Spray Chilling Based Microencapsulation of Sulforaphane: Process Optimization and Release Dynamics

Bioactive compounds naturally present in plants are vital in promoting health and preventing chronic diseases. Among these, sulforaphane has received considerable attention due to its well-documented anticancer, antimicrobial, and anti-inflammatory properties. In this study, sulforaphane (> 90% purity) was microencapsulated via the spray chilling technique to mask its undesirable taste and odour, enhance its bioaccessibility, and improve its stability. The spray chilling process was optimized using a Central Composite Rotatable Design (CCRD), with the optimal conditions identified as 0.68% sulforaphane–cottonseed oil concentration, 92.03% palm oil concentration, and an air inlet temperature of 17.16 °C. Under these conditions, microcapsules were produced with high encapsulation efficiency (84.56%), solubility (9.46%), and in vitro intestinal release (63.45%), while maintaining a low in vitro gastric release (17.48%). These findings underscore the potential of the spray chilling technique as an effective strategy for delivering sulforaphane in functional food and nutraceutical applications. Additionally, storage stability and release/degradation kinetics of sulforaphane extract, purified sulforaphane, and microencapsulated forms via ionic gelation and spray chilling were investigated under controlled conditions. First-order kinetic models were applied to calculate degradation rate constants (k), half-life values (t₁/₂), and coefficients of determination (R²), providing quantitative insights into the degradation behaviour of each sulforaphane form. The results showed that microencapsulation not only protected sulforaphane from environmental degradation but also enabled controlled release, particularly under high-temperature and variable pH conditions, by slowing the degradation kinetics.