Study On Oils Extraction And Cyanogenic Glycosides Elimination With Two-liquid-phase System And Resulting Protein Characterization Of Flaxseed

Flaxseed has received increasing attention as a major source of oilseed and a high quality protein, as well as abundant functional factors containingα-linolenoic acid and lignan. However, the applications of flaxseed in food industry and feedstuff is quantificationally limited due to the existence of cyanogenic glycoside and other anti-nutritional factors. The objective of this study is to develop two-liquid-phase technology of hexane-ethanol-water on simultaneous extraction of oils and cyanogenic glycosides from flaxseed to obtain good oils and detoxined flakes, and make a study of protein compositions and functional properties. The main results are as follows.Fatty acids and volatile compounds in flaxseed were separated and identified by GC-MS. 13 fatty acids identified in flaxseed oil consist of 4 saturated fatty acids (12.71 %) and 8 unsaturated fatty acids (87.1 %). The saturated fatty acids are mainly composed of hexadecanoic acid (7.31 %) and octadecanoic acid(5.04 %). The unsaturated fatty acids are mainly composed of linolenoic acid (49.05 %), oleic acid(22.34 %)and linoleic acid(13.73 %). And 38 compounds of volatile oils in flaxseed were identified, mainly including 2-butanone (23.17 %), methylhydrazine (13.75 %), phenylethylene (7.78 %), n-tetradecane (3.05 %), isopropanol (2.61 %), allyl isothiocyanate (2.49 %), hexaldehyde (2.44 %). The volatile compound identified is 90.58 % in volatile oil, and the weight of volatile oil is 1.8 % in flaxseed.Determination method of cyanogenic glycoside was established by modified isonicotine acid-pyrazolone colormetric method with very strong linear relevance (R2=0.9986) and high returns-ratio of additive sample ( from 93.08 % to 95.65 %) as well as small relative standard deviation (less than 5 %). Otherwise, the course of flaxseed oils extracted by hexane has almost no effection on cyanogenic glycoside concentration of flaxseed which was decreased by 43.18 % at 90°C for 1 h. However, the craft of double screw rod extrusion puffs has the obvious removal of cyanogenic glycoside of flaxseed, with 88 % destruction rate of cyanogenic glycoside.Mutual solubility of hexane-ethanol-water system increases along with augmentation of temperature and ethanol concentration which showed balance relations between water content of flaxseed and ethanol concentration of three fractions solvent system in the course of extraction. The corresponding balance relations were as follows: 95 % ethanol concentration in solvents to 7~9 % water content in flaxseed; 90 % ethanol concentration in solvents to 9~11 % water content in flaxseed; 85 % ethanol concentration in solvents to 10~12% water content in flaxseed.