Oxidative stability by isothermal calorimetry of solid lipid microparticles produced by particles from gas saturated solutions technique

This study aimed to investigate the application of isothermal calorimetry as technique for monitoring microparticles oxidation produced by particles from gas saturation solution (PGSS) technique. Microparticles were obtained by mixing linseed oil (9.1 g/100 g) with glycerol stearate (90.9 g/100 g). The process was carried out at 10 MPa, 55 °C for 30 min. To enhance microparticles oxidative stability, β-carotene was also added to the formulation (0.4 up to 1.6 mg/g of oil). The results showed that the fatty acid profile of the oil did not change after the encapsulation process. From the isothermal calorimetry traces, it was possible to determine the induction time (τIC) and the rates of oxidation during the inhibited (Rinh) and uninhibited (Runi) period. The microencapsulation by PGSS significantly (p < 0.05) increased τIC values of microparticles compared to the bulk oil, which resulted equal to 32 ± 1 × 104 s and 10.2 ± 2 × 104 s, respectively. On the other side, Rinh significantly decreased confirming the higher microparticles oxidative stability. β-carotene addition enhanced the oxidative stability proportionally to the concentration of the added antioxidant. At the end of the oxidation, the 3-OH-beta-apo-11-carotenal and the 3-OH-beta-apo-carotenone compounds derived from β-carotene degradation were detected.