The effect of less soluble phenolic compounds of apple pomace extract on chemical and functional properties of fish gelatin-chitosan particles

The current study aims to evaluate the effect of adding 0–1 mg/100 mL less-soluble extract of apple-pomace (AP) on the functional properties of chitosan-fish gelatin (CS-FG) particles and investigate their potential as alternatives to synthetic additives. The total phenolic and flavonoid content, as well as the DPPH radical-scavenging activity of AP were 2.79 ± 0.36 mg.GAE/g, 1.94 ± 0.23 mg.QE/g and 66.3 ± 2.0%, respectively. Phloridzin (0.81 mg/g) was identified the dominant phenolic-compound in AP. Fourier-Transform-Infrared analysis confirmed the entrapment of AP within CS-FG microparticles. Scanning-electron-microscopy revealed lamellar and vesicle-like structures with smaller pores as the AP level increased. The ζ-potential of the microparticles significantly decreased with increasing AP level. The particle size ranged from 156 nm (FG) to 356 nm (CS-FG-AP 1% ). Sedimentation was observed in samples at pH 7–11 after 24 h, except for those containing 0.75 and g/100 mL extract. Encapsulation-efficiency ranged from 85.3% (CS-FG-AP 1% ) to 88.6% (CS-FG-AP 0.25%) (P < 0.05). The antioxidant-activity of unencapsulated extract decreased by 58.1% during storage, while encapsulated samples preserved around 70% of their antioxidant-activity. Solubility was 80.0% (CS-FG-AP 1% )- 91.4% (FG). Further research is needed to explore the potential application of these particles or films as environmentally friendly and sustainable materials in the food industry. • The impact of a less soluble apple pomace extract (AP) on the functional properties of chitosan-fish gelatin composite. • Observation of finer pores in the fish gelatin-chitosan structure with increased AP level. • No sedimentation in samples containing over 0.75% AP levels at pH 7–11 after 24 h. • Encapsulation efficiency exceeding 85%. • Decreasing ζ-potential of chitosan-fish gelatin composite with increasing AP leve