Study On Oil Components,Starch Properties And Starch-Oil Compound Of Tea Seed

Tea tree(Camellia Sinensis(L.)O'Kuntze)is one of the important economic crops in our country.In 2019,the area of tea gardens was 3.065 million hectares,and the annual output of tea seeds reached 2.299 million tons.Oil and starch are the two main components of tea seeds.Tea seed oil is a potential woody oil resource,and tea seed starch can be used as a novel and unique starch resource.The complex of amylose and fatty acid is called the fifth type of resistant starch(RS5),which is of great significance for the prevention and control of chronic diseases such as type 2 diabetes and colon cancer.However,the lack of a full understanding of the oil and starch in tea seeds has led to the waste of large amounts of tea seeds.Therefore,carrying out research on the oil and starch properties of tea seeds and evaluating the compound effect of starch-oil will provide an important reference for the subsequent development and utilization of tea seeds.In this research,tea seeds are used as materials,and a variety of common edible oils and starches are selected as references.The composition of oil,the physicochemical properties of starch and functional properties of starch-oil complexes of tea seeds are studied.The main results are as follows:1.The main components of tea seed oil are palmitic acid(about 17%),stearic acid(about 3%),oleic acid(about 56%)and linoleic acid(about 21%).The proportion of main fatty acids is relatively stable between varieties and after finishing.The ratio of saturated fatty acid(SFA): monounsaturated fatty acid(MUFA): polyunsaturated fatty acid(PUFA)is 1:2.6:1,which is close to peanut oil(1:2:1.5)and meet the health oil standards.Although the SFA content of tea seed oil is higher than that of camellia oil and olive oil,the content of linoleic acid is also significantly higher than that of them.In addition,trace amounts of linolenic acid and squalene acid were also detected in crude oil.10 phenolic substances were separated and identified from tea seed oil by GC-MS,namely naringenin,isorhamnetin,chlorogenic acid,catechins,caffeic acid,gallic acid,epigallocatechin,rutin,quercetin and kaempferol.These active substances have strong antioxidant activity.They can inhibit the proliferation of human colon cancer cells HCT116 and mouse colon cancer cells CT26 and cause the necrosis of cancer cells.The results show that tea seed oil has a reasonable and stable fatty acid ratio.It is rich in unsaturated fatty acids and antioxidant active substances,which has high nutritional and health value.2.Tea seed starch granules,compared with starches from other crops,are more regular in shape,and more uniform in size.It is A-type or C-type starch,and has a higher proportion of fa amylopectin than other crops.Wun4 can be fully gelatinized at a relatively low temperature(60?70 ?).The gelatinization temperature range of Wun4 is short(9.62 ?).In the simulated digestion process,the RDS content of tea seed starch(80?82%)is comparable to potato starch and pea starch,and is significantly lower than other starches.The RS content(9.7?11.9%)is only lower than pea starch.It shows the characteristics of slow digestion and digestion resistance.At the same time,the gelatinization viscosity of tea seed starch is high.The final viscosity reached4000?6800 cp,which was significantly higher than that of other crops.The starch gel of tea seed starch has a high viscosity-hardness ratio,and exhibits good palatability and moderate elasticity.However,the retrogradation degree(R%)of tea seed starch is relatively high,ranging from 33.2 to 44.6%.It needs to be modified appropriately to reduce its retrogradation and aging tendency when used in the application fields that require high long-term stability.3.The starch-oil composite rate is affected by the AAC content of starch and the saturation and chain length of fatty acid.The compounding effect of tea seed oil is worse than that of C16;and the compounding rate of high AAC starches such as tea seed starch is relatively high.The compounding efficiency of tea seed starch and C16 is 66.88%,second only to cassava starch(80.56%)and potato starch(81.67%).The presence of lipids reduces the gel transparency and increases the internal pores of the starch.The microporous structure can be observed under the electron microscope.The formation of RS5 significantly affects the physicochemical properties of starches: the crystal structure of starches changed from the original type;the starch gelatinization temperature increased,and the thermal stability improved;the digestion characteristics changed,such as the RDS dropped sharply and the RS increased significantly.The variation range of different starches were different.For example,the final RS content of tea seed starch was higher,while the growth rate of SDS of ordinary rice starch was higher.Therefore,starch-oil composite modification can be used to modify the thermal stability and digestion properties of starch.In summary,tea seed oil is a high-quality edible oil.The physicochemical characteristics of tea seed starch meet market demand.The functional properties of starch-oil complex have been improved,which has great potential in food and industrial applications.These research results provide a theoretical basis for the comprehensive utilization of tea seeds in the future,as well as new ideas for the healthy development of the tea industry.