| Summary: | 碩士 === 輔仁大學 === 食品營養學系 === 82 === Physical-chemical changes in 2 cultivars guava (cv.Chung-sun &
cv.Bai-ba) during periods of development, maturation and
ripening were investigated. Effect of heat processing in guava
puree also studied. During development and maturation
chlorophyll content of peel decreased, sugars content (
fructose, glucose, sucrose), total soluble solids, ascorbic
acid, Brix-acid ratio increased and titratable acidity,
nonvolatile organic acids, tannin, formol nitrogen decreased.
Pectic substances changed during development and maturation.
Water-soluble pectin increased and NaOH soluble pectin
decreased. 47 components of volatile were identified, and
hydrocarbones predominant. Hydrocarbons, carbonyls decrease and
esters increased during development. Alcohols decreased during
maturation. Post-harvest changes in guava fruit were not all
the same as maturation. During storage sugars content slightly
decreased, total soluble solids, ascorbic acid and Brix-acid
ratio increased. Tannins and formol nitrogen changed slightly.
Changes of pectic substances during storage were similar to
changes during ripening. Water-soluble pectin increased and
NaOH soluble decreased. Volatile content increased then
decreased during storage. Esters content remarkably increased.
Total soluble solid, Brix-acid ratio, ascorbic acid and esters
content of post-harvest guava were higher than yellow soft
guava harvested from tree. Guava fruit during 3 day''s ripening
maintained good quality to be processed. After heating at 95
℃, 45sec, Hunter L, a, b of guava puree increased and formol
value lost. Effect of heat processing on viscosity in 2
cultivar was different. The viscosity of cv.Chung-sun decreased
and of cv.Bai-ba increased after heat processing. NaOH soluble
pectin decreased. Water-soluble pectin of cv.Chung-sun
decreased and of cv.Bai-ba increased. Volatile content,
especially carbonyls, lost after heat processing.
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