Effects Of Fermentation Technique On The Cadmium Content Of Rice

In recent years, grain has been wasting seriously caused by cadmium pollution. There is still a lot of cadmium exceeding rice circulating in food market, forming a potential health hazard for people. It is a urgent problem to be solved for digesting the cadmium-exceeding rice. According to numerous studies, fermentation can promote dissolution of protein and cadmium existed in rice by chelating with protein. So fermentation could be a possible way to solve the problem of cadmium-exceeded rice. In additional, there are many studies about reducing cadmium content in soil by electric chemistry method, which could be an effective method. In this study, our main task is to probe the change of cadmium in rice by natural thermostat fermentation and electric chemistry method.First of all, this research compared GFAAS method with Rapid Detection of Heavy Metals method. The results showed that the precision of RDHM method was higher than GFAAS method, but the accuracy of GFAAS method was better than RDHM method. There was no difference between GFAAS method and RDHM method.And then, this research studied the variation of protein and cadmium of rice samples dealt with natural thermostat fermentation and electric chemistry method. The results showed that the natural thermostat fermentation could reduce cadmium content by improving time(0-36h), temperature(30℃～45℃). Content of cadmium and protein changed in consistent with the change of time and temperature. Content of cadmium in rice could be reduced by lowering pH(3-6) and raising liquid ration(1/2-1/20), but content of cadmium and protein changed inconsistent. The electric chemistry method could reduce cadmium content by improving temperature(30℃～40℃), voltage(5V-20V) and buffer concentrations (0.025mol/L～0.1mol/L). Content of cadmium in rice could be reduced by lowering pH(3-6) and improving time(0-9h), but content of cadmium and protein changed in inconsistent.According to the analysis of least square fitting method between cadmium content and protein content in rice samples by these two methods, the results showed that the coefficient of correlation, R, equal to 0.72462 and 0.68728, P<0.01.Finally, the research confirmed the optimal solution of these two methods by orthogonal experiment. The most optimal option of natural thermostat fermentation is E3D3B2C1A2, they were time 36h, temperature 40℃, pH= 4, buffer concentration 0.15mol/L and solvent ratio 1:20.The cadmium reduction rate is 61.37%. The most optimal option of electric chemistry method is B2A3D2C3, they were temperature 45 ℃, pH= 5, buffer concentration 0.15mol/L and voltage 25V.The cadmium reduction rate is 62.68%.