Thermal characteristics of a water soluble extract obtained from pomegranate skin

Developing a state diagram for determining stability

Amani Al-Rawahi*, Mohammad Shafiur Rahman, Mostafa Waly, Gilles J. Guillemin

*Corresponding author for this work

Research output: Contribution to journalArticle

12 Citations (Scopus)


A water-soluble extract of pomegranate peel was prepared and freeze-dried to measure its thermal characteristics as a function of moisture and temperature. Moisture contents of the freeze-dried extracts varied from 0.018 to 0.950g/g sample. A state diagram of the extract was developed by measuring the freezing curve, glass transition line and ultimate maximal-freeze-concentration conditions. The freezing point decreased with increasing solids; whereas glass transition decreased as solid levels decreased. The freezing point and glass transition were modelled using Chen's model based on the Clausius-Clapeyron equation, and Gordon-Taylor equation, respectively. The ultimate maximal-freeze-concentration conditions were (Tm')u equal to -32.2°C and (Tg‴)u equal to -33.4°C, and the characteristic solids content, Xs' was 0.52g/g sample (i.e. un-freezable water, Xw'=0.48g/g sample), respectively. Similarly the value of Tg' (i.e. vertical line passing through (Tm')u and crossing the glass transition line) was determined as -76.0°C.

Original languageEnglish
Pages (from-to)198-204
Number of pages7
JournalIndustrial Crops and Products
Publication statusPublished - Jul 2013
Externally publishedYes

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