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Changes in Water Absorption and Swollen Volume in Extruded Alkaline Peroxide Pretreated Rice Hulls
Author(s) -
Larrea M. A.,
Grossmann M. V. E.,
Beléia A. P.,
Tavares D. Q.
Publication year - 1997
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.1997.74.2.98
Subject(s) - chemistry , extrusion , absorption of water , hydrogen peroxide , volume (thermodynamics) , rice hulls , plastics extrusion , absorption (acoustics) , moisture , fiber , solvent , chromatography , composite material , organic chemistry , materials science , physics , quantum mechanics
Rice hulls were pretreated with an alkaline (pH 11.5) solution of hydrogen peroxide (1%) and then extruded. Pretreatment of rice hulls (4% db) at 50°C for 12 hr promoted 94.4% silica reduction, caused lignin solubilization and increased water absorption index (54%) and swollen volume (44%). The effects of temperature (125, 175, and 225°C), moisture content (25, 30, and 35%) and screw speed (120, 140, and 160 rpm) on water absorption and swollen volume of rice hulls fiber were evaluated after extrusion in a single‐screw extruder. Operational conditions that produced the most modified product with regard to the functional properties were: 125°C, 35% moisture, and 120 rpm. Extruded fiber had a water absorption index 95% higher and swollen volume 138% higher than the unprocessed material. Microscopic examination showed a slight effect on the hulls epidermis after pretreatment, while extrusion promoted cellular structure disruption.