Sustainable oleogel encapsulation of tilapia fish oil using protein-based cryogels: fabrication, characterization, and digestion behavior

In this study, a novel cryogel-templated oleogel system was developed by incorporating sustainable tilapia fish oil (STFO-O) into hybrid protein-based cryogels composed of whey protein isolate (WPI), fish gelatin (FG), and tannic acid (TA) as a natural polyphenolic crosslinker. Unlike previous reports on single-phase cryogels or oleogels, this dual-network system synergistically combines the advantages of protein–polyphenol interactions and porous cryogel structures for improved encapsulation, stability, and targeted release of omega-3-rich oils. The tilapia visceral oil extracted using a green deep eutectic solvent–ultrasound-assisted method, exhibited high unsaturated fatty acid content (74.07%), including 31.72% polyunsaturated fatty acids (PUFAs) and 8.47% omega-3 fatty acids, including α-linolenic acid (ALA), EPA, and DHA. The optimized WPI/FG 15 : 5-TA formulation showed excellent oil absorption (42.20 ± 0.20 g g⁻¹) and holding capacity (96.80 ± 0.69%), with a peroxide value of only 2.95 ± 0.14 meq kg⁻¹ after 8 days at 30 °C, indicating enhanced oxidative stability. FTIR analysis confirmed hydrogen bonding and successful entrapment of oil within the protein matrix. In vitro digestion demonstrated a controlled release profile, with free fatty acid (FFA) release limited to 62.17 ± 2.76% after 120 minutes compared to 83.61 ± 1.42% in the WPI-only control. These results validate the WPI–FG–TA cryogel–oleogel system as a promising and sustainable platform for delivering omega-3-enriched fish oils in functional food and nutraceutical applications.