Water adsorption isotherms and phase transitions of spray-dried chickpea beverage

Chickpea hydrolysate powders were obtained by spray-drying (70 and 60 degrees C as outlet and 180 degrees C inlet air temperatures), using inulin and maltodextrin as adjuvants (12 or 25 g/100 g solids). No effects of the variables studied were observed on solubility (88-93 g/100 g solids) and final moisture (3.50-6.15 g/100 g db). Yields were 49.44-61.24 and 44.53-51.55% at 70 degrees and 60 degrees C respectively. Moisture adsorption isotherms (25 degrees, 35 degrees and 45 degrees C) were obtained by dynamic dew point method and modeled with GAB and BET equations. BET monolayer moisture values (5.53-9.66 g/100 g db), were slightly different and higher than those obtained for the GAB model. Critical values of water activity (awc) and critical moisture (Mc), related with phase transitions, were determined using the second derived from moisture change with respect to water activity (Sovitsky-Golay 2nd derivate). At 25 degrees C the highest awc and Mc values, 0.515 and 0.535, and 8.5 and 9.35 g/100 g db occur for products dried at 60 degrees C and with the lowest level of both adjuvants, while the product without adjuvant has an awc and Mc f 0.466 and 7.46 g/100 g db. The increase in awc and Mc, due to the presence of the inulin and maltodextrin reflects their protective effect. According to these results spray-drying (Tout = 60 degrees C) could be used to generate a stable dehydrated hydrolysate chickpea beverage basis using 12.5 g/100 g db of the adjuvants evaluated.

Automated summary

In this study, chickpea hydrolysate powders were obtained by spray-drying, and the effects of different variables on the properties of the powders were investigated. The results showed that the addition of inulin and maltodextrin improved the stability and protective effect of the hydrolysate, providing a new method for the production of stable dehydrated beverage bases.