Grinding characteristics and hydration properties of coconut residue: a source of dietary fiber

Abstract

After the extraction of coconut milk from the disintegrated coconut grating, the spent grating (residue) can be utilized as dietary fiber. The fiber was ground in a disc mill and grinding characteristics were evaluated by calculating work index (0.206 kW h/kg) as well as Bond’s (0.065 kW h/kg), Kick’s (0.047 kW h/kg) and Rittinger’s (0.022 kW h/kg) constants. The reduction in the particle size from 1127 to 550 μm resulted in increased hydration properties (water holding, water retention, swelling capacity), which may be due to increase in theoretical surface area and total pore volume as well as structural modification. Beyond 550 μm, the hydration properties were found to decrease with decrease in particle size during grinding. The fat absorption capacity was found to increase with decrease in particle size. The study of microstructures revealed that the grinding operation resulted in rupture of honey comb physical structure fiber matrix and resulting in flat ribbon type structure, thereby providing increased surface area for water and fat absorption.