Effect of extrusion on physical and chemical properties and storage stability of corn germ

Abstract Background and objectives Corn germ is a by‐product of corn starch processing, which is rich in nutrients but easy to rancidity. In order to improve the storage stability of corn germ and prevent the metamorphism, raw germ was treated with twin‐screw extruder. Lipase ( LA ) and lipoxygenase ( LOX ) activities, free fatty acid ( FFA ), nutrient composition, microbiology, and microstructure of germ were investigated and the shelf lives were calculated. Findings Extruding doubled the content of SDF, LA activity reduced to 19.42% and LOX activity reduced to 0% at 120°C and 25 Hz. The total bacteria count and mold count of raw germ decreased significantly. FFA of extruded germ increased slower than that of raw germ during storage and the shelf lives were predicted by a mathematical model experiment and it was 13.5 times as raw corn germ while extruded in 25 Hz and 120°C. Conclusions Extrusion stabilization technology did not only keep the nutrients of corn germ, but improve the quality and prolonged the shelf life. Significance and novelty This study could provide an important reference for further research and industrial production of corn germ.