Linking agricultural by-product valorization to food innovation: Thermal-mechanical enhancement of Sacha inchi (Plukenetia volubilis L.) press cake

Sacha inchi (Plukenetia volubilis L.) press cake is a protein-rich by-product of oil extraction with potential as a sustainable plant-based ingredient; however, its application is limited by poor techno-functional properties. This study investigated the effects of sequential thermal–mechanical treatment (autoclaving followed by colloid milling) on the structural, nutritional, functional, and sensory properties of Sacha inchi press cake. The treatment promoted protein structural modification and matrix disruption, resulting in improved functionality. Protein content increased from 57.03 ± 0.08% to 63.96 ± 0.26% (dry basis) due to protein enrichment, while protein solubility at pH 2 increased by 65% (from 19.29 to 31.79 mg/g). Bulk density decreased by 62%, whereas water-holding capacity, oil-holding capacity, and emulsifying activity increased by 28%, 35%, and 25%, respectively. During simulated gastrointestinal digestion, treated samples exhibited higher protein solubilization in gastric (9.34 mg/g) and intestinal (11.02 mg/g) phases, suggesting improved protein accessibility during digestion. The treated press cake showed a favorable essential amino acid profile, with an essential amino acid index (EAAI) of 108 and predicted biological value (p-BV) of 106 as comparative protein quality indices. Crackers containing 10% treated press cake achieved the highest sensory acceptability among the tested formulations (8.62 ± 0.50/9). Overall, sequential autoclaving and colloid milling provide a practical approach to enhance the techno-functional and nutritional characteristics of Sacha inchi press cake for sustainable food applications.