Pressurized hot water crosslinking of gelatin-alginate for the enhancement of spent coffee oil emulsion stability

In this study, subcritical water was used to crosslink gelatin and alginate (G/A) at different temperatures (120 degrees C, 130 degrees C, 140 degrees C, 150 degrees C, and 160 degrees C) under constant pressure and reaction time (3 MPa, 30 min). Structural and morphological characterization was performed using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), nuclear magnetic resonance spectroscopy CH NMR), and scanning electron microscopy (SEM). The coffee oil-filled hydrogels were prepared using G/A blend by ultrasound sonication. The emulsions revealed a unimodal distribution of particles with varying diameters (654 +/- 98) nm, (509 +/- 44) nm, and (412 +/- 68) nm for G/A at 120 degrees C, 130 degrees C and 140 degrees C, respectively. However, the treatment of G/A at 150 degrees C and 160 degrees C resulted in bimodal size distribution and declined viscosity, and indicated the molecular degradation of hydrogels leading to weak repulsion force against droplet aggregation. Highly stable emulsions were observed from G/A at (120-140) degrees C, while at 150 degrees C and 160 degrees C, the emulsion exhibited poor stability during 7 weeks of storage at 5 degrees C and 25 degrees C. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

In this study, gelatin and alginate were crosslinked using subcritical water at different temperatures, leading to the formation of coffee oil-filled hydrogels with varying particle sizes. Characterization using FT-IR and other techniques revealed that hydrogels prepared within a certain temperature range showed high stability, while treatment at higher temperatures resulted in molecular degradation and unstable emulsions.