Identification of the key emulsifying components from the byproducts of garlic oil distillation

Steam distillation is one of the most commonly used method in the industrial extraction of garlic oil. During this process, several by-products are generated, including residual mother liquor (RML). In order to enable the comprehensive utilization of these by-products, a stable garlic oil nano-emulsion (droplet size: 162 nm) was successfully prepared using an ethanol precipitation of RML as the emulsifier in this study. To identify the critical emulsifying components in RML, it was fractionated into four sub-fractions (EP-1.0, EP-1.5, EP-2.0, and EP-2.5) via gradient ethanol precipitation and the chemical composition and emulsifying properties of each fraction were systematically investigated. Based on the excellent emulsification performance of EP-1.5, it was further studied using enzymatic deproteinization and acid hydrolysis to determine the function of its proteins and polysaccharides, respectively. The results indicated that the protein in the complex is required for emulsifying capability, while the polysaccharides enhance the emulsifying stability. These findings contribute to improving the comprehensive use of the distillation by-products of garlic oil and to the development of natural food emulsifiers from plant by-products.