Cutoff Ostwald ripening stability of eugenol-in-water emulsion by co-stabilization method and antibacterial activity evaluation
Cutoff Ostwald ripening stability of eugenol-in-water emulsion by co-stabilization method and antibacterial activity evaluation
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DOI：
10.1016/j.foodhyd.2020.105925
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发表时间：
2020-10
影响因子：
10.7
通讯作者：
Runan Zhao;R. Song;Gege Sun;Shilin Liu;Bin Li;Yanping Cao;Yan Li
中科院分区：
文献类型：
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作者：
Runan Zhao;R. Song;Gege Sun;Shilin Liu;Bin Li;Yanping Cao;Yan Li
众所周知，含有精油的乳液在奥斯特瓦尔德成熟时不稳定。因此，为了消除这一现象，我们采用共稳定方法制备了丁香酚水包乳剂，包括由肉桂醛/壳聚糖（CA-壳聚糖）和甘油单辛酸酯（GMC）表面活性剂形成的界面层。在以GMC作为唯一稳定剂的乳液中发生了脱油。而CA-壳聚糖稳定的乳剂中由于丁香酚的密度较高，仅出现白色沉淀。在助稳定剂的存在下，乳液的粒径呈单峰分布，并在三个月内基本保持不变。长期贮存后的乳状液中虽有白色沉淀，但在光学显微镜下油滴仍保持完整。这一结果表明，助稳定剂可以帮助抑制Ostwald熟化过程。聚乙烯醇的加入有效地提高了乳液对重力分离的稳定性。当丁香酚含量达到5%和10%时，丁香酚乳剂仍保持稳定。抑菌试验和时间杀灭试验表明，包封丁香酚的抗菌活性和长期抗菌效果均优于游离丁香酚。所获得的知识提供了一种新的技术来制备丁香酚水包乳剂，其具有良好的长期稳定性和抗菌活性。
Essential oil-loaded emulsion is known to be unstable against Ostwald ripening. Hence, aiming to cut off this phenomenon, we fabricated eugenol-in-water emulsion by using co-stabilization method including interfacial layer formed by cinnamaldehyde/chitosan (CA-chitosan) and surfactant of glycerol monocaprylate (GMC). Oiling-off occurred in the emulsion with GMC as the sole stabilizer. While only white precipitates appeared in the CA-chitosan-stabilized emulsions due to the higher density of eugenol. In the presence of co-stabilizers, the particle size of emulsions showed unimodal distribution and kept almost constant within three months. Although there were some white precipitates in the emulsion after long-time storage, oil droplets still kept intact under optical microscopy. This result indicated that co-stabilizers could help to suppress the process of Ostwald ripening. The addition of polyvinyl alcohol effectively enhanced the stability of emulsions against gravitational separation. Eugenol emulsions kept stable even when eugenol content was up to 5 and 10 wt%. Antibacterial assay and time-kill experiment indicated that encapsulated eugenol had better antibacterial activity and long-term antibacterial efficiency, as compared to free eugenol. The obtained knowledge provides a novel technique to prepare eugenol-in-water emulsions, which has good long-term stability and antibacterial activity.