Influence of proanthocyanidins (condensed tannins) on pulse protein polymer size and associated properties

Potential for pulse proteins in plant-based meat alternatives is limited by weak protein polymer interactions. This work examined the effects of proanthocyanidins on pulse protein crosslinking. Proanthocyanidins with degree of polymerization, mDP, 1-19.5 were reacted with soybean (control) and pulse (pea, faba, and lentil) proteins. Changes in properties, M_W, and post-extrusion texture were evaluated. Pea and faba proteins exhibited stronger proanthocyanidin binding (K_d, 3.13-8.74), but lower binding capacity (B_max, 0.29), and change in surface hydrophobicity, (ΔH_o, -56 %) vs soy and lentil (K_d, 249-935, B_max, 0.59-0.76, ΔH_o, -67 %). Polymeric proanthocyanidins preferentially cross-linked high M_W protein subunits, forming complexes of >600 kDa and increasing protein denaturation temperature by 2.9-12.1 °C. The proanthocyanidins increased hardness (1.8-15×) and chewiness (1.6-13×) of texturized pulse proteins, suggesting increased protein network density during extrusion. The findings highlight the potential of proanthocyanidins to enhance pulse protein polymer interactions and improve their textural properties.