Pinhão Starch-Based Cryogels with Oregano Essential Oil for Antifungal Active Food Packaging

Abstract The practical applications of essential oils are limited by their hydrophobicity, volatility, and instability; however, cryogels have emerged as promising carriers that can overcome these challenges by enabling the controlled release of bioactive compounds. This study aimed to synthesize and characterize cryogels based on pinhão starch and loaded with oregano essential oil (OEO). Cryogels were produced with pinhão starch (9%, w/v) and incorporated with OEO at concentrations of 15 and 25% (v/w, in relation to starch). The process involved gelatinization, freeze/thaw cycles, and freeze-drying. The OEO was evaluated for its chemical composition, thermogravimetric analysis, functional groups, and in vitro antifungal activity. The cryogels’ morphological, structural, thermal, and chemical properties were evaluated, along with their antifungal activity. The major constituents of OEO were carvacrol (69.22%), o-cymene (14.31%), caryophyllene (5.09%), and γ-terpinene (5.06%). All cryogels exhibited the typical morphology of these materials, with a well-defined internal macroporous structure. The incorporation of OEO increased cryogel density from 0.086 g/cm 3 (control) to > 0.092 g/cm 3 , while slightly reducing porosity from 88.3% to < 87.4%. The control cryogels exhibited a water absorption capacity of approximately 1300%, while OEO-loaded cryogels showed reduced values (~ 1190-1206%), with no significant difference between the two OEO concentrations. The thermal stability of OEO was enhanced by its incorporation into the cryogel structure. While free OEO began to degrade at a lower temperature of 186.1 °C, the OEO within the cryogels showed greater thermal resistance, with degradation observed only at temperatures up to ~ 320 °C. Cryogels containing 15% and 25% OEO exhibited high antifungal activity against Penicillium crustosum and Aspergillus flavus . Pinhão starch-based cryogels demonstrated strong potential as sustainable carriers for OEO for future application in active food packaging, due to their favorable physicochemical properties, enhanced thermal stability, and antifungal activity.