Oil-in-water emulsion gels stabilized with cellulosic polymers and chitosan: Themorheological and physical-chemical evaluation

Abstract

This research evaluated the use of different polymer ratios, hydroxypropyl methylcellulose (HPMC) and methylcellulose (MC) with chitosan (CHI), in the production of emulgel by emulsification. The concentration was fixed at 2 % (w/v) for all polymers. 60/40 sunflower oil-in-water emulgels were made with a cellulosic polymer:chitosan ratio of (80:20), (70:30), and (60:40), respectively. The objective was to study how different proportions of a cellulosic polymer combined with chitosan can affect the stability, microstructure, and rheology of the emulgels to be used as potential oil carrier systems. Droplet size and microscopy results show oil-in-water (O/W) emulgels, and their interface was stabilized by mixing polymeric pairs, HPMC:CHI or MC:CHI. In the thermal analysis, it was identified in the entire temperature range studied (5 to 85 °C) that both emulgels, HPMC:CHI and MC:CHI, were presented as gels (G′ > G″). Thus, the addition of CHI to the systems modified their gelling behavior. Microscopy revealed that the emulsions at the 7th and 10th week of storage showed similar characteristics to the fresh emulsion. Therefore, these results indicate that the emulgels present good thermal resistance, the predominance of elastic behavior, and can retain high concentrations of oil in their structure (96 to 99 %).