Moisture sorption isotherms and storage study of spray dried tamarind pulp powder

Abstract

Moisture adsorption isotherms and storage study of spray dried tamarind pulp powder were evaluated in this work. Adsorption isotherms of tamarind pulp powder were determined at four different temperatures (20, 30, 40 and 50°C) using a gravimetric technique. The sorption isotherms were found to be typical type II sigmoid. The experimental data obtained was fitted to several mathematical models viz. two-parameter (BET, Oswin, Smith, Caurie, and Iglesias and Chirife), and three-parameter (GAB) relationships. A non-linear least square regression analysis was used to evaluate the model constants. The GAB followed by Oswin model best fitted the experimental data. Changes in physicochemical properties of tamarind pulp powder were evaluated during storage (at 0, 1, 2, 3, 4, 5 and 6months), using three different packaging materials (low density polyethylene, LDPE; aluminum laminated polyethylene, ALP and glass). Color parameters, moisture content, titratable acidity, bulk density and flowability of the powder varied to different extent during storage, depending on the type of packaging material used. Compared to other packaging materials, powder packed in LDPE showed considerable changes in physicochemical properties during storage. The magnitude of the change in physicochemical properties of the powder measured during storage suggests that glass is best for long term storage of tamarind pulp powder.