Enzymatic protein modification enhances spray-dried microencapsulation of Adiantum capillus-veneris extract: Morphology-bioactivity relationships and functional bread application

The valorization of Adiantum capillus-veneris , an underutilized medicinal fern rich in bioactive phenolics, faces challenges of stability and bioavailability during food processing and storage. This study developed spray-dried microcapsules of A. capillus-veneris hydroalcoholic extract (ACHE) using maltodextrin (MD) combined with native (whey protein concentrate [WPC] and gelatin [GEL]) versus hydrolyzed (HWPC and HGEL) protein carriers to enhance bioactive protection and enable functional food applications. Gas chromatography-mass spectrometry (GC-MS) analysis identified phytol (46.1%) as the predominant compound among 19 detected bioactives. Enzymatic hydrolysis significantly improved production yield (MD-HGEL: 89.67% vs. MD: 62.34%) and encapsulation efficiency (92.34% vs. 78.45%). Morphological characterization revealed a critical inverse relationship between particle structural integrity and extractable bioactivity: highly spherical MD-HGEL particles exhibited lowest extractable phenolics (total phenolic content [TPC]: 1.92 mg gallic acid equivalents [GAE]/g, 2,2-diphenyl-1-picrylhydrazyl [DPPH]: 44.20%, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) [ABTS]: 50.85%), indicating superior retention capacity for long-term stability applications, whereas structurally defective MD-WPC particles showed highest extractable values (TPC: 2.62 mg GAE/g, DPPH: 56.30%, ABTS: 64.80%), favoring immediate bioavailability. FT-IR confirmed physical encapsulation mechanisms, while differential scanning calorimetry-thermogravimetric analysis (DSC-TGA) demonstrated thermal protection (degradation temperature increased from 135°C to 250°C), validating baking compatibility. Antimicrobial assays revealed selective Gram-positive activity ( S. aureus : 16.8 mm vs. E. coli : 9.1 mm). Bread fortification with MD-HGEL (5% w/w) enhanced antioxidant capacity (TPC: 0.42 to 2.78 mg GAE/g; DPPH: 12.34% to 48.32%) while maintaining sensory acceptance (overall score: 7.2 vs. control: 7.5). This morphology-directed encapsulation strategy enables application-specific formulation design for bioactive delivery systems.