Moisture Adsorption Properties of Black and Green Tea and Heat of Sorption (Turkish with English Abstract)

Abstract

Moisture adsorption curves of the green and black teas were determined by using saturated salt solution ranged from 0.1-0.9 water activity values with standard gravimetric methods at 15 and 25 °C. GAB, BET, Oswin, Kuhn, Filonenko-Chuprin, Cubic, Peleg and Halsey models used for expressing the moisture adsorption curves of green and black teas. It has been found that GAB model has higher regression coefficient (R2), lower RMSE % and SSE values compared to other mathematical models. Water activity (aw) values of black and green teas have been found as 0.3619 and 0.4659 respectively. Heat of sorption of black and green tea varied between 12.96-4.762 kj/mole and 12.18-4.946 kj/mole respectively at moisture levels varying between 4-6 g water/100 g dry basis.

Keywords

• Aw, GAB, heat of sorption, isotherm, black and green tea, regression

Siyah ve Yeşil Çayın Nem Adsorpsiyon Özellikleri ve Sorpsiyon Isısı

Abstract

Siyah ve yeşil çayın 15 ve 25 °C’de nem adsorpsiyon eğrileri 0.1-0.9 arasında değişen su aktivite değerlerindeki tuz çözeltileri ile standart gravimetrik yöntemler kullanılarak belirlenmiştir. Yeşil ve siyah çayın nem adsoprsiyon eğrilerinin ifade edilmesinde GAB, BET, Oswin, Kuhn, Filonenko-Chuprin, Kübik, Peleg ve Halsey modelleri kullanılmıştır. Siyah ve yeşil çay numunelerinin nem adsorpsiyon eğrilerininin belirlenmesinde GAB modelinin diğer modellere oranla, yüksek regresyon sabiti (R2) ve düşük % RMSE ve SSE değerlerine sahip olduğu belirlenmiştir. Siyah ve yeşil çay örneklerinin aw değerlerinin 0.3619 ve 0.4659 olduğu belirlenmiştir. Siyah ve yeşil çay numunelerinin 4-6 g su/100 g k.m değerlerinde sorpsiyon ısılarının sırasıyla 12.96-4.762 kj/mol ve 12.18-4.946 kj/mol arasında deşişim gösterdiği belirlenmiştir.

Keywords

• Aw, GAB, izoterm, siyah ve yeşil çay, regresyon, sorpsiyon ısısı

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