Effect Of Different Pretreatments On Lignans Content Of Flaxseed Oil

A method of determing the lignans content of flaxseed using Ultraviolet-visible spectroscopy under the condition of ultrasonic assisted extraction was established. This study explored the effects of different pretreatments (enzymatic and microwave pretreatments) on oil extraction yield and the lignans content of the oil. Meanwhile, the quality properties and fatty acid profiles of the oils obtained from the different pretreatment methods were investigated.Lignans in flaxseeds is a kind of physiologically substance, which is capable of antioxidant, anti-tumor, prevention of breast cancer and other important functions. The present study was to examine the content of lignans in flaxseed by UV spectrophotometry. The lignans was extracted with methanol under ultrasonic conditions. The absorbance of the sample was measured at 280nm. The UV methods can determin the lignans content in flaxseeds and the average recovery rate was 100.71%. It was concluded that the ultraviolet spectrophotometry method, which had high degree of precision and good reproducibility, was a fast, simple and reliable measuring method for lignans detection in flaxseeds.The univariate tests and response surface methodology were applied to determine the influence factors and optimize the parameters in microwave pretreatment on flaxseed oil. The optimum condition for microwave pretreatment were as follows:microwave pretreatment time 5.6min, raw material moisture content 6.5% and microwave power 130W. After a triplicate verification, the flaxseed oil extraction yield and the lignans content of the oil were 96.02% and 0.71%, respectively.Enzymatic treatment on flaxseed was studied according to the structure of flaxseed and the distribution location of lignans in flaxseed. The influence of seven single enzyme pretreatment (Neutrase 0.8L, Viscozme L, Finizyme W, etc) and complex enzyme (Viscozme L, Pectinex Ultra Clear and Novobate WB) on the lignans content of flaxseed oil was investigated. The research indicated that the effect of formula of Viscozme L and Pectinex Ultra Clear was better. Under the condition that moisture 43%, enzymes/flaxseeds 2%(w/w), mass ratio of Viscozme L and Pectinex Ultra Clear 50:50 (w/w), temperature 46℃, hydrolysis time 91min, the flaxseed oil extraction yield was 95.79%, and the lignans content of the oil is 1.09%.The quality properties and fatty acid profiles of the oils obtained from four different methods (enzymatic pretreatment, microwave pretreatment then extracting oil with acetone, extracting the flaxseed oil with acetone and n-hexane directly) were analysed. There were no significant differences among the quality properties of four different kinds of oils. Enzymatic pretreatment and microwave pretreatment did not affect the fatty acid composition of flaxseed oil. Compared with the lignans content of the flaxseed oil extracted with acetone and n-hexane directly, the flaxseed oil with enzymatic pretreatment had the hightest amount of the lignans,1.01%, followed by the flaxseed oil with microwave pretreatment,0.71%. It can be established that enzymatic and microwave pretreatments can effectively improve the lignans content of flaxseed oil and have little influence on the quality of flaxseed oil.