| Summary: | 碩士 === 國立中興大學 === 農業機械工程學系 === 82 === Rice flour was used to study the effects of process
variables on physical properties in single-screw
extrusionystem.The response surface methodology with rotable
design was introduced in this research.The process variables
were barrel temperature, screw speed , and additives, and
five levels were designed for each variable.The physcial
properties of extrudatesuch as moisture content, specific
volume,shear force ,expansion ratio and color changes were
investigated. Experimental results showed that: (1) The
moisture content of extrudates increased with increasing its
sugar content,but decreased with increasing its salt content.
(2) The specific volume of extrudates was maximum at
theonditions of screw speed at 560 rpm and 1% salt content ,or
120℃ barrel temperature and 2% salt content. (3) The expansion
ratio increased with increasing barrelemperature and screw
speed.The maximum expansion ratio occurred at 320 rpm screw
speed with both 3% sugar and 2% salt content. (4) The minimum
whiteness index and maximum color difference and b-value
occurred at 320 rpm screw speed and 2% salt content.
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