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Effects of Thermomechanical Extrusion and Particle Size Reduction on Bioconversion Rate of Corn Fiber for Ethanol Production
Author(s) -
Lin Myat,
Ryu GiHyung
Publication year - 2014
Publication title -
cereal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.558
H-Index - 100
eISSN - 1943-3638
pISSN - 0009-0352
DOI - 10.1094/cchem-05-13-0105-r
Subject(s) - extrusion , chemistry , fiber , bioconversion , particle size , ethanol , ethanol fuel , fermentation , starch , food science , biochemistry , composite material , materials science , organic chemistry
The objective of this research was to evaluate the effect of thermomechanical extrusion and particle size (PS) reduction on the bioconversion rate of corn fiber for ethanol production. Extrusion was conducted at a screw speed of 300 rpm, feed rate of 120 g/min, feed moisture content of 30%, melt temperature of 140°C, and die diameter of 3 mm. Raw and extruded corn fiber were separated into three different PSs (1 > PS ≥ 0.5, 0.5 > PS ≥ 0.3, and 0.3 > PS ≥ 0.15 mm) with a wire sieve. Extrusion pretreatment and PS reduction resulted in a significant ( P < 0.05) difference in physical properties and color values of extruded corn fiber as a result of accelerated degradation of corn fiber structure. Significant increase in water solubility index of extruded corn fiber at 0.3 > PS ≥ 0.15 mm was an indication of high degradation of starch during extrusion for higher release of polysaccharides. Moreover, extruded corn fiber at PS reduction 0.3 > PS ≥ 0.15 mm also significantly increased ( P < 0.05) ethanol yield (69.11 g/L) and conversion (68.18%) by increasing protein digestibility and free amino nitrogen, which are essential for higher fermentation efficiency.