Effects of Gelatin on Flavor Release at Low-Fat Spread Interface

In this study, we aimed to elucidate the effect of gelatin, a water-phase component, on the flavor release mechanism in water-in-oil (W/O) emulsions, used as low-fat spread model. Rapeseed oil served as the oil phase, and monoolein was employed as the emulsifier. Two W/O emulsion samples were prepared: UMG, containing only sodium chloride in the aqueous phase, and Gel-UMG, containing both gelatin and sodium chloride. Subsequently, model flavor components were incorporated into these emulsions, and the influence of gelatin in the aqueous phase on flavor release was evaluated using SPME-GC/MS. Analysis of the flavor components revealed that, in the adsorption temperature range of 30°C-50°C, fatty acid release from Gel-UMG was substantially lower than that from UMG. The interactions between gelatin and the flavor components were examined using a quartz crystal microbalance (QCM). Fatty acids, including propanoic and butanoic acids, interacted with gelatin, increasing the resonance frequency, whereas other flavor components with similar hydrophobicity (1-butanol, 2-butanol, butanal, ethyl acetate, and γ-hexalactone) showed no interaction, as indicated by the unchanged resonance frequency. Moreover, electrical conductivity, interfacial storage modulus, and water droplet size measurements collectively suggested the presence of gelatin at the oil-water interface. These findings indicate that gelatin and fatty acids in the aqueous phase of W/O emulsions may interact via the oil-water interface. This interaction likely inhibits their release into the vapor phase, decreasing the amount of fatty acids released from Gel-UMG, as detected using GC/MS analysis.