拉曼光谱测定食品油脂的氧化

油脂是一种在食品工业中应用广泛的主要原料，其品质和抗氧化稳定性直接影响着食品的质量。因此，建立一种快捷、可靠、灵敏的食用油质量检测方法尤为重要。作者采用普通拉曼光谱对亚麻籽油、鱼油和山茶籽油的氧化过程进行分析，结果表明：974 cm-1处代表的反式结构在氧化过程中逐渐增多，特征峰的相对强度I974/I1442逐渐增加；1 265 cm-1处的代表的顺式双键在氧化过程中损失，其特征峰的相对强度I1265/I1442逐渐降低。以纳米银为基底，采用表面增强拉曼光谱（SERS）技术对亚麻籽油的氧化过程进行分析，结果表明：以正己烷为溶剂、50倍稀释条件下得到的SERS增强因子最大。对比亚麻籽油在储存过程中SERS和普通拉曼光谱在同一位置的特征峰相对强度的变化，发现两者反映的脂肪酸结构变化信息一致，且SERS更为灵敏。
Lipid is the main raw material of food industry，and its quality and oxidation stability directly affect the food quality. Therefore，it is highly necessary to develop a fast，reliable and sensitive technology to evaluate the quality of edible oil. In this paper，linseed oil，fish oil and camellia-seed oil were analyzed by Raman spectroscopy and surface-enhanced Raman spectroscopy. The results indicated that during the process of oxidation，the characteristic peak at 974 cm-1 which on behalf of the trans structure gradually increased，resulting in increase of relative intensity of I974/I1442，and the characteristic peak at 1 265 cm-1 which on behalf of the cis double bond gradually decreased，resulting in decrease of relative intensity I1265/I1442. With silver nanosubstrate，the highest analytical enhancement factor was achieved for linseed oil diluted 50 times with hexane by SERS analysis. The changes of intensity for the same characteristic peaks were similar between SERS and Raman spectroscopy，indicating similar structure information for fatty acids was obtained，and SERS analysis was more sensitive