| Summary: | 碩士 === 國立臺灣大學 === 農業機械工程學系 === 84 === Nowadays the consumer is emphasizing more in produces quality
than quantity. An efficient quality-testing system is necessary
in guaranteeing high quality produces. There are many methods
in detecting quality of agricultural produces, but some fast
and accurate non-destructive methods, such as ultrasonic
technique, are getting popularity in the future. The purposes
of this thesis were to develop a reliable ultrasonic testing
system and to analyze the correlation between ultrasonic
characteristics and physical properties of radish during cold
storage period. The results indicate that wave velocity
decreases with the increase of storage time. At low storage
temperature of 5℃ the changes of wave velocity are negligible.
The packing methods also influence the change of wave velocity
and moisture content of radish. The radish stored in a sealed
packing at low temperature is recommended. The hollow volume
inside a radish is served as an index of quality evaluation.
The hollow volume of a normal radish is about 5%~10%. If the
hollow volume is over 20%, the radish is rejected in the
market. There are significant correlation between wave velocity
and hollow volume, density, and young''s modulus of radish.
During storage, both temperature and storage period have linear
effect on the change of wave velocity. The degree-day (the
product of storage temperature and day) is used as a parameter
in evaluating radish quality. The equation y=0.732+0.04x shows
the relation between degree-day(x) and the change of wave
velocity(y).
|
|---|
