餐饮废弃油的理化性质与成分分析

Chemical properties and compositions analysis of waste cooking oil

以餐饮废弃油为主要研究对象,对其密度、折光率、酸值等理化性质进行了测定;采用核磁共振氢谱技术对比分析了油烟机废弃油与大豆油的差异,并采用气质联用技术表征了油烟机废弃油加热处理前后主要的化学成分变化情况。结果表明:食堂餐饮和油烟机废弃油的密度和折光率较正常油脂稍微增高;然而酸值和含水量大幅增加,最高酸值达到10 mg KOH/g以上;GC-MS分析显示油样未发生明显的变质,但加热处理之后,分子发生了降解反应,小分子成分增多,其化学成分更为复杂。油烟机废弃油的氢谱显示不饱和酸以油酸为主,少量烯键发生了酸败的转化,与GC-MS检测结果相吻合。核磁共振与气质联用双重检测的方法可以更准确地反映油脂的品质。

Three kinds of waste oils and two nature edible oils were used as raw material,and the physical properties of them,such as density,refractive index,acid value,saponification value,were measured.!H-NMR and GC-MS were employed to detect the com-position of the waste cooking oil from rangehood(LWO).The results showed that the refractive index and saponification value of all samples are not higher than each other,but the value of water content of canteen catering waste oil is the higher,whose acid value exceeds10mgKOH/g.The1H-NMR spectra of LWO shows that the main unsaturated organic acid is oleic acid,and a mild rancidi-ty has been formed derived from a small amount of olefinic bond oxidation.According to the result of GC-MS,The main compositions of the LWO are organic fatty acids and their ester,as well as a few of decomposing products,however,the obvious changes would be found after heated for9days at60X^.The quality of oils could be accurately reflected by the dual detection method of nuclear mag-netic resonance and gas chromatography mass spectrometry.