Influences from tea seed storage time on production rate and quality of tea seed crude oil

Abstract: The fermentation process for tea seed oil production is a brand-new process for vegetable oil production, which is mainly composed of 4 parts: cleaning and soaking of tea seed, pulp refining processing of tea seed by adding water, fermenting of tea seed water slurry, and producing of crude oil by heating the top layer that floats on the surface of fermented tea seed water slurry. Compared with the traditional squeeze process, the fermentation process has the advantages of high yield and good quality of crude oil, especially for the production of tea seed oil and camellia oleosa seed oil. When the fermentation process is used to produce tea seed oil, the whole oil content of tea seed is divided into 5 parts: crude oil, oil content of filter residue, oil content of oil residue, oil content of fermentation precipitation and oil content of starch. However, only crude oil among them is our target product. The oil content increase of filter residue, oil residue, fermentation precipitation and starch will cause production rate of crude oil to reduce, and therefore, all of them are called residuum. In order to reveal the influences of tea seed storage time on production rate and quality of tea seed crude oil, tea seed was sampled once every 2 weeks from the storied tea seed, tea seed crude oil was produced from the sampled tea seed by fermentation process, and the oil contents of different residua and the important quality indices of crude oil were determined. Under conditions of natural temperature, after tea seeds were stored for 47 weeks, crude oil production rate decreased by 23.5%, acid value and peroxide value increased by 44.88% and 69.4%, respectively, and the oil color did not change significantly. The masses of filter residue and fermentation precipitation were increased by 20.27% and 23.35%, respectively. The masses of starch and oil residue were reduced by 6.13% and 3.64%, respectively. The oil contents of filter residue, fermentation precipitation, starch and oil residue were increased by 15.63%, 22.77%, 206% and 12.88%, respectively. The influence of masses of fermentation precipitation on crude oil production rate was positive, nevertheless, the ones of masses of starch, oil residue and filter residue were negative. The influence of oil content of fermentation precipitation and filter residue on crude oil production rate was positive, however, the ones of starch and oil residue were negative. The sort order according to their influence degree was: Oil residue > starch > filter residue > fermentation precipitation. The results from comprehensive analysis showed that filter residue was the major factor leading to decreased crude oil production rate with the storage time, and its negative contribution accounted for 79.28%. The tea seed stored for 47 weeks can still be used for production of tea seed crude oil. Tea seed storage is inevitable in the production process of tea seed oil. The storage time affects directly the yield of tea seed oil and economic benefits of vegetable oil production enterprise. Therefore, carrying out researches on the effects of storage time on the yield of tea seed crude oil has a realistic significance.