Production strategies and functional applications of soybean oilseed cake protein hydrolysates in low-cost foods: A review

Soybean oilseed cake (SOC) is a low-value by-product of oil extraction that contains 40–50% protein. Its native form suffers from poor solubility, bitterness, and suboptimal functionality, while premium sources like soy isolate remain prohibitively expensive for low-cost formulations. To address these challenges, this review aims to thoroughly evaluate production strategies for SOC protein hydrolysates (SOCH) and their integration into affordable food products. Amazing results show that while chemical methods (HCl/NaOH) achieve cost-effective 60–80% yields despite milder bioactivity, enzymatic hydrolysis with Alcalase, Flavourzyme, or pepsin yields 80–95% degree of hydrolysis, producing SOCH with superior solubility (>90% at neutral pH), potent antioxidant activity (DPPH scavenging 70–85%), ACE-inhibitory potency (IC50 μg/mL), and millet-SOCH blends show improved gelation, foaming, and sensory appeal (scores >7/9). By strengthening staples like millet porridges, extrudates, biscuits, and drinks at 15–30% inclusion, increasing protein content to 15–25%, preventing lipid oxidation (TBARS reduction 40–60%), prolonging shelf life, and reducing bitterness for widespread consumer acceptance, these hydrolysates offer workable solutions at optimized costs of $2–4/kg via scalable agro-industrial processes. In addition to addressing important issues like peptide allergenicity and regulatory scaling in smallholder contexts, this study adds innovative features like hybrid hydrolysis for optimal functionality-cost balance and nanoencapsulation for bitterness management. In the end, it guides food innovation by promoting SOC valorization for circular economies and the UN SDGs on hunger and sustainability. In addition to addressing important issues like peptide allergenicity and regulatory scaling in smallholder contexts, this study adds innovative features like hybrid hydrolysis for optimal functionality-cost balance and nanoencapsulation for bitterness management. In the end, it guides food innovation by promoting SOC valorization for circular economies and the UN SDGs on hunger and sustainability. Graphical abstract A flow diagram features the process of converting soybean oilseed cakes into high-protein snacks and nutritional beverages. Review methodology A systematic literature search was conducted to compile relevant studies on protein hydrolysates, with special emphasis on oilseed protein hydrolysates as cost-effective and sustainable protein sources. Databases including Google Scholar, ScienceDirect, and CAB Abstracts were searched using keywords such as “protein hydrolysates,” “oilseed proteins,” “functional properties,” “enzymatic hydrolysis,” “antioxidant activity,” and “food applications.” Additional relevant articles were identified through backward citation tracking of selected papers. Recent review articles and book chapters were also screened to capture advancements in production techniques, functional and nutritional attributes, and emerging applications. The retrieved literature was further refined and validated through expert academic consultation to ensure comprehensiveness and relevance to the topic. HIGHLIGHTS • Low cost, high-protein by-product that can be used to create functional foods. • High-quality peptides with better functionality and bioactivity. • Hydrolysates have outstanding solubility, emulsification, and gelation qualities. • Hydrolysates as potent antioxidant, antihypertensive, and antidiabetic properties. • Sustainable nutrition, circular economy and reasonably priced, high-protein food.