Release kinetics of the volatile compounds of oregano EO microcapsules and the relation with the antioxidant activity were studied. Different wall material (WM) to core (C) ratios (1:1 and 2:1; WM:C), addition of colloidal silicon dioxide (CSD); and different storage conditions: 23 °C (room temperature; R) and 4 °C (fridge temperature; F) were evaluated for 90 d. Volatile compounds, total phenolic content (TPC), free radical scavenging activity (FRSA), and Trolox equivalent antioxidant capacity (TEAC) were measured. The formulas 2:1 (WM:C) (R and F) without CSD behaved differently from the rest, exhibited a higher antioxidant activity, and released less amount of volatile compounds after 90 d. These treatments grouped together in the cluster analysis, showing the highest TPC (81.54 mg gallic ac/g), FRSA (8.66%), and TEAC (12.35 μg Trolox/g). The addition of CSD facilitated the released of volatile compounds through storage time and promoted losses in the antioxidant activity. The temperature had a significant effect in most of the evaluated variables. However, this effect was more noticeable in F2 (1:1, CSD). PRACTICAL APPLICATION Oregano essential oil has antioxidant, antimicrobial, and sensory preserving properties. However, it is susceptible to volatilization and is degraded by external factors. Its addition into food matrices is restricted due to low solubility and hydrophobicity. The antioxidant activity of oregano EO is preserved after the process of microencapsulation by spray-drying that extends its stability during storage. Oregano EO microcapsules are an alternative of delivery which protects and extends the shelf life of this essential oil, overcomes stability related limitations and preserves its desirable characteristics allowing these kind of microcapsules to be later incorporated into food products. These microcapsules could be used as a natural additive/flavouring with antioxidant properties.

中文翻译：

---

喷雾干燥法制备牛至精油微胶囊的抗氧化稳定性研究

研究了牛至EO微胶囊挥发性化合物的释放动力学及其与抗氧化活性的关系。不同的壁材 (WM) 与芯材 (C) 的比例（1:1 和 2:1；WM:C），添加胶体二氧化硅 (CSD)；和不同的储存条件：23°C（室温；R）和 4°C（冰箱温度；F）评估 90 d。测定了挥发性化合物、总酚含量 (TPC)、自由基清除活性 (FRSA) 和 Trolox 等效抗氧化能力 (TEAC)。不含 CSD 的配方 2:1 (WM:C) (R 和 F) 与其他配方不同，表现出更高的抗氧化活性，并且在 90 d 后释放的挥发性化合物量更少。这些处理在聚类分析中组合在一起，显示出最高的 TPC（81.54 mg 没食子 ac/g）、FRSA（8.66%）和 TEAC（12.35 μg Trolox/g）。CSD 的添加促进了挥发性化合物在储存期间的释放，并促进了抗氧化活性的损失。温度对大多数评估变量都有显着影响。然而，这种效果在 F2（1:1，CSD）中更为明显。实际应用牛至精油具有抗氧化、抗菌和感官保护的特性。但易挥发，受外界因素影响而降解。由于低溶解度和疏水性，其添加到食品基质中受到限制。牛至 EO 的抗氧化活性在通过喷雾干燥进行微胶囊化后得以保留，从而延长了其在储存期间的稳定性。牛至 EO 微胶囊是一种替代递送方式，可保护并延长这种精油的保质期，克服了与稳定性相关的限制并保留了其理想的特性，从而使此类微胶囊以后可以掺入食品中。这些微胶囊可用作具有抗氧化特性的天然添加剂/调味剂。