Extraction and characterization of methylcellulose from pineapple processing industry waste

The study involved the extraction of cellulose from various streams of pineapple processing industry waste (crown, peel, and pomace) using the sodium hypochlorite (NaOCl) bleaching method, followed by the chemical modification of cellulose using dimethyl sulfate. The cellulose yield ranged from 19 to 49%, with the pineapple crown waste providing the highest cellulose yield. The yield of methylcellulose (MC) from cellulose samples ranged from 69 to 73%, with the MC from crown cellulose exhibiting the highest degree of substitution of 0.945. The increase in WI in cellulose and MC samples indicated the removal of lignin and other coloring agents from the samples. The FTIR spectra confirmed the modification of cellulose through the presence of -CH stretching (2956 cm-1) in MC samples. The DSC and XRD diffractogram of cellulose indicated the semi-crystalline structure of cellulose I, and after the modification, a decrease in the crystalline index and a reduction in dehydration endotherm peak intensity in MC were observed. The morphology study revealed that the cellulose from crown waste contained irregular rod-like fibril assemblies, while cellulose from peel and pomace waste contained a compact structure of fibrils. All MC samples exhibited a granular structure with a size range from 30.68 to 40.02 mu m. This study elucidates the utilization of different parts of pineapple waste for cellulose extraction and their impact on MC.