| Author | Li, Xiang-yan |
| Call Number | AIT Thesis no. AE-95-13 |
| Subject(s) | Fruit--Drying
|
| Note | A thesis submitted in partial fulfillment of the requirements
for the Degree of Master of Engineering, School of Environment, Resources, and Development |
| Publisher | Asian Institute of Technology |
| Abstract | Experiments were carried out to investigate the effect of vacuum
treatment on osmotic dehydration of pineapple. Two maturity stages sample,
150 and 120 days after flowering used. Two kinds of vacuum operating
test: 1. Osmotic dehydration under vacuum condition and normal pressure test;
2.Vacuum technique operation prior to osmosis process; were done in this
study. The pressure was set at -640 mm Hg and normal pressure and the
temperature was maintained at 50°C. The osmotic solution concentration was
varied from 303 - 703. Drying characteristics for the dehydration of osmosed
and non-osmosed pineapple were determined at drying temperature of 60°C and
70°C. Texture, color, final moisture content and rehydration ratio for the dried
sample were determined.
The results obtained from this study showed that osmotic dehydration
under vacuum condition has a significant effect on water transfer rate and
gives good quality of dehydrated fruit product. No significant difference was
found in the sugar gain under vacuum and normal pressure treatment.
The vacuum operating parameters included vacuum maintained time and
vacuum release time during the process. Using this technique prior to osmosis
process gave a higher sugar gain value by 3 - 5 gram than the conventional
method, but applying longer vacuum maintained time and longer vacuum release
time showed no significant influence on sugar gain. Increasing vacuum release
time caused an increases in weight reduction, but increase in sugar gain was
not significant.
Vacuum osmosed sample has lower drying rate during the secondary
drying process. The final products of vacuum sample have attractive yellow
color and look trans parent. The rehydration ratio of vacuum sample was lower
than non- vacuum osmosed sample and fresh sample. |
| Year | 1995 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Athapol Noomhorm
|
| Examination Committee(s) | Jindal, V. K.;Vincent, J. C.
|
| Scholarship Donor(s) | Government of Denmark
|
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1995 |