College of Food Science and Technology, Huazhong Agricultural Univ., 430070, Wuhan, Hubei, People's Republic of China.
J Food Sci. 2019 Jun;84(6):1427-1438. doi: 10.1111/1750-3841.14610. Epub 2019 May 9.
Thyme essential oil-loaded microcapsules (TMS) were fabricated using natural polysaccharide chitosan (CS) and sodium alginate (SA) as the shell material via the method of layer-by-layer (LBL) assembly. The accumulated release rates of thyme oil and microcapsules at 4 °C were 42.50% and 10.16%, respectively. After heating at 100 °C for 5 hr, the release rate of the 0, 2, 4, 6 layers assembled microcapsules were 100%, 48.84%, 28.38%, 19.3%, severally. Microcapsules also had good pH sensitivity in the range of 4 to 10. Antimicrobial function studies showed that the microcapsules are more effective than thyme oil for three tested microorganisms. When the temperature rose from 37 °C to 121 °C, the antibacterial zone of thyme oil gradually decreased from 18.5 ± 0.6 mm to 12.3 ± 0.6 mm, although inhibition rate of microcapsules increased from 87.97% to 99.75%. The antibacterial effect of thyme oil declined with the increase of pH, in terms of microcapsules, the efficiency was better under acidic or alkaline conditions. The thyme oil microcapsules can suppress the growth of Staphylococcus aureus in milk and prolong its shelf life. It was determined that this microcapsule could be a potential alternative as a natural antimicrobial agent in food and pharmaceutical industries. PRACTICAL APPLICATION: This work provided release performance and mechanism of layer-by-layer (LBL) thyme oil microcapsule under different conditions, and further studies showed its antibacterial ability to explore how herb essential oils can be potentially applied in food packaging and antibacterial areas.
负载百里香精油的微胶囊（TMS）是通过层层（LBL）组装的方法，使用天然多糖壳聚糖（CS）和海藻酸钠（SA）作为壳材料制备的。在 4°C 下，百里香油和微胶囊的累积释放率分别为 42.50%和 10.16%。在 100°C 加热 5 小时后，组装的 0、2、4、6 层微胶囊的释放率分别为 100%、48.84%、28.38%、19.3%。微胶囊在 4 到 10 的 pH 值范围内也具有良好的 pH 敏感性。抗菌功能研究表明，微胶囊对三种测试微生物比百里香油更有效。当温度从 37°C 升高到 121°C 时，百里香油的抑菌圈逐渐从 18.5±0.6mm 减小到 12.3±0.6mm，尽管微胶囊的抑制率从 87.97%增加到 99.75%。百里香油的抗菌效果随 pH 值的增加而降低，就微胶囊而言，在酸性或碱性条件下效率更好。百里香精油微胶囊可以抑制牛奶中金黄色葡萄球菌的生长，延长其保质期。确定这种微胶囊可以作为食品和制药行业中天然抗菌剂的潜在替代品。实际应用：本工作提供了不同条件下层状（LBL）百里香精油微胶囊的释放性能和机制，进一步研究表明了其抗菌能力，以探索草药精油如何在食品包装和抗菌领域得到潜在应用。
