Thermal processing under mild acidic conditions modulates metabolite profile and emulsifying functionality of Moringa...

This study investigated the effects of thermal treatment (30, 55, and 85 °C) under mild acidic conditions (pH 4.5) during protein precipitation on structural characteristics, emulsifying properties, metabolite profile and protein composition of Moringa leaf protein (MoLP) from two cultivars (local Thai and PKM-1). Moderate heating at 55 °C resulted in the highest protein recovery, reaching 4.59% and 2.47% for Thai and PKM-1 cultivars, respectively. In contrast, treatment at 85 °C reduced protein content to 54.8% and 50.1%. Structural analyses indicated heat-induced unfolding, thiol-disulfide rearrangement, decreased thermal stability, and increased β-sheet formation, indicating protein aggregation. SDS-PAGE further confirmed protein alterations, particularly affecting RuBisCO-associated proteins. LC-MS/MS analysis demonstrated selective proteomic remodeling, with retention of metabolic enzymes and enrichment of stress-related proteins, whereas thermolabile photosynthetic proteins declined after heating. Metabolomic analysis showed cultivar-dependent responses, with PKM-1 exhibiting greater thermal resilience. Heat treatment at 55 °C substantially improved emulsion stability, increasing from 20 to 86 min in local Thai cultivar and from 119 to 208 min in PKM-1 cultivar. Overall, moderate thermal treatment at 55 °C provided the balance between protein recovery, structural integrity, and emulsifying functionality of MoLP, demonstrating the potential of MoLP as plant-based emulsifier.