Optimization of extraction of microcrystalline cellulose from orange peel waste using response surface methodology

Abstract

This study investigated the optimum processing conditions for obtaining the maximum yield of microcrystalline cellulose (MCC) powder from orange peel waste (OPW) by use of response surface methodology (RSM). Central composite design (CCD) was used to evaluate the optimum process conditions for producing MCC from alpha cellulose obtained from OPW. The factors investigated for getting the optimum conditions were temperature (90 – 110^o C) and hydrolysis time (10 - 25 min). Both factors were found to have significant effect on the yield of MCC and the model that described the process had coefficient of determination  R²) of 0.9808. The  adjusted R² was checked to ensure model adequacy, which gave a value of 0.9695. Optimum process conditions o for hydrolysis as ascertained by RSM were 100.53^o C and 16.28 min. Characterization of the optimized MCC obtained showed that it had an angle of repose of 50.08^o , pH of 6.7, moisture content of 6% bulk and true density of 0.346 and 1.48 g/ml respectively indicating a similar degree of crystallinity as that of commercial grade microcrystalline cellulose (Avicel PH101). It was however found to be composed of aggregated fibres at magnifications of 1000 X using a scanning electron microscopy (SEM) as opposed to the non-aggregated fibres of Avicel PH101 at same magnification.

Keywords: Microcrystalline cellulose, Orange peel waste, Alpha cellulose, Response surface methodology