Processing of gum arabic and some new opportunities

Gum arabic from Acacia senegal var. kerensis was processed following two approaches: heating the gum solution and using enzyme biotechnology. Studies on heat processing were carried out at 100 degrees C (i.e. simulating the conventional industrial method) and at 65 degrees C. Experiments on enzyme biotechnology were carried out using three enzymes; a Pronase, Viscozyme and a beta-D-galactosidase. In both experiments the solutions were allowed to stand for 96 h with samples of 100 ml being removed every 3, 6, 12, 24 and 48 h. Results of heat processing showed that heating gum solution at 100 degrees C for more than 6 h caused significant degradation of the protein component and subsequent loss of emulsification properties, though a reduction in viscosity and gelling to desired levels was achieved. Heating at 65 degrees C achieved reduction in gelling within 24 h without drastic loss in emulsification functionality. Thus three enzymes caused loss in viscosity and gelling but with different implications for the other gum properties. Pronase degraded the gum to 16 ml/g within 12 h but there was loss in protein and emulsification properties. It is therefore not suitable for processing gum where emulsification and stabilisation are important properties. Both viscozyme and beta-D-galactosidase attained reduction in viscosity and gelling to levels desired for industrial uses within 24 h. The former enzyme however, caused some degradation of the protein component giving rise to unstable emulsions; the amino acids released selectively were arginine, histidine, hydroxyproline, leucine, serine and threonine and three was also release of neutral sugars, particularly rhamnose. The effect of beta-D-galactosidase was to increase the overall protein content and subsequent emulsification properties. These of moderate heating and enzymes in future processing technology is discussed in the light of this work.