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Effects of feed moisture and extruder screw speed and temperature on physical characteristics and antioxidant activity of extruded proso millet ( P anicum miliaceum ) flour
Author(s) -
Gulati Paridhi,
Weier Steven A.,
Santra Dipak,
Subbiah Jeyamkondan,
Rose Devin J.
Publication year - 2016
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/ijfs.12974
Subject(s) - expansion ratio , extrusion , moisture , plastics extrusion , absorption of water , antioxidant , materials science , composite material , food science , solubility , chemistry , biochemistry , organic chemistry
Summary The objective of this work was to determine the impact of extrusion variables [moisture (17–25%), screw speed (170–250 r.p.m.) and temperature (90–150 °C)] on the physical properties and antioxidant activity of proso millet extrudates. Extrusion variables were adjusted using an inscribed central composite rotatable design. Response variables were bulk density ( BD ), radial expansion ratio, water absorption index, water solubility index, hardness, colour ( L *, a *, b *) and antioxidant activity. Moisture and screw speed were the most influential variables affecting millet extrusion: their linear, quadratic and interaction terms accounted for more than 50% of the variability in all responses except for b *. Expansion was greatest at severe conditions of low moisture and high screw speed. These conditions were also consistent with the highest antioxidant activity. This study demonstrated that high expansion and antioxidant activity can be obtained by extruding proso millet under low moisture and high screw speed conditions.