Spruce galactoglucomannans in rapeseed oil-in-water emulsions: Efficient stabilization performance and structural partitioning

Food emulsions can be stabilized by various components, and their cost is important for the food industry that is always looking for cheaper alternatives. Consumer demand is leading food companies toward a clean label policy, and natural ingredients are the way to go. Modern forestry biorefineries offer an attractive option; novel plant-based hydrocolloids, such as spruce galactoglucomannans (GGM), are available in large quantities. Here we test their functionality and compare it with that of known food stabilizers. Rapeseed oil-in-water (O/W) emulsions stabilized by GGM and their carboxymethyl derivatives (CMGGM) were characterized in detail in terms of droplet size distribution, surface charge, and polysaccharide composition in the aqueous phase and on the droplet surface. The emulsifying and stabilizing capacities of GGM and CMGGM were compared to those of known stabilizers, namely, corn fiber gum (CFG) and gum arabic (GA), the latter of which is the gold standard in food emulsions. During high-pressure homogenization, GGM and CMGGM enabled the formation of emulsions with an average droplet size (D[3,2]) of about 400 nm and stabilized the droplets against creaming more effectively than GA (D[3,2] = 1.27 µm). The GGM and the CMGGM exhibited natural heterogeneity in their molecular composition and were distributed between the aqueous phase and the droplet interface of emulsions according to their molar mass and the CMGGM pattern of carboxymethyl substitution. This study clearly shows that wood-derived natural emulsifiers, GGM and CMGGM, meet the needs of the food industry.