Study On The Methods For Determination Of Adulterated Camellia Oil

The camellia oil is a kind of healthy edible oil with high nutritional value. Lack of olive oil in China, but rich in camellia oil. Now the camellia oil is becoming more and more popular all over the world, and the acreage, yield and demand of camellia oil are growing. Because the price of the camellia oil is so high, Some peddlers made an illegal means, mixing cheap oils into camellia oil to seek high profits, which greatly damaged the interests of consumers.Guangxi is one of the province is rich in camellia oil, in view of the adulteration phenomenon in camellia oil,3characteristics such as acid value, peroxide value, iodine value were analyzed, using15batches of Semi refined camellia oil as tested samples. Five common vegetable oils, including sesame oil, sunflower oil, peanut oil, corn oil, and rapeseed oil were mixed into camellia oil at different ratios(5%,10%,20%,30%,40%), respectively. In order to establish camellia oil adulteration identification method, GC fingerprint and differential scanning calorimetry (DSC) were applied to identify camellia oil adulteration. Quantitative identification model of identification of camellia oil adulteration was built based on DSC cooling thermal profiles. The main results are as fellows:1. The physical and chemical quality and the main fatty acid composition of the samples of15batches of Semi refined camellia oil were analyzed. Iodine value in the range of83.54-88.81g/100g. Camellia oil is mainly composed of palmitic acid, stearic acid, oleic acid, linoleic acid, and arachidonic acid, among which the content of oleic acid is the highest, in the range of76.2893-81.8493%, follow by linoleic acid and palmitic acid, in the range of7.0331-11.8765%and7.8840-8.7655%, respectively, and a small amount of stearic acid and linolenic acid, in the range of1.8045-2.2818%and0.2716-0.6560%, respectively.2.The GC fingerprint of camellia oil was established by using15batches of semi refined camellia oil and6common fingerprint peaks were found. The similarity was calculated by Cosine method, the similarity between the15batches of semi refined camellia oil with the reference GC fingerprint was above0.9989. The GC fingerprints of camellia oil blended with different other vegetable oils in different proportion were determined. By calculating the similarity between the camellia oil reference GC fingerprint and the GC fingerprints of the adulteration sample, detecting adulteration of camellia oil with other vegetable Oils. The similarity was below0.9989, at sesame oil≥10%, at sunflower oil≥10%, at corn oil≥>10%, at peanut oil≥20%, at rapeseed oil≥30%, respectively.3. The crystallization and melting enthalpy of camellia oil and camellia oil adulterated with sesame oil, sunflower oil, peanut oil, corn oil, and rapeseed oil were studied by using differential scanning calorimetry, to find a fast and easy way to detect other oils in camellia oil. Camellia oil and the other oils could be characterized by significantly different cooling and heating DSC thermal profiles. The major endothermic peak at-6.65±0.54℃and the exothermic peak at-36.54±0.55℃for camellia oil. The major endothermic peak and the exothermic peak of the other vegetable oils at lower temperature. The analysis of variance of significance(p<0.05) shows that there were significant difference between the camellia oil and the camellia oil adulterated with sesame oil, peanut oiL, corn oil at5%adulteration level, and the camellia oil adulterated with sunflower oil and rapeseed oil at10%adulteration level. With the increase of adulteration ratio, the major endothermic peak and the exothermic peak shifted towards lower temperatures. DSC has good precision (RSD<7%) and linear range with R2of0.9993. Regression analyses using stepwise multiple linear regression were used to predict the percentage adulterant, got5quantitative identification models, the feasibility of the5models were tested, with mean error of1.2620%, and can meet detection requirement.