Study On Pressing Properties Of Several Oilseeds And Evaluate Quality On Pressed Cake、 Pressed Oil Of Several Oilseeds

Rapeseed and peanut kernel are the important bulk oil seeds in China, they are played an important role in the number of the domestic edible oil. Flaxseed and perilla seed are special seeds in China, because alpha linolenic acid are rich in these two kinds of oil seeds,they are main edible oil mainly taken up n-3 series fatty acid. In this article rapeseed、perilla seed and peanut kernel were used as the raw material to study on their material properties(include raw material composition、hardness and fragile)and observation of microscopic structure of the cotyledon cells in four oilseeds and the pressing cakes, then studied on the change of contents of protein、nitrogen solvable index(NSI) and composition of amino acid of four kinds of pressing cake. At last, the four kinds of oilseeds under the suitable conditions were pressed, then the quality index and hygienic index of the pressed oil and the hydrated degumming oil w ere analysed. The main results of the study are as follows: 1.In order to research on the processing technologies used to in the oil plants producing area and develop screw press in low resudual oil rate,the flaxseed、rapeseed、perilla seed and peanut kernel were used as the raw material to study on their material properties(include raw material composition、hardness and fragile). The small screw oil expeller(the single screw press was the integration of screws and screw shaft, the theoretical compression ratio was 11 throng measure and calculation) was used to press, moreover, the residual oil rate in cake was as the index. The effect of the water of pressing material, pressing temperature, environmental temperature and other factors on the residual oil rate in cake of four kinds of oil seeds were investigated. Through orthogonal and confirmative test, the optimize obtained pressing condition as: flaxseed、rapeseed: the water of press material 3%, pressing temperature 65℃, environment temperature 30℃. In the optimum conditions, residual oil rate in pressing cakes of rapeseed and flaxseed were respectively 9.31% and 8.01%;perilla seed and peanut kernel :the water of pressing material 4%, pressing temperature 65 ℃, environment temperature 30 ℃. In the optimum conditions, residual oil rate in pressing cakes of perilla seeds and peanut kernel were respectively 9.82% and 8.21%. On the same optimize obtained pressing condition the same screw oil expeller was used to press, residual oil rate in pressing cakes was negative interrelate with hardness and fragile 0f oil seeds. But hardness and fragile 0f oil seeds were positive interrelate with contents of crude fiber and protein of oil seeds.2.Transmission electron microscope was used to observation of microscopic structure of the cotyledon cells in four oilseeds and the pressing cakes. The oil in the form of lipid body was stored in the gap of endoplasmic reticulum and protein body and aleurone grains of the oil seed cotyledon cell, under the external compression the structure of oil cell was serious deformed and was destructed when presseing. Due to the incompressibility of oil, oil was squeezed and extruded from deformation and breakage of cell structure then gathered, at the same time the soild-liquid separation of cake and oil was implemented.3.In this article, the flaxseed、rapeseed、perilla seed、peanut kernel and four kinds of pressing cake under the suitable conditions were pressed were used as the raw material to study on the change of contents of crude protein、NSI and composition of amino acid.Because the cake was come out with the temperature of less than 80℃, the nitrogen solubility index(NSI) of pressing cakes of perilla seeds and peanut kernel were rised to raw material(NSI from 31.19% was rised to 36.04%, from32.98% was rised to 36.58%,from 68.72% was rised to 78.07%,from 32.71% was rised to 36.03%) the crude protein was not denatured. Four kinds of raw materials are rich in amino acids, the total contents of amino acid are 17.29mg/100 g in rapeseed, the total contents of amino acid are 15.16 mg/100 g in flax seed, the total contents of amino acid are 17.06 mg/100 g in perilla seed, the total contents of amino acid are 20.83 mg/100 g in peanut kernel. The four kinds of oilseeds under the suitable conditions were pressed, the total contents of amino acid are 25.41 mg/100 g in rapeseed, the total contents of amino acid are 24.13 mg/100 g in flax seed, the total contents of amino acid are 27.89 mg/100 g in perilla seed, the total contents of amino acid are 34.74 mg/100 g in peanut kernel. The contents of amino acids in four kings of pressing cake are obviously higher than these of four kinds of raw materials. Thereinto, except content of methonine in perilla cake was slightly debased( from 0.30 mg/100 mg was deseased to 0.28mg/100mg), contents of methonine in other pressing cakes were rised. Contents of lysine of four kinds of pressing cakes are obviousely riser than oil seeds. This suggests that squeezing process, as the oil was pressed from the oil seeds, contents of protein of pressing cake were rised, because of low pressed temperature 、 short heating time, protein of pressed cake was not degeneration or slight degeneration, This is created favorable conditions for development and utilization of protein resource of pressed cake. Thereinto, except content of methonine in perilla cake was slightly debased( from 0.30 mg/100 mg was deseased to 0.28mg/100mg), contents of methonine in other pressing cakes were rised. Contents of lysine of four kinds of pressing cakes are obviousely riser than oil seeds. This suggests that squeezing process, as the oil was pressed from the oil seeds, contents of protein of pressing cake were rised, because of low pressed temperature、short heating time, protein of pressed cake was not degeneration or slight degeneration, This is created favorable conditions for development and utilization of protein resource of pressed cake.4. The four kinds of oilseeds throng careful selection 、 cleanning and edulcoration, under the suitable conditions were pressed, then the quality index and hygienic index of the pressed oil and the hydrated degumming oil were analysed. The results showed: four pressed oil by hydrated degumming rapeseed oil, perillaseed oil exceeded to the four stage oil or closed to three stage oil of the national standard(refer to GB1536-2004); flaxseed oil meet the pressed first grade oil national standard(GB/T8235-2008),peanut oil was in accordance with a pressed oil nationalstandard(GB/T1534-2003).Hygiengic index: heavy metal arsenic, lead content, aflatoxin, benzopyrene all did not exceed the standard(GB2716-2005); pesticide residue were not detected. In addition, the composition of fatty acid of four kinds of pressed oil, phytosterol and vitamin E were detected and analyzed, the results showed: four kinds of pressed oil were rich in unsaturated fatty acids, alpha linolenic acid was rich in、perilla seed oil and flaxseed oil; Phytosterol and vitamin E content of four kinds of pressed oil were decreased after hydrated degumming. This suggests: as long as the raw material was carefully seleceted throng cleaned and edulcorated, then pressed and moderately refined crude oil, quality of oil was reached to national standards and meted hygienic standard of edible vegetable oil(GB2716-2005). So, the pressed oil was this made are safe.