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Moisture desorption isotherms and glass transition temperatures of osmo-dehydrated apple and pear

Paper ID Volume ID Publish Year Pages File Format Full-Text
19291 43057 2013 8 PDF Available
Title
Moisture desorption isotherms and glass transition temperatures of osmo-dehydrated apple and pear
Abstract

The aim of this work was to evaluate osmo-dehydrated pear and apple stability on the basis of combined data of moisture desorption isotherms and glass transition temperatures (Tg) investigated in the temperature range of 30–60 °C. Parallelipedic pieces of pears and apples were osmo-dehydrated at 30 °C in sucrose syrups at 70% during 65 min. To study their hygroscopic properties behavior, the osmo-dehydrated fruits were stored in static desiccators at 30, 45 and 60 °C, and relative humidities ranging from 6 to 80%. The GAB model satisfactory described the relationship between the water activity (aw) and water content (X) of osmo-dehydrated fruits (r2 ≥ 0.994). Differential scanning calorimetry was used to measure Tg of osmo-dehydrated fruits conditioned at various water activities. A strong plasticizing effect of water on Tg was found with a large reduction of Tg when the water content increased. The dependence of Tg on water activity data was satisfactory correlated by the Roos model (0.993 ≤ r2 ≤ 0.999). Whereas the Tg ∼ Xw was adequately described by Gordon and Taylor model (0.898 ≤ r ≤ 0.990). The changes of Tg ∼ aw and Tg ∼ Xw were established and the critical values of water contents were determined for the investigated range of temperature.

► Desorption isotherms of osmo-dehydrated apples and pears at 30 °C, 45 °C and 60 °C. ► Sorption isotherms decreased with increasing temperature, exhibited type III behavior. ► Thermal transitions by using differential scanning calorimetry to develop state diagram for the studied fruits. ► Desorption isotherm to compare stability criterion with the concept of glass transition.

Keywords
Desorption isotherm; Apple; Pear; Osmotic dehydration; Critical water activity; Glass transition temperature
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Moisture desorption isotherms and glass transition temperatures of osmo-dehydrated apple and pear
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Publisher
Database: Elsevier - ScienceDirect
Journal: Food and Bioproducts Processing - Volume 91, Issue 2, April 2013, Pages 121–128
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us