Microfibrillated cellulose from mangosteen (Garcinia mangostana L.) rind: Preparation, characterization, and evaluation as an emulsion stabilizer

Abstract

Aqueous microfibrillated cellulose (MFC) suspensions were prepared by extraction of ground mangosteen (Garcinia mangostana L.) rind with hot aqueous sodium hydroxide, bleaching with hydrogen peroxide, and subsequent shearing in a high pressure homogenizer. The cellulose content of the material markedly increased after the alkali and bleaching pre-treatments. The influences of number of passes through the homogenizer on characteristics of the resulting MFC were investigated. Results show that crystallinity index, degree of polymerization, viscoelaticity, and viscosity of the MFC suspensions decreased as the number of homogenization passes increased, indicating that fiber degradation occurred during homogenization. The emulsion stabilizing properties of MFC, on the other hand, were improved when the number of homogenization passes was increased. The oil-in-water emulsions stabilized by MFC (30% w/w soybean oil, 0.7% w/w MFC in aqueous phase, emulsion pH range = 6.8-7.2) obtained at the higher number of homogenization passes exhibited smaller oil droplets, stronger three-dimensional network structures, and more stable to creaming than those stabilized by MFC obtained at the lower number of homogenization passes. The creaming stability of the MFC-stabilized emulsions was reduced at low pH or high salt concentration due to electrostatic screening of the negatively charged MFC particles. Thermal treatment had little influence on the creaming stability of these emulsions. These results should improve understanding of the relationships between processing and characteristics of MFC from a novel lignocellulosic material, i.e. mangosteen rind, and lead to a potential application as an emulsion stabilizer. © 2013 Elsevier Ltd.