Effects of Moisture Content on Physical Properties of Extruded Cereal Flours
2012
Kim, C.H., Kongju National University, Yesan, Republic of Korea | Tie, Jin, Agricultural College of Yanbian University, Yanji, Jilin, China | Ryu, G.H., Kongju National University, Yesan, Republic of Korea
The effects of moisture content on the physical properties of cereal extrudates were investigated. Cereal flours (rice, wheat, corn, barley, and oat) were extruded at a barrel temperature of 130℃, feed rate of 120 g/min, and various moisture contents (20, 22.5, 25, 27.5, and 30%). Proximate content, expansion index, specific length, bulk density, breaking strength, apparent elastic modulus, water absorption index (WAI), water solubility index (WSI), specific mechanical energy (SME) input, paste viscosity, and color values were analyzed. Expansion ratio of extruded corn flour was higher than that of other extrudates at low moisture content. Bulk density, specific length, and elastic modulus in all cereals decreased with an increase in moisture content. The WAI increased with an increase in moisture content, whereas WSI decreased. SME input of extruded corn flour was higher than those of other cereal flours at lower moisture content, whereas that of oat flour extrudate lower than those of other cereals at higher moisture content. Lightness of extruded rice flour was lighter than those of other cereals while that of extruded barley flour was darker.
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