Enhanced crocin stability and controlled release in saffron-based emulsions via optimized ultrafiltration

Abstract This study presents an integrated workflow to enhance crocin stability and controlled release in saffron-based emulsions through optimized ultrafiltration and double-emulsion encapsulation. Saffron extracts were standardized according to ISO 3632 and concentrated via ultrafiltration using a PESU membrane with a 1 kDa molecular weight cut-off. Under optimized conditions (4 °C, 2 bar, 80:20 permeate-to-retentate ratio), the crocin concentration increased 6.1-fold (7568.45 mg/L) with a total recovery of 97.8 ± 2.1% and process losses below 3%. D-optimal mixture design identified the optimal W/O formulation (67% sunflower oil, 6% PGPR, 27% ultrafiltrated extract), which showed minimal droplet growth and superior color retention (R 2 = 0.96, p < 0.05). The most stable W/O/W emulsion incorporated β-cyclodextrin (1.7%) and whey protein isolate (8%), maintaining 85.3 ± 2.7% crocin retention and stable chromatic parameters over 35 days at 5–45 °C. First-order kinetic modeling revealed a degradation rate constant (k = 0.012 day -1 at 45 °C), confirming temperature-dependent stability. This integrated process bridges laboratory optimization and potential industrial application, providing a reproducible and scalable platform for formulating saffron-derived functional food systems. Graphical abstract