Research On The Quality Change Of Tea Seed Oil In Oil Extraction Process

Tea seed is the seed of tea tree (Camellia sinensis O.ktze). Tea seed oil is the oil extractedfrom tea seed. Tea seed oil has been approved as a new source food in2010by the Ministry ofHealth officially. It is a high oleic acid edible vegetable oil and rich in lipid accompanyingcompounds naturally. But currently, the tea seed oil in the market often has been processedexcessively, and the lipid accompanying compounds have lost a lot. In order to explore thesuitable processing method of the tea seed oil, quality changes of tea seed oil in the oilextraction process has been analysed and discussed in this paper.Detected the basic indicators and lipid accompanying compounds content of collected teaseed extracted crude oil from thirteen provinces nationwide. Oil content (dry) of tea seed is28%to30%. The oil’s acid value is0.3to1.0mgKOH/g, peroxide value0.2to1.6meq/kg,and has good oxidative stability. The main fatty acids of tea seed oil are palmitic acid, stearicacid, oleic acid and linoleic acid; mean respectively15.53%,2.92%,57.28%, and22.30%.The tea polyphenols content is20to45mg/kg; total tocopherol250to450mg/kg, mostlyα-tocopherol; total phytosterols2000to3000mg/kg; squalene500to800mg/kg. The steroltypes of tea seed oil are different with general vegetable oil and its tea polyphenols contentmore than others. This is promising as a characteristic indicator of tea seed oil and can beused for its identification and fidelity.Determined quality indicators of tea seed oil that obtained by room temperatureextracting, cold-pressing and hot-pressing (heating temperature is80℃and120℃). Heattreatment at80℃and120℃has little difference with cold-pressing in acid value and OSIvalue. But peroxide value of120℃treatment increased significantly. In the experimentaltemperature range, tea polyphenols, squalene, sterols content after seeds heating areobservably more than cold one, increasing150%~192%,4%~22%,6~14%respectively.However, the heat treatment will reduce the tocopherol content5%~13%. In general, theappropriate heat treatment is advantageous to improve the quality of the tea seed oil.Then, further insight into the influence of seed frying temperature, seed frying time to teaseed oil’s quality. The result of orthogonal testing expresses the frying temperature is the mostimportant factor effecting tea seed oil. It affects all indicators except sterol content (verysignificant effect on acid value, peroxide value, trans-fatty acid and significant effect on otherindicators). Frying time just influence four indicators significantly except sterol. When seedfrying temperature between160and200℃, trans-fatty acids and benzo(α)pyrene levelsgenerally do not exceed the standard limit values. Overall consideration, the temperature ofhot-pressing should fry no higher than200℃, the frying time is10to15min and press about30min.Crude tea seed oil storage experiment for a period of6months has been done. Simulatedfactory’s practical situations, then explored the impact of light, temperature and tightness tothe quality of cold and hot pressing tea seed oil. The results show that the storage stability ofhot-pressing crude oil is better than cold-pressing one. The influence degree of each storagecondition on the oil quality is light, temperature and tightness. Therefore, dark storage is essential for tea seed oil, while maintaining stable storage temperature and low temperature ispreferred. After6months of storage, the acid value and peroxide value of crude oil bothincreased more than100%. OSI dropped more than65%. Tocopherol reduced by25%~50%,squalene reduced by55%~87%, and tea polyphenols reduced by25%~67%. But sterols lossrate is less than5%. By correlation analysis, the oxidation stability of hot pressing oil has ahigher correlation with phenols and the cold one is more related to squalene.Analysis the tea seed oil samples collected from different refining process, researchquality changes of the oil in the refining process. Deodorization is the main loss step oftocopherol, squalene and sterols. The loss rates are26.85%,36.39%and25.68%respectively.Tea polyphenols has the biggest loss in deacidification, loss rate is22.7%. In the wholerefining process, trans-fatty acids increased1.09%, PaB decreased85.87%and OSI valuereduced65.99%.This article conclusion has good guidance to tea seed pressing, crude oil storage andsubsequent refining process.