Exploring novel strategies for enhanced emulsion stability: The functionalities of amphiphilic carbohydrate nanoparticles and epsilon-polylysine
The emulsifiers and interfacial technology are crucial for the stability of emulsions and govern the quality and value of a broad variety of foods. Conventional emulsifiers such as food-grade surfactants, modified starch, and gum arabic are widely used. However, there is a strong need for novel technologies for enhanced emulsion stability, especially for superior oxidative stability of polyunsaturated lipids. The hypothesis of this research was that, by strengthening the physical and electrostatic interfacial layer at the water-oil interface, the oxidative stability of emulsions can be significantly improved. To test this hypothesis, two novel strategies have been established. First, an amphiphilic carbohydrate nanoparticle, phytoglycogen octenyl succinate (PG-OSA), was created by modifying phytoglycogen, a food-based dendritic alpha-glucan (starch analogue). Due to its dendritic structure, PG-OSA has high molecular density in aqueous dispersion which may allow it to form a strong interfacial barrier against the permeation of pro-oxidative components. This is considered as the primary factor for the much reduced lipid oxidation observed in PG-OSA-based fish oil emulsions. Second, it was discovered that epsilon-polylysine, a GRAS-status antibacterial polypeptide can be used as a highly efficient anti-oxidative compound in emulsions. The interfacial electrostatic repelling of transition metal ions by the positively charged polylysine molecules could be the primary reason. When PG-OSA and polylysine were used together, the reduction of fish oil oxidation was the most significant, suggesting additive or synergistic effects between physical blocking and electrostatic repelling at the oil/water interface. In general, this work revealed novel and functionalities -for food-based nanoparticle emulsifiers. It was further observed that PG-OSA has a much reduced in vitro digestibility compared with its starch counterpart, suggesting its potential health benefit. Under a broader background, this work highlighted the potentials of using carbohydrate nanoparticles in food and non-food areas.
Yao, Purdue University.
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