高酸值米糠毛油碱炼脱酸工艺及条件的优化研究

摘要

The two steps alkali refining process of crude rice bran oil with high acid value was carried out. With yield of alkali refining, bleaching rate, loss rates of oryzanol and sterol as indexes,the influence of mass fraction of lye on alkali refining effects of the first step and the second step alkali refinings was investigated and compared with the one step alkali refining process. The results showed that with mass fraction of lye increasing, the yields of alkali refining of the first step and the second step alkali refinings changed little in the two steps alkali refining process, and the bleaching rate of the first step alkali refining reached the highest when the mass fraction of lye was 14. 24%,while it presented fluctuation in the second step alkali refining;low mass fraction of lye was beneficial to the retention of oryzanol and sterol in the second step alkali refining of the two steps alkali refining process;comparing with one step alkali refining process, the yield of alkali refi-ning increased by 4. 89 percentage point on average and the loss rate of oryzanol decreased by 5. 87 percentage point on average in the two steps alkali refining process under the condition of the same mass fraction of lye;the bleaching rate improved by 9. 25 percentage point on average and the loss rate of sterol reduced by 12. 64 percentage point on average when mass fraction of lye (8. 07% -14. 24%) was low. In short, for crude rice bran oil with high acid value, two steps alkali refining had obvious advantages in increasing the yield of alkali refining and bleaching rate and decreasing the losses of oryzanol and sterol when mass fraction of lye was below 14. 24%.%以高酸值米糠毛油为原料，采用两次碱炼脱酸工艺，以碱炼得率、脱色率、谷维素损失率、甾醇损失率为考察指标，研究碱液质量分数对两次碱炼脱酸工艺中一次、二次碱炼效果的影响，并与一次碱炼脱酸工艺进行比较。结果表明：随碱液质量分数的增大，两次碱炼脱酸工艺中的一次、二次碱炼的碱炼得率变化不大，一次碱炼脱色率在14.24%时最大，二次碱炼脱色率呈起伏变化；两次碱炼脱酸工艺中二次碱炼时采用较低的碱液质量分数有利于甾醇和谷维素的保留；与一次碱炼脱酸工艺相比，两次碱炼脱酸工艺在相同碱液质量分数条件下，油脂碱炼得率平均提高4.89个百分点，谷维素损失率平均降低5.87个百分点；在碱液质量分数较低(8.07%~14.24%)时，脱色率平均提高9.25个百分点，甾醇损失率平均降低12.64个百分点。对于高酸值米糠毛油，采用两次碱炼脱酸工艺和质量分数为14.24%以下的碱液，对提高碱炼得率和脱色率以及减少谷维素和甾醇的损失都具有明显优势。