Moisture sorption isotherm, isosteric heat and adsorption surface area of whole chia seeds

• Published in: Food science & technology 2020-02, Vol.119, p.108859, Article 108859
• Main Author: Arslan-Tontul, Sultan
• Format: Article
• Language: English
• Subjects: Isosteric heat; Moisture content; Oilseed; Sorption isotherm; Water activity
• ISSN: 0023-6438; 1096-1127
• DOI: 10.1016/j.lwt.2019.108859

This study aimed to evaluate moisture sorption isotherm of whole chia seed. The equilibrium moisture content (EMC) of seeds were detected by saturated salt solutions which have the water activity (aw) range of 0.2–0.9. The isosteric sorption heat was calculated by the Clausius-Clapeyron equation using three different sorption temperatures (15 °C, 25 °C and 35 °C). The adsorption surface area of seeds was also calculated by monolayer moisture content obtained from BET and GAB equation. The EMC content of seeds had an increasing trend and determined as 18–20 g H2O/100 g solid at the highest aw level. The whole chia seeds became less hygroscopic with the rising sorption temperatures at constant aw. The moisture sorption isotherm was determined as Type II. The monolayer moisture content was determined as 2.39–2.91 g H2O/100 g solid. BET and Peleg were the best-fitted models. The isosteric and net isosteric heat were 77.74 and 34.74 kJ/mol at lowest moisture content, respectively. Additionally, the adsorption surface area changed between 95.31 and 102.72 m2/g. •BET and Peleg model gave the best fit to sorption data.•The monolayer moisture content of seeds was calculated as 2.39–2.91 g H2O/100 g.•The isosteric heat decreased from 78 to 45 kJ/mol by increasing moisture content.•The adsorption surface area decreased by increasing sorption temperature.