小桐子油的精炼及其氧化稳定性

以小桐子毛油为研究对象,通过碱炼脱酸、活性白土脱色、真空水蒸气脱臭对小桐子油进行精炼获得小桐子精炼油,研究了精炼前后小桐子油理化性质和脂肪酸组成的变化,同时,采用烘箱加热加速氧化油脂法研究小桐子精炼油的氧化稳定性,并预测小桐子精炼油的货架期。结果表明,精炼后油脂的色泽由(11.00±0.00)降低至(4.00±0.00),水分及挥发物含量由(7.50%±0.26%)降低至(0.50%±0.19%),酸值由(6.62±0.02) mg KOH·g-1降低至(0.26±0.01) mg KOH·g-1,碘值、皂化值和平均分子量无显著变化,精炼后分别为(104.37±0.24) g·100 g-1、(191.78±0.16) mg KOH·g-1和(877.57±2.43) g·mol-1;精炼前后脂肪酸组成变化不显著,精炼后主要脂肪酸组成为棕榈酸(13.36%±0.15%)、硬脂酸(4.25%±0.03%)、油酸(32.61%±0.10%)和亚油酸(43.36%±0.26%),其中不饱和脂肪酸含量达(75.97%±0.36%);氧化稳定性研究结果表明,小桐子精炼油储存温度越高,POV值越高,添加特丁基对苯二酚(TBHQ)、丁基羟基茴香醚(BHA)和维生素E(V_E)抗氧化剂后小桐子精炼油POV值降低,当添加0.02% TBHQ时,抗氧化性能较佳,可使小桐子精炼油在储存温度20 ℃条件下的货架期延长到208 d。

The refining and the oxidative stability of jatropha oil

Refined jatropha oil was obtained by alkali refining,bleaching,and deodorization of crude jatropha oil,the effect of refining process on the physicochemical property and fatty acid composition of oil,the oxidative stability of refined jatropha oil were studied by method of calefaction and acceleration with oven,and the shelf life of the refined jatropha oil was estimated. Results demonstrated that color of refined jatropha oil was reduced from(11.00±0.00)to(4.00±0.00),water and volatile matter contents was decreased from(7.50%±0.26%)to(0.50%±0.19%),acid value was decreased from(6.62±0.02) mg KOH·g-1 to(0.26±0.01) mg KOH·g-1,iodine value,saponification value,and average molecular weight had no significant changes which was(104.37±0.24) g·100 g-1,(191.78±0.16) mg KOH·g-1,and(877.57±2.43) g·mol-1 g·mol-1 respectively for refined jatropha oil. Fatty acid composition had no significant changes which was composed mainly of palmitic acid(13.36%±0.15%),stearic acid(4.25%±0.03%),oleic acid(32.61%±0.10%),and linoleic acid(43.36%±0.26%),and the unsaturated fatty acids content was up to(75.97%±0.36%). The results of oxidation stability demonstrated that the higher storage temperature of refined jatropha oil the higher POV,and the addition of antioxidant such as tertiary butylhydroquinone(TBHQ),butylated hydroxyanisole(BHA)and Vitamin E(V_E)was decreased the POV,and the most longest shelf-life of 208 d could be extended by adding 0.02% TBHQ as antioxidant with storage temperature was 20 ℃.