Enzymatic modification to improve the water-absorbing and gelling properties of psyllium

Psyllium husks were treated with a commercial food-grade polysaccharidase mixture, under solid-state reaction conditions, to improve water-absorbing and gelling properties. The modified psyllium preparations were analyzed and compared to the original psyllium and the control, treated with no enzyme under the same reaction conditions, for their water-absorbing ability, gelling properties, fibre contents, and surface structures. The water-absorbing ability was determined by a gravimetric method, while the gelling property of the modified psyllium was measured using a texture analyzer. The results showed that the solid-state enzymatic modification was able to significantly reduce both water-absorbing and gelling abilities of psyllium. Compared to the control, reductions of 49% in water-absorbing ability, 71% in gel hardness, and 35% in gel adhesiveness were observed for the novel psyllium preparation that was treated with the enzyme mixture at a level of 36 units/g psyllium. The surface structure of the modified psyllium was examined using scanning electron microscopy (SEM). The SEM results showed that the enzymatic modification decreased the total surface area. This may contribute to the reduced water-absorbing ability of the modified psyllium. This study demonstrated the potential of preparing novel psyllium preparations, using a solid-state enzymatic method, for commercial food applications.