Enhancement of encapsulation efficiency and improvement of oxidative values in optimized spray-dried clove ( Syzygium aromaticum L.) bud oil

Abstract

Preparation of spray-dried clove (Syzygium aromaticum L.) bud oil (CBO) was optimized. A central composite design was used with inlet air temperature (IAT) from 150 to 180 °C, pump speed (PS) from 6 to 8 mL·min−1, and needle speed (NS) from 3 to 7 s as independent variables of the process. Encapsulation efficiency (EE), free fatty acid (FFA) content, peroxide value (PV), content of oleic and linoleic acids, total phenolic content (TPC), and ferric reducing antioxidant power (FRAP) were defined as dependent variables. The morphological characteristics and functional groups of spray-dried CBO were studied using the Fourier-transform infrared spectroscopy and scanning electron microscopy. The results indicated that the highest values ​​of EE (98 ± 4%), FFA (2.9 ± 0.3 g·100 g−1 lipids), fatty acid profile (linoleic and oleic acid values), and antioxidant activity (TPC and FRAP values), and the lowest PV (1.7 ± 0.1 meq active oxygen·kg−1 lipids) in spray-dried CBO were obtained at 150 °C, 6 mL·min−1, and 3 s for IAT, PS and NS, respectively. According to ANOVA and mutual interaction impacts of processing variables, IAT and NS significantly (p < 0.05) influenced the variables related to the oxidative degree value. In conclusion, spray-dried CBO can be encapsulated to afford a high EE product showing improved oxidative values and antioxidant behaviour.