrogradation value,while decreased its valley viscosity.The analysis of gelatinization characteristics showed that sodium bicarbonate was beneficial to the gelatinization of starch,and the peak viscosity,final viscosity and retrogradation value increased significantly,while the valley viscosity decreased significantly.Sodium bicarbonate does not change the fluid type of brown rice starch.Starch is a pseudoplastic fluid without yield stress and has shear thinning phenomenon.However,with the increase of sodium bicarbonate concentration,the thixotropy of starch decreased at first and then increased.