Yue Ding

Pea protein offers valuable nutritional and environmental advantages, yet its application in food emulsions is hindered by poor solubility and emulsifying capacity—a consequence of its inherently aggregated and rigid structure. To address this limitation, the present study developed a dual modification strategy combining controlled enzymatic hydrolysis (DH 3%) with heat assisted pH shifting. PPI was first hydrolyzed with either trypsin or pepsin, then subjected to pH 3 or pH 9 at 70°C. Trypsin hydrolysis proved markedly more effective than pepsin treatment, generating fragments with enhanced surface hydrophobicity, reduced aggregate size (~280 nm), and improved solubility, dispersibility, and emulsifying performance—benefits attributable to the stringent cleavage specificity of trypsin for lysine and arginine residues. Subsequent alkaline pH shifting (pH 9) with heating further exploited electrostatic repulsion to dissociate the aggregates to ~160 nm, yielding additional functional gains. In contrast, acidic pH shifting (pH 3) under the same heating conditions promoted extensive protein reaggregation and conferred no functional benefit. The optimally modified PPI—obtained by combining trypsin hydrolysis with alkaline pH shifting—enabled formulation of submicron sized oil in water emulsions (D_4,3=0.607±0.001 μm). These emulsions withstood 30 days of storage (D_4,3=0.837±0.003 μm) and heating at 95°C for 60 min (D_4,3=1.18±0.05 μm) with only modest droplet size increases, demonstrating notable stability. This work establishes that the synergy between enzymatic digestion and alkaline pH shifting effectively dissociates protein aggregates while avoiding the generation of excessively small peptides that would compromise emulsion stability. The dual strategy thus transforms pea protein into an efficient molecular emulsifier, offering a promising route for developing advanced plant based ingredients.

Research accumulated over the past decades has shown that mycoprotein could serve as a healthy and safe alternative protein source, offering a viable substitute for animal- and plant-derived proteins. This study evaluated the impact of substituting whey protein with fungal-derived mycoprotein at different levels (10%, 20%, and 30%) on the quality of high-protein nutrition bars (HPNBs). It focused on nutritional content, textural changes over storage, and sensory properties. Initially, all bars displayed similar hardness, but storage time significantly affected textural properties. In the early storage period (0–5 days), hardness increased at a modest rate of 0.206 N/day to 0.403 N/day. This rate dramatically escalated from 1.13 N/day to 1.36 N/day after 5 days, indicating a substantial textural deterioration over time. Bars with lower mycoprotein levels (10%) exhibited slower hardening rates compared with those with higher substitution levels (20% and 30%), pointing to a correlation between mycoprotein content and increased bar hardness during storage. Protein digestibility was assessed through in vitro gastric and intestinal phases. Bars with no or low-to-medium levels of mycoprotein substitution (PB00, PB10, and PB20) showed significantly higher digestibility (40.3~43.8%) compared with those with the highest mycoprotein content (PB30, 32.9%). However, digestibility rates for all mycoprotein-enriched bars were lower than those observed for whey-protein-only bars (PB00, 84.5%), especially by the end of the intestinal digestion phase. The introduction of mycoprotein enriched the bars’ dietary fiber content and improved their odor, attributing a fresh mushroom-like smell. These findings suggest that modest levels of mycoprotein can enhance nutritional value and maintain sensory quality, although higher substitution levels adversely affect texture and protein digestibility. This study underscores the potential of mycoprotein as a functional ingredient in HPNBs, balancing nutritional enhancement with sensory acceptability, while also highlighting the challenges of textural deterioration and reduced protein digestibility at higher substitution levels.

By considering the hydrolysates of soy protein produced by trypsin as an example, the emulsion stabilizing properties of plant-based protein fragments, and their conjugates with polysaccharides, have been investigated theoretically.