Microencapsulation of rosemary ( Rosmarinus officinalis L . ) phenolic extract and exploring its potential as a natural antioxidant barrier for frying oil

This study optimized maltodextrin concentrations and drying temperatures for the encapsulation of rosemary phenolic compounds using spray drying. Subsequently, the work examined the impact of incorporating these encapsulated phenolics (at concentrations of 75 and 150 ppm) into antioxidant-free frying oils on its quality throughout the frying process. Results showed that microcapsules with 10% maltodextrin concentration presented higher phenolic content and excellent encapsulation efficiency at 140 °C inlet temperature. During frying, polar compounds increased by 7-fold for samples with 75 ppm natural antioxidants and 4.1-fold for 150 ppm over 18 h of heating, contrasting with 35- and 28-fold for negative and positive controls, respectively. Despite an increase in total oxidation value with extended frying, oil samples containing natural antioxidants effectively controlled oxidation compared to control oil, confirmed by peroxide and thiobarbituric acid measurements up to 12 h. Thiobarbituric acid showed significant positive correlation with polar compounds, free fatty acids, dienes, and trienes, while negatively correlating with linoleic and linolenic acids, validated by principal component analysis explaining 82% of cumulative variance, with PC1 and PC2 contributing 73.38% and 9.57% variance, respectively.