高油酸花生油低温分层现象分析

高油酸花生油以其营养价值高、储藏期长等优点越来越受到广大消费者的青睐。在低温条件(4~6℃)下,普通花生油会发生凝固现象,而高油酸花生油则不会完全凝固,而是产生分层现象。为了探究高油酸花生油低温下分层的原因,对分层后的高油酸花生油上、下层的脂肪酸及甘油三酯组成进行了分析,发现下层油中饱和脂肪酸(SFA)含量显著增加,特别是超长链饱和脂肪酸(VLCSFA)的含量是上层油的3.8倍。甘油三酯分析表明,下层油中携带2个SFA的甘油三酯(S2U)显著富集,特别是携带VLCSFA的S2U型甘油三酯,其在下层油中的含量是上层油中含量的7.1倍。由此推断,大量携带VLCSFA的S2U型甘油三酯在低温下结晶析出是导致高油酸花生油分层的主要原因。

Mechanism of stratification of high oleate peanut oil at low temperatures

Due to high nutritive value and prolonged storage life, the high oleate peanut oil has been increasingly interested by customers. At low temperatures(4-6 ℃), the normal peanut oil is solidified, but the high oleate peanut oil is divided into two layers: the top layer is liquid and the bottom layer is solid. To investigate the reasons,the fatty acid and triacylglycerol(TAG) compositions of top and bottom layers were analyzed, respectively. The content of saturated fatty acid(SFA) in the bottom layer was significantly higher than that in the top layer, especially for very long chain saturated fatty acid(VLCSFA), which in the bottom layer was 3.8 folds as much as that in the top layer. The TAGs containing two SFAs(S2 U) were significantly enriched in the bottom layer. Furthermore, the S2 U with VLCSFA in the bottom layer was 4.1 folds more than that in the top layer. Therefore, the solidification and precipitation of S2 U with VLCSFA at low temperatures is the main reason for stratification of high oleate peanut oil.