Study On The Effects Of Electron Beam Irradiation In The Edible Qualities Of Rice

In this study, different dose of electron beam was used to irradiate rice and then the irradiation effects on rice cooking quality,pasting properties of rice starch and rice flavor were analyzed, and finally the best process parameters of the electron beam irradiation were determined.The results were as follows:(1) The moisture content of the rice and soak water absorption did not change obviously after irradiation(P>0.05), with the increasing of irradiation doses, the heat absorption and expansion of rice fell markedly(P<0.05), the heat absorption and expansion of rice reduced by 25.5% and 21.3% respectively at dose of 3 kGy compared with the rice not irradiated; Compared with the rice not irradiated, at dose of 3 kGy, the rice pH reduced from 7.30 to 6.73, dry matter of rice water was reduced by 13.5%, rice water iodine blue value decreased 0.05(P < 0.05); The total color difference ?E=7.05>6.0 at dose of 3 kGy, seriously affect the eating quality of rice; With the increasing of irradiation doses, hardness and hardness/viscosity values of rice decreased significantly(P< 0.05). When the radiation dose increase to 5 kGy, the hardness and hardness/viscosity value of rice reduced by 27.9% and 46% respectively, the elasticity of rice dropped slightly(P>0.05). Taking into account changes in cooking qualities of rice, the irradiation dose of electron beam irradiation of rice less than 3 kGy is more appropriate.(2) The gelatinization characteristics of rice starch changed a lot after irradiation. With the increasing of irradiation doses, the peak viscosity, the minimum viscosity, attenuation, final viscosity, and the setback of the rice showed a decreasing trend(P<0.05). The peak viscosity, the minimum viscosity and the final viscosity of rice starch reduced by 40.36%, 62.61% and 51.64% respectively compared with the rice not irradiated at dose of 3 kGy. The peak viscosity and the setback of the rice decreased significantly after irradiation indicate that a lower dose of the electron beam can make rice texture softening and improve eating quality of rice; With the increasing of irradiation doses, pasting range of rice starch increases significantly larger. The pasting range of rice increased 7.01%, 26.01% and 47.05% at dose of 1 kGy, 3 kGy and 5 kGy respectively. To and Tp dropped but Tc rise slightly(P>0.05). Also with the increasing of irradiation doses, the gelatinization enthalpy of rice starch appear significant downward trend(P<0.05). Compared with the rice not irradiated, the gelatinization enthalpy of rice starch reduced by 11.89%, 25.24% and 33.99% respectively at dose of 1 kGy, 3 kGy, 5 kGy. Taking into account changes in rice starch pasting properties, the proposed radiation dose less than 3 kGy is more appropriate.(3) The rice flavor compounds changed a lot after irradiation,the most significant change is the mass fraction of hydrocarbon and ester material. The volatile components of rice hydrocarbon species significantly reduced after irradiation. Compared with the rice not irradiated, the volatile components reduced by 32.3% at dose of 5 kGy. Acids remarkable increased, aldehydes,alcohols, acids and esters increases with the increase of the radiation dose before 3 kGy, when the radiation dose is increased to 5 kGy, the mass fraction of each component has decreased significantly.(4) The optimum dose of rice electron beam radiation is 0.7 kGy, the packaging material is nylon- polyethylene composite plastic, and the material thickness is 16 cm.When rice irradiated under this condition, the rice sensory score is the highest, rice taste good, hardness is appropriate and when chewing, there is a light faint scent.