| About 840.000 tons of tea seed was produced in our country every year. The tea seed contains 25%?35% oil and has been considered as novel food since 2009. However, the oil is prone to be metamorphic with a short shelf life during production and sales. This phenomenon was studied in this paper.At first, the basic indexes of samples sold in the market were analyzed, and the best sample was chosen for the subsequent experiments. The samples were firstly mixed and sealed with nitrogen, then saved under the condition of a specific temperature (37?,20?,50?) and illuminance (0 Lux,600 Lux,1200 Lux) respectively. A bottle of sample was taken for test within a certain period of time. The detect indicators included peroxide value, anisidine value, acid value, composition of fatty acids and volatile components in the sample. The results indicated that the peroxide value, the anisidine value and the acid value of tea seed oil had a significant correlation with the storage time (P<0.05), as well as the temperature. But the influence of light was not significant. This phenomenon was also found in the anisidine value and the acid value of tea seed oil. In addition, the main volatile substances of tea seed oil were hexanal or anti-2,4-sebacic acid mainly produced by the oxidation of linoleic acid and nonyl aldehyde mainly produced by oleic acid. What's more, the content of nonyl aldehyde was not very high during the earlier phase, but it showed a rapid upward trend in later stage. Besides, the effect of temperature on the oxidation rate of linoleic acid was more significant.The shelf life of tea seed oil under certain conditions can be described by Arrhenius equation with the peroxide value as an index. The result showed that light had little effect on the shelf life of tea seed oil, the El1, and El2 in the equation k= kd+El1· El2 were smaller than that can be calculated under different illuminance. So it was difficult to set the shelf life model by illuminance as variables. When temperature was chosen as variable the Ea and the kref value under different illuminance (within 1?1200 Lux) had no difference. This phenomenon validated the influence of light on the shelf life of tea seed oil was not significant. The shelf life model can be described as according to the average value of the Ea and the kref. And the shelf life of tea seed oil or the time required to achieve specific peroxide value can be calculated from this model. The model was verified by the conditions of 30? and 750 Lux and natural condition (the average temperature was 25?), and the standard errors were both within 0.20, which means the shelf life model can be used in predicting the shelf life of tea seed oil.In order to extend the shelf life of tea seed oil, the effect of tea flower on tea seed oil was also investigated in this paper. The result verified that the antioxidant effect of ethanol as extraction was better than tea flower dissolved by soaking. The stability indexes were almost 3.26 times and 2.73 times than the sample without tea flower, respectively. Furthermore, the shelf life extended about 174% and 135% in 50? accelerated oxidative stability experiments. Tea flower was replaced by polyphenols, which exhibited a similar result. The antioxidant effects of tea seed oil with tea flower (which was approved to be novel food in 2012) was compared with lipid-soluble catechins and common antioxidants (BHT, BHA and TBHQ). The result indicated that the antioxidant activities of tea flower extract are better than those of BHA and BHT, comparable to lipid-soluble catechins, but worse than TBHQ, which means that tea flower has a good effect on the extension of the shelf life of tea seed oil. |
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