Wine lees: from waste to O/W emulsion stabilizer

Abstract

Wine lees are the major waste from wine production, containing a noticeable amount of biomass (yeast, stalks, and peels), they could be used for the stabilization of dispersed systems such as emulsions. This work is focused on the determination of techno-functional properties of whine less produced from white grapes and industrial-grade blueberries. The interfacial characterisation was carried out by means of dilatational and interfacial shear rheology, whereas the characterisation of emulsion microstructure was assessed by droplet size distribution, rheological characterisation, and backscattering measurements. The results obtained indicated that a high amount of polyphenols were present in wine less obtained from grape fermentation with industrial-grade blueberries as an additive, moreover, their presence also caused better interfacial properties (reducing the interfacial tension up to ca. 15 mN/m). However, the comparison of dilatational and interfacial-shear rheology determined that the interfacial response was caused by a densely packed structure. Fairly low droplet sizes (⁓ 320 nm) were obtained after ultraturrax® homogenization and further passing through the Microfluidizer® device, where the emulsions were stable only in the presence of xanthan gum (0.06, 0.12, and 0.25 wt.%). However, the suitable amount of XG gum was 0.06 and 0.12 wt.% since no phase separation was observed in the emulsions generated over storage time, although flocculation phenomena took place. The results obtained exhibited emulsions with a suitable texture for the preparation of milk-shakes and brewages products, evidencing the potential of wine lees for these products.