Effects Of Infrared Roasting Treatment On Quality And Storage Stability Of Wheat Germ

The changes in chroma and microstructure of fresh, heat drying and infrared roastingtreated wheat germ were analyzed before and after treatment. Meanwhile, their influences onthe basic ingredients, protein (the content of the component), fat (acid value, peroxide value,malondialdehyde and fatty acid) and enzyme activity (lipase and lipoxygenase) of wheat germwere analyzed. Moreover, the changes in protein, fat and enzyme of infrared baking wheatgerm during30℃and40℃storage were analyzed systematically. The conclusions are asfollowing：(1) After infrared roasting treatment, the brightness, redness and greenness, yellownessand blueness, total color difference of wheat germ were75.43%,1.93%,20.40%and28.85%,respectively. The starch granule of infrared roasting treated wheat germ exhibited a smoothsurface and a clear outline, with a slight deformation and a slightly sticky with protein matrix.The protein network structures were clear and close. Compared with the heat drying, infraredroasting treatment could significantly decrease the brightness, redness and greenness of wheatgerm, while significantly increase the yellowness and blueness, total color difference.Meanwhile, the infrared roasting treated wheat germ showed a more gloden color andmaintained a more original microstructure of the starch granule and protein.(2) Compared with the heat drying, infrared roasting treatment could reduce the moisture,fat, albumin and globulin content of wheat germ, while increase the crude protein, gluten andresidue protein content of the wheat germ.After infrared roasting, the acid value of wheat germ was8.14mg/g, which was lowerthan the fresh and heat drying treated wheat germ. The peroxide value was1.50meq/kg,which was higher than the fresh and heat drying treated wheat germ. The malondialdehydecontent, lipase and lipoxygenase activity were significantly lower than fresh wheat germ andhigher than the heat drying wheat germ.The total unsaturated fatty acids content wheat germ had no change after infraredroasting, and maintained at81.6%. The stearic acid, oleic acid and linoleic acid content inwheat germ all decreased by0.1%.(3) With the extension of storage time, the protein components of infrared baking treatedwheat germ was fluctuat. After75d storage, the cytoplasmic protein content in infraredroasting treated wheat germ was lower than the heat drying treatment, while its storageprotein content was higher compared with heat dried germ. Storage temperature had a certaininfluence on protein components in infrared roasting wheat germ. During storage, the acid value of infrared roasting wheat was first increased and thendecreased, peroxide value decreased first and then increased, malondialdehyde content wasfluctuated, The lipase activity increased all the time., lipoxygenase activity showed agradually decrease trend. Compared with heat drying treatment, infrared roasting treatedwheat germ was associated with a lower acid value and a higher the peroxide value,malondialdehyde content, lipase and lipoxygenase activity. All of the the acid value, lipaseand lipoxygenase activity in infrared roasting treated wheat germ which stored at40℃werehigher than storaed at30℃, which means that the storage temperature has a certain influenceon peroxide value and malondialdehyde content.After75day’ s storage, the palmitic acid, stearic acid and oleic acid content in infraredroasting treated wheat germ were increased, while the linoleic acid and linolenic acid contentwere decreased. Storage temperature had a certain impact on infrared roasting wheat germ’sfatty acid composition.The infrared roasting treated could maintain the quality of wheat germ and it also couldbe effective in improving the storage stability of wheat germ.