加工工艺对油茶籽油氧化稳定性及酚类物质含量的影响

Effect of refining process on phenolic compounds and oxidation stabilities in oil-tea camellia seed oil

为了探究加工工艺对油茶籽油营养品质的影响,了解油酚类物质在加工工艺中的变化规律,该文从油茶籽油加工企业的生产线中取样,对压榨毛油和浸出毛油精炼工艺以及压榨毛油适度精炼工艺等不同工艺中油茶籽油中总酚、多酚组成及含量、抗氧化活性系数和油的氧化诱导时间等指标进行了测定。压榨毛油精炼工艺包括水洗、脱色、脱臭、冬化;浸出毛油精炼工艺包括碱炼、水洗、脱色、脱臭、冬化;压榨毛油适度精炼工艺包括脱胶、碱炼、水洗、冬化等工艺步骤。结果显示:压榨油茶籽毛油中总酚平均质量分数为103.06μg/g,显著高于浸出油茶籽油48.52μg/g(P<0.05);油茶籽毛油经过精炼工艺后总酚和总酚的抗氧化活性均呈现下降趋势,三种精炼工艺后油茶籽油中总酚分别下降了88.9%,86.7%和63.81%,总酚的抗氧化活性分别下降了88.3%,93.51%和83.25%。适度精炼相比普通精炼对于保留油茶籽油中的多酚有明显优势,前者精炼后油茶籽油中总酚及其抗氧化活性系数分别为37.82μg/g和9.33%,后者仅为11.41μg/g和4.71%。通过高效液相色谱测定发现,浸出油茶籽毛油精炼后仅含有少量肉桂酸,压榨毛油传统精炼后压榨油茶籽油中测到苯甲酸、芦丁和肉桂酸等3种多酚的质量分数分别为4.7、1.58和0.22μg/g,压榨毛油适度精炼后的油茶籽油中测到了单宁酸、绿原酸、表儿茶素等9种多酚,其中单宁酸和绿原酸的质量分数最高,分别为4.57和3.26μg/g;适度精炼后油茶籽油氧化诱导时间从初始的8.56 h增加到11.66 h,增加了26.63%;压榨毛油传统精炼后油茶籽油氧化诱导时间从8.14 h增加到10.42 h,增加了21.83%。研究结果表明,压榨毛油适度精炼相比传统精炼工艺对于保留油茶籽油中多酚等成分有明显优势,所生产的茶油具有更强的氧化稳定性。研究结果为油茶籽油中营养成分的保留提供了途径,为油茶籽油加工工艺选择提供参考。

This paper is aimed at studying the effect of refining processes on the quality of the camellia seed oil, and understanding the rule of phenols in camellia oil during refining. The camellia oil was sampled in local oil-tea camellia seed oil manufacturer, which was from 3 refining processes including squeezed oil refining process, leached oil refining process and squeezed oil＇s moderate refining process. The refining processes of squeezed oil included water washing, bleaching, deodorization, and dewaxing, the refining processes of leached oil included alkaline refining, water washing, bleaching, deodorization, and dewaxing, while the moderate refining processes of squeezed oil included degumming, alkaline refining, washing, and dewaxing. The total phenol content（TPC）, phenolic compound（PC）, oxidation resistance coefficient（AA） and oxidation induction time of these oil samples were detected. The results showed that, the TPC was higher in squeezed oil than that in leached oil, which were 103.06 and 48.52 μg/g, respectively. The TPC was declined by 88.9%, 86.7% and 63.81% after refining processes of squeezed oil, leached oil, and moderate refining processes of squeezed oil, respectively. The AA was declined by 88.3%, 93.51% and 83.25%, respectively in the 3 refining processes. Moderate refining process was better at the retention of TPC and AA in the study than traditional refining processes. The TPC and AA were 37.82 μg/g and 9.33% respectively in moderate refined oil, while 11.41 μg/g and 4.71% respectively in traditional refined oil. The same conclusion was got in the results of PC. There was only a small amount of cinnamic acid that was detected by high-performance liquid phase chromatography（HPLC） in the leached camellia oil after refining, while 3 PCs were detected in the squeezed oil after refining, which included benzoic acid, cinnamic acid and rutin, with the contents of 4.7, 1.58 and 0.22 μg/g, respectively. Nine PCs were detected in squeezed oil after moderate refining process, including tannic acid, chlorogenic acid, catechin, epicatechin, trans-cinnamic acid, rutin hydrate, coumarin, homovanillic acid, gallic acid and o-vanillic acid. The PCs with the highest content in squeezed oil after moderate refining process were tannic acid whose content was 4.57 μg/g and chlorogenic acid whose content was 3.26 μg/g. The oxidation stability of oils could be increased by refining processes. The oxidation induction time of oil before and after the moderate refining process was 8.56 and 11.66 h, respectively, with an increase of 26.63%, while the oxidation induction time of oil before and after the refining process was 8.14 and 10.42 h, respectively, with an increase of 21.83%. The conclusion is that moderate refining process is better at the retention of nutritional ingredients like PC, and the oil from moderate refining process will have higher oxidation stability. The results of the study provide the method of reserving nutrients in the oil-tea camellia seed oil, and the reference for the selection of refining processes and conditions for manufacturer. The correlation of single polyphenol and antioxidant stability of the oil will be studied in the future, and the determination of antioxidant activity will be improved in future research, too.