Optimization of ultrasonic-assisted extraction of pigment from red rice by response surface methodology

Studied had shown that the maximum absorption peak of the red rice pigment in ultraviolet- visible light area was 276nm.The effects of variables on extraction yields of red rice pigment, such as ultrasonic power, liquid- solid ratio, extraction temperature and extraction time was investigated by single factor experiments.The optimum extraction conditions were obtained by using response surface methodology, as follows: ultrasonic power 135W, liquid-solid ratio 16 ∶1 ( mL·g- 1) , extraction temperature 53℃, extraction time 30min.Under these conditions, the natural pigment of pigment from red rice was 7.51, the predicted extraction yield of pigment from red rice was 18.68% with a relieve error of 0.14% when compared to the actual yield, 18.42%.Thus, the optimized extraction conditions are reliable.