Pickering water in oil emulsions prepared from biocompatible gliadin/ethyl cellulose complex particles

Abstract

Water-in-oil (W/O) emulsions have gained interest in many fields, including food, healthcare, pharmaceutical, and agriculture. However, research on Pickering W/O emulsions is limited due to the lack of available stabilizers. This study aimed to demonstrate the development of edible Pickering W/O emulsions using biocompatible and biodegradable gliadin/ethyl cellulose complex particles (GECPs) with neutral hydrophobicity as the stabilizer. The characterizations of GECPs indicated that the particle size, contact angle, and dynamic interfacial tension could be adjusted by varying the gliadin-to-ethyl cellulose (EC) ratio. The investigations of emulsions revealed that the most stable emulsions were obtained when the gliadin-to-EC ratio was 2:1. Moreover, stable emulsions could be prepared at particle concentrations higher than 1.5%. The phase inversion of emulsions from W/O to O/W occurred at 55 wt.% water. Confocal laser scanning microscopy and the theoretical calculations confirmed that GECPs formed multiple interfacial layers and acted as physical barriers against coalescence, thereby contributing to the stability of emulsions for at least 433 days; no reverse inversion occurred after 2.3 years of storage. This study provided a new approach to prepare stable Pickering W/O emulsions from GECPs. This strategy might open interesting avenues in solving the dilemma where Pickering stabilization using edible particles is required. Schematic illustration of preparation for stable Pickering W/O emulsions using biocompatible gliadin/ethyl cellulose complex particles as the particulate emulsifier. • Biocompatible gliadin/ethyl cellulose complex particles (GECPs) were fabricated using simple method. • GECPs were used to generate food-grade W/O Pickering emulsions with a stable period of at least 2.3 years. • The W/O emulsions can contain up to 50 wt.% water phase. • The type of emulsions shifted from W/O to O/W at water fraction higher than 55 wt.%. • Formation of multiple interfacial GECPs layers was confirmed.