Study On Improving The Conventional Corn Wet Milling By Ultrasonic-Assisted Extraction

Ultrasonic assisted extraction was used to improve the conventional corn wet-milling,and the modified corn wet-milling technology was established.The corn steeping time and sulfur dioxide content were reduced.The starch yield was improved without compromise of the purity of the extracted starch.The modified technoloy of corn wet milling was evaluated by the analysis of starch properties.With common commercially available hybrid corn as raw material,a five factorial design was employed with corn steeping time,level of sulfur dioxide,ultrasonic power,ultrasonic treatment time,and ultrasonic solid-liquid ratio by ultrasonic assisted extraction of corn starch.Using single factor and orthogonal experiment to optimize the ultrasonic assisted extraction of corn starch process conditions.Corn starch yield as the index showed that the optimum process conditions of ultrasonic assisted extraction of corn starch were:corn grains steeping 32 h,sulfur dioxide content of 0.05%?w/w?,ultrasonic treatment for 15min,ultrasonic treatment power of 200 W,ultrasonic treatment solid-liquid ratio 1:1?g/m L?,the corn starch yield was?68.96±0.17?%.The content of SO₂ decreased by 3/4,corn steeping time reduced by 1/3,corn starch yield increased by 10%,and the starch purity remain the same.With high amylose corn grains as raw materials,according the different of high amylose maize steeping time,level of sulfur dioxide,ultrasonic power,ultrasonic treatment time,solid-liquid ratio to carry out single factor and orthogonal experiments.As the index of high amylose maize starch yield,the optimal conditions for ultrasonic assisted extraction were:high amylose maize steeping 36 h,sulfur dioxide of 0.05%?w/w?,ultrasonic processing time of 15 min,ultrasonic power of 200 W,and solid-liquid ratio of 1:1?g/m L?,the high amylose maize starch yield was?56.68±0.31?%.Content of SO₂ decreased by 3/4,corn steeping time reduced by 1/4,high amylose maize starch yield increased by 11%,and the starch purity remain the same.The modified technoloy of corn wet milling was evaluated by the analysis of starch properties.Comparing corn starch and high-amylose starch of ultrasound assisted extraction with the starch of conventional wet milling extraction.It was found that crystalline structure was not destroyed.Corn starch was still crystallization of type A and high-amylose maize starch is crystallization type B.The yellowing degree significantly reduced,and the average particle size did not change significantly.Starch granules of ultrasonic assisted extraction did not change observed by optical microscope and scanning electron microscope.The gelatinization properties result showed that viscosities of starch from sonication were significantly higher than those starch from conventional wet milling.The gelatinization temperature and gelatinization enthalpy did not change significantly,indicating that ultrasonic treatment did not change the thermal stability of starch.For the rheological properties of starch,the storage modulus of starch from ultrasonic assisted extraction were higher than that of starch extracted by traditional wet milling.It showed that elasticity of the gel fromed starch of ultrasonic-assisted extraction was stronger.Ultrasonic-assisted extraction technology was practical.