Unlocking almond milk’s potential with bio-guided processing strategies for enhanced nutrition and functionality

Almond milk, though dominant in the US plant-based milk market, faces challenges such as low protein content, gritty texture, and particle separation due to the current solid dispersion manufacturing process. To tackle this challenge, the simultaneous extraction of lipids and proteins was optimized, considering parameters like particle size, roasting level, extraction pH, and enzyme concentration, to produce almond milk with enhanced nutritional composition and consumer acceptance. Roasting increased protein extractability from almond flour due to enhanced particle size reduction. However, at finer grindings like butter and paste, light and dark roasting resulted in protein denaturation, subsequently reducing protein extractability. Regardless of the roasting level, enzymatic extraction (EAEP) increased protein extractability to 87-90%. Denaturation/aggregation during light/dark roasting reduced protein surface hydrophobicity in the aqueous extraction process (AEP). Overall, EAEP proteins exhibited lower surface hydrophobicity, except for dark roasted almonds, which led to higher protein’s surface hydrophobicity. EAEP proteins exhibited higher absolute zeta potential compared to AEP proteins. The combination of dark roasting and proteolysis increased the amount of unordered protein structures. AEP and EAEP milk formulations had higher protein (1.6 and 1.8%) and lipid contents (4.7 and 5.1%) than commercial almond milk and exhibited high protein digestibility (85-95%).  Further optimization revealed that extractions involving the use of higher solids-to-liquid ratios (SLR) increased the milk protein content. Additionally, enzymatic extraction increased oil droplet diameter while reducing milk viscosity and its immunoreactivity. Sensory tests demonstrated that higher SLR extractions resulted in milks characterized by higher mouthcoating, nuttiness, creaminess, sweetness, and bitterness (for the EAEP milk) compared to commercial samples, which were associated with astringency, grainy smell, and powdery attributes. Final AEP (pH 8.0 and 1:6 SLR) and EAEP (0.1% protease, 1:6 SLR, pH 9.0) milk formulations exhibited over 6 g of protein/serving and liking scores similar or higher than those of commercial products.