The bioactivity of essential oils applied in foods to act as natural preservatives can be reduced due to interactions with other components of the food matrix. Microencapsulation can help to increase the functionality of these compounds. In addition, the electrostatic interaction between proteins and polysaccharides can result in double-layered encapsulating structures, ensuring greater protection to essential oils than using only protein as surface active agent. In this work, pink pepper essential oil was microencapsulated by spray drying of single-layer emulsions, stabilized by soy protein isolate (SPI), and of double-layer emulsions, stabilized by soy protein isolate/high methoxyl pectin (SPI/HMP). Pink pepper essential oil showed predominance of α-pinene, β-pinene, β-mircene, δ-3-carene, d-limonene, and germacrene D. Compared to SPI microcapsules, SPI/HMP microcapsules better preserved the total volatile content identified in pure oil, showed less water adsorption during storage at relative humidity ≥75% and improved antimicrobial properties. When stored for 20 days (25 °C/RH = 52.8%), both microcapsules allowed more gradual release of volatiles compared with non-encapsulated oil. Microencapsulation by spray drying did not have negative effects on the antioxidant activity of the encapsulated oil, as the microcapsules showed similar results to the non-encapsulated oil, around 11 μg Trolox/mg of oil. After storage, however, the non-encapsulated oil showed greater losses of its antioxidant activity due to higher rates of volatile release. In the in vitro antimicrobial activity assay, both microcapsules inhibited growth of Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes and Listeria innocua, although no inhibition was observed against Gram-negative bacteria. When added in milk, both microcapsules reduced bacterial growth, whereas non-encapsulated oil showed no satisfactory inhibition. Faster reduction of microbial growth in milk was observed for SPI/HMP microcapsules. Inhibition results were better for skim milk than for whole milk, suggesting that the interaction of essential oil with other lipids present in milk decreased its bioactivity. Microencapsulation positively affected the functionality of pink pepper essential oil, highlighting its potential for application as a natural preservative in food products.

由于与食品基质中其他成分的相互作用，可以降低食品中用作天然防腐剂的精油的生物活性。微囊化可以帮助增加这些化合物的功能。此外，蛋白质和多糖之间的静电相互作用可导致双层包封结构，与仅使用蛋白质作为表面活性剂相比，可确保对精油的更大保护。在这项工作中，将胡椒粉精油通过喷雾干燥由大豆蛋白分离物（SPI）稳定的单层乳剂和由大豆分离蛋白/高甲氧基果胶（SPI / HMP）稳定的双层乳剂进行微囊化。粉红胡椒精油主要表现在α-pine烯，β-pine烯，β-二茂烯，δ-3-胡萝卜素，d与柠檬微囊相比，SPI / HMP微囊更好地保留了纯油中确定的总挥发物含量，在相对湿度≥75％的储存条件下显示出更少的水吸附，并改善了抗菌性能。当储存20天（25°C / RH = 52.8％）时，与未包封的油相比，两个微囊均允许更多的逐步释放挥发物。喷雾干燥进行的微囊化对囊化油的抗氧化活性没有负面影响，因为微囊显示出与未囊化油相似的结果，大约为11μgTrolox / mg油。然而，在储存后，由于较高的挥发性释放速率，未包封的油显示出其抗氧化活性的更大损失。在体外抗菌活性测定，两种微胶囊均抑制金黄色葡萄球菌，枯草芽孢杆菌，单核细胞增生李斯特菌和无毒李斯特菌的生长，尽管未观察到针对革兰氏阴性菌的抑制作用。当添加到牛奶中时，两个微胶囊都会减少细菌的生长，而未包囊的油则没有令人满意的抑制作用。对于SPI / HMP微胶囊，观察到牛奶中微生物生长的更快降低。脱脂牛奶的抑制效果要优于全脂牛奶，这表明精油与牛奶中存在的其他脂质的相互作用降低了其生物活性。微囊化积极地影响了粉红胡椒精油的功能，突出了其在食品中用作天然防腐剂的潜力。