| Summary: | 碩士 === 東海大學 === 食品科學系 === 83 === The study was focused on investigating optimum conditions for
utilizing chitosan in deacidification, clarification and
antisepsis of grapefruit juice, also discussing effects of
these treatments on the change in components and the sensory
evaluation of the treated products. As a result, chitosan that
had 90% deacylation showed a superior deacidified degree. A
batch-type deacidification carried out by adding the chitosan
into grapefruit juice at a concentration of 0.015 g/mL and
stirring under room temperature for 30~60 min, gave the
deacidified process was removed about titratable acidity
52.6%. On the other hand, a continuos-type deacidification
operated by pumping the original grapefruit juice with a flow
rate of 5 mL/min through a glass-column reactor(2×18 cm)
containing 5 g(dw) chitosan gave the total effluent having the
ratio of Brix/acid about 13.5 after operation of 80 min. The
chitosan had excellent properties of regeneration and reuse. As
the clarification was carried out at a concentration about 90
ppm under stirring at room temperature, the urbidity of the
clarified juice was 0.49 NTU. About the microbial growth in
juice, the clarification treated with a chitosan solution
largely decreased the growth of total aerobic counts from 1720
to 390 CFU/mL. The antimicrobial effect was good in the case
of adding chitosan solution into the clarified juice at a
concentration of 100 ppm, the total aerobic acid count
decreased to about 100 CFU/mL. In comparation to the original
juice, the chitosan treated juice decrease 94% of total aerobic
counts. It also showed inhibition of yeast and mold growth
during 30 day''s storage at 6℃.
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