Study On Wheat Germ Pretreatment And Wheat Germ Oil Refining Technology

Wheat germ(WG)and crude wheat germ oil(WGO)were employed to study effects of five different pretreatments on the nonphospholipids(NHP)content,physicalchemical characters,vitamin E and fatty acid of wheat germ oil as well as impact of refining on wheat germ oil quality.Results are as follows:(1)Optimization of technology to reduce NHP content in WGO using microwave pretreatmentEffect of initial moisture content of WG on the NHP content of oil extracted from microwave pretreated WG was greater than that of microwave power and time.Also,extremely significant(P<0.01)and significant(P<0.05)difference were observed regarding impact of WG's initial moisture content and microwave time.While microwave power influenced the NHP content insignificantly(P > 0.05).Optimized microwave technology using orthogonal experiment was to microwave WG with initial moisture content 26.00% for3 minutes under 480 W.And WGO containing 0.087mg/g was obtained under the optimized microwave technology.(2)Effect of five kinds of pretreatment on quality of WGOWG toasted 150 minuetes under 135?or hot-air dried 90 minutes had a higher oil yield and NHP content was lower in WGO extracted from WG pretreated with methods.Enzymes e.g phospholipids and lipoxygenase were effectively deactived by atomospheric steaming10 minutes and high-pressure steaming 30 minutes,which resulted in a obvious decrease in content of phospholipids an NHP.Compared with other fours pretreatments,microwave WG not only could improve the oil yield and diminish NHP content but also increased the phospholipids.Both atomospheric steaming and microwave could better preserve tocopherol of WGO.Different pretreatments did not influence the fatty acid composition of WGO.Greatest extent of pasting and denaturation in starch and protein were observed in atmospheric steamed and high-pressure steamed WG.And starch particles in toasted and hot-air dried WG were relatively intact.(3)Impact of refining on the quality of WGORefined WGO as achieved by phospholipid aided water degumming with the 0.5%(w/w)phosphoric acid and water of three times of phospholipids content at 60?for 30 minutes,deacidification at 60?with an alkalinity of 8.00%(w/w)and excess alkali of 0.22%(w/w)for 40 min,bleaching using 5.98%(w/w)the mixture of white clay and activated carbon(18:1)at 80? for 25 min,deordorization at 220? for 10 min could remove the ordor completely while maintain the most VE.Deacdification effectively reduced the acid value and phoospholipids content to0.38mgKOH/g and 160mg/kg and bleaching alleviated the color of wheat germ oil.Refining had little effect on the fatty acid composition and total fatty acid content.The refining caused a vitamin E loss of up to 51.75% indicating that the deacidification and deordoration process had great influence on the quality of wheat germ oil.