Oral Presentation Joint Annual Scientific Meeting of the Nutrition Society of NZ and the Nutrition Society of Australia

Nutritional role of cellulose beyond faecal bulking (309)

Sushil Dhital 1 , Mike Gidley 1
  1. ARC Centre of Excellence in Plant Cell Walls, Centre for Nutrition and Food Sciences, The University of Queensland, Brisbane, QLD, Australia

Background/Aims: Cellulosic materials are important sources of dietary fibre and are abundant in whole grains, legumes, fruits and vegetables. Apart from its nutritional importance as a bulking agent, we report additional roles of cellulose in human nutrition by limiting digestive enzyme action either by binding of enzymes on cellulose surfaces or providing a physical barrier towards the hydrolysis of entrapped macronutrients.

Methods: (i) The kinetics of inhibition of alpha amylase activity against maize starch was determined varying cellulose concentration. (ii) Cotyledon cells from legumes were isolated without using solvents, acids or bases. The diffusion of enzyme inside the cell was monitored using fluorescence labelled alpha-amylase.

Results: Kinetic analyses of alpha amylase hydrolysing maize starch in the presence of cellulose as an inhibitor using Dixon and Direct Linear plots showed marked inhibition of mixed type. The dissociation constant of the enzyme/cellulose complex was found to be 3 mg/mL. In isolated legume cells, fluorescent labelled enzymes accumulated at the outer periphery of cells and were absent inside the cells, suggesting both a binding and barrier role for cellulose. Upon removal of cellulosic physical barrier, e.g. by grinding, the rate of hydrolysis of starch in cells of legumes increased by almost 20 times.  

Conclusions:   The study suggests that cellulosic materials have the potential to reduce the glycaemic responses form starchy foods either by inhibiting enzyme activity through binding or providing the physical barrier limiting the access of substrate to enzymes in plant-derived foods

Funding source(s): ARC, UQ