| In order to provide a theoretical basis for the accurate and moderate processing of edible oils, the composition of oil samples was changed by adding β-carotene and different fatty acids using soybean oil as the oil sample medium, and the effects of different vegetable oil substrates and alkali refining conditions (lye mass fraction, excess alkali addition, alkali refining temperature, and alkali refining time) on the removal rate of β-carotene in oils and the refining yields of oils in alkali refining process were investigated. The changes of acid value of oils after deacidification under different vegetable oil substrates and alkali refining conditions were determined. The results showed that the fatty acid type had a significant effect on the removal rate of β-carotene, and the saturated soap palmitic acid soap generated by alkali refining had the highest removal rate of β-carotene (5.92%), while the unsaturated soap linolenic acid soap had the lowest removal rate of β-carotene (2.57%); when the content of free fatty acid was 1.2%, the removal rate of β-carotene was the highest (4.09%), the more the β-carotene content in oils, the higher the β-carotene removal rate; the medium-strong alkali with the lye mass fraction of 12%-18% was conducive to the removal of β-carotene, with the removal rate of β-carotene ranging from 3.73% to 4.30%; with the increase of excess alkali addition, the removal rate of β-carotene first increased and then decreased, and the highest removal rate of 4.09% was found when the excess alkali addition was 0.1%; the lower the alkali refining temperature was, the higher the removal rate of β-carotene was, and the highest removal rate of β-carotene was found at 30 ℃ (4.46%); with the prolonging of the alkali refining time, the removal rate of β-carotene increased continuously, and the increase of removal rate slowed down after more than 30 min of alkali refining; palmitic acid and stearic acid significantly reduced the refining yield of oils; with the increase of lye mass fraction, excess alkali addition, alkali refining temperature, alkali refining time, and the content of free fatty acids, the refining yield of oils showed an overall decreasing trend, and β-carotene content had no effect on the refining yield of oils. Except for vegetable oils containing a large amount of lauric acid, alkali refining could effectively control the acid value of oils in the range of 0.04-0.22 mgKOH/g. In conclusion, low temperature and the medium-strong alkali can help the removal of β-carotene, and the appropriate shortening of alkali refining time can help the retention of β-carotene. |
