Buckwheat Protein As Macromolecular Emulsifier to Stabilize Antarctic Krill Oil-Loaded Emulsion: Study on Physicochemical Properties, Microstructure, and Functional Properties

Buckwheat protein (BP) was studied in relation to oil phase volume fractions for the preparation of Antarctic krill oil (AKO) emulsions. The physicochemical properties and microstructure of BP-AKO emulsions were examined using zeta potential, droplet size, rheology, and laser confocal microscopy. The bioavailability of astaxanthin in AKO was assessed through in vitro digestion experiments. Among the emulsions tested, the BP-AKO (5-60%) emulsion, containing 5% protein and 60% oil phase, displayed the smallest particle size (1.86 μm), highest absolute zeta potential value (47.88 mV), and greatest interfacial protein adsorption rate (89.00%), indicating superior stability. Oxidative stability experiments revealed that the BP-AKO (5-60%) emulsion exhibited the lowest production of lipid hydroperoxides and malondialdehyde, reflecting excellent oxidative stability. Furthermore, the highest release of free fatty acids from the BP-AKO (5-60%) emulsion occurred during in vitro digestion, peaking at 70.17% after 120 minutes. The bioavailability of astaxanthin also reached a maximum value of 50.37%. This study provides experimental support for the use of macromolecular cereal proteins as emulsifiers to stabilize Antarctic krill oil.