米糠挤压膨化对其毛油品质及脱色效果的影响

The influence of extrusion on the quality and decolorization effect of crude rice bran oil

对膨化米糠和未膨化米糠进行浸出取油，之后对浸出毛油进行吸附脱色，通过对两种毛油品质及脱色效果的比较，考察米糠挤压膨化对其毛油品质及脱色效果的影响。结果显示：米糠膨化后其浸出毛油酸值较未膨化米糠明显降低、维生素E含量稍有降低、谷维素含量有所升高，色泽明显加深。对两种毛油进行吸附脱色，白土添加量为2％、4％、6％时，未膨化米糠较膨化米糠的毛油脱色率平均高出9．47％。由此可知，挤压膨化处理能使米糠浸出毛油色泽加深且新生色素较难脱除。膨化米糠在高温高湿（50℃，75％湿度）条件下储存60d后，米糠浸出毛油的酸值由7．5mgKOH／g升高至32．64mgKOH／g，色泽加深，维生素E含量明显降低，对其进行吸附脱色，其脱色率较新鲜膨化米糠浸出毛油脱色率降低28％～34％。可知，米糠经膨化后虽然稳定性得到提高，但不良储存条件仍然会造成毛油酸值升高、色泽加深且难以脱除。

In this study, crude oils were got from extruded rice bran and un-extruded rice bran by solvent extraction. Then the influence of extrusion on the quality and the decolorization effect were studied by comparing two kinds of crude rice bran oil. The results showed that the extruded rice bran was compared with un-extruded rice bran, the acid value and the content of Vitamin E decreased, while the oryzanol content increased. At the same time, the color of crude oil extracted from the extruded rice bran deepened significantly. The adsorption bleaching test showed that with the dosage of 2%, 4%, 6% clay, the rates of adsorption bleaching of un-extruded rice bran oil were all higher than that of extruded rice bran oil by an average of 9.47%. Accordingly, extrusion processing could make the color of rice bran oil deepened and these new kinds of pigment were relatively difficult to remove. However, when the extruded rice bran was stored on the condition of high temperature and high humidity （ 50 ℃, the humidity of 75% ） for 60 days, the acid value of crude oil extracted from the rice bran raised from 7.5 mgKOH/g to 32.64 mgKOH/g, the color deepened and the content of Vitamin E decreased obviously. And the adsorption bleaching test showed that under the same dosage of clay, the decoloring rates reduced by 28%-34% than the flesh extruded rice bran. Therefore, even the stability of rice bran was improved during the extrusion, it was not suitable to storage for a long time under the bad environment. Otherwise it might result in the crude rice bran oil＇ s acid value increasing and color deepening, and might cause it difficult to remove the pigment of the crude oil.