Impact of Heat Treatment on Spray Dried Gum Arabic Powder and its Effects on Physico-chemical Properties of its Solution and its Emulsion

Abstract

The objective of this study is to investigate the effect of heat treatment on raw Acacia gums and its implications on the physico-chemical prosperities on gum solution viscosity and the stability of their emulsion. Sample of Acacia gums namely Acacia senegal var senegal and Acacia seyal var seyal , were heated at 150°C for different time intervals (17, 48 and 72 hours) in an oven. The physic- chemical prosperities of the heat- treated gum samples were examined where the ash content, pH, specific optical rotation and viscosity of their solution were obtained, following AOAC standard methods.The results revealed that ash content average for Acacia senegal and Acacia seyal 2.5 and 2.1 respectively and pH of its between 4.4 to 4.6 .the samples subjected to heat treatment remained unaltered compared to the control sample .The specific optical rotation and viscosity of solution of heat treated samples showed very significant changes. The optical rotation for all samples differs in their value ,the value in Acacia senegal heat treated for17.48and72 hours equal -26.77,-12.50 and -10.00(degreemlg-1 dm-1 ) respectively , the Optical rotation value in Acacia seyal heat treated for17.48and72 hours equal -+317.5,+239 and +314.5(degreemlg-1 dm-1 ) respectively. but not in the direction of rotation. The increase in solution viscosity was noticeably high for samples of Acacia senegal heated for 48 hours viscosity reach 4731%compared to the control in the value and its order of magnitude. The emulsifying index for the control and heat-treated samples follow the well establish stability characteristics of the two types of gum, where Acacia senegal shows high stability compared to Acacia seyal. The heat treatment for 72hours had improved the stability of Acacia senegal gum slightly compared to the control sample. While heat treatment for 17 hours improved the stability of Acacia seyal gum in comparison to the control sample.