Hu Zhen, Marway Heera S, Kasem Hesham, Pelton Robert, Cranston Emily D
Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L7, Canada.
ACS Macro Lett. 2016 Feb 16;5(2):185-189. doi: 10.1021/acsmacrolett.5b00919. Epub 2016 Jan 14.
The effect of tannic acid (TA) and water-soluble cellulose derivatives on the properties of Pickering emulsions stabilized by cellulose nanocrystals (CNCs) was investigated. The potential to both fully dry CNC-stabilized emulsions and to redisperse the dried emulsions in water is demonstrated. When CNCs are mixed with excess adsorbing polymer, either methyl cellulose or hydroxyethyl cellulose, followed by emulsification with corn oil, oil-in-water emulsions can be transformed without oil leakage into solid dry emulsions via freeze-drying. However, these dry emulsions exhibit droplet coalescence within the solid matrix and thus cannot be redispersed. Addition of TA (after emulsification) imparts dispersibility to the dried emulsions due to complexation between the cellulose derivatives and TA which condenses the "shell" around the oil droplets. When dried emulsions with TA are placed in water, the emulsion droplets redisperse readily without the need for high energy mixing, and minimal change in emulsion droplet size is observed by Mastersizer and confocal microscopy. Therefore, the simple addition of two sustainable components to CNC Pickering emulsions (i.e., TA and methyl cellulose or hydroxyethyl cellulose) has led to the first dried and redispersible CNC-based emulsions with oil content as high as 94 wt %. These processing abilities will likely extend the use of these surfactant-free, "green", and potentially edible emulsions to new food, cosmetic, and pharmaceutical applications.
研究了单宁酸（TA）和水溶性纤维素衍生物对由纤维素纳米晶体（CNC）稳定的Pickering乳液性能的影响。证明了将CNC稳定的乳液完全干燥并将干燥后的乳液重新分散在水中的可能性。当CNC与过量的吸附聚合物（甲基纤维素或羟乙基纤维素）混合，然后与玉米油乳化时，水包油乳液可以通过冷冻干燥转化为无油泄漏的固体干燥乳液。然而，这些干燥乳液在固体基质中表现出液滴聚结，因此不能重新分散。添加TA（乳化后）由于纤维素衍生物与TA之间的络合作用，使干燥乳液具有分散性，这种络合作用使油滴周围的“壳”凝聚。当含有TA的干燥乳液置于水中时，乳液滴很容易重新分散，无需高能混合，通过激光粒度分析仪和共聚焦显微镜观察到乳液滴尺寸变化最小。因此，向CNC Pickering乳液中简单添加两种可持续成分（即TA和甲基纤维素或羟乙基纤维素），得到了第一种含油量高达94 wt%的可干燥且可重新分散的基于CNC的乳液。这些加工能力可能会将这些无表面活性剂、“绿色”且潜在可食用的乳液的应用扩展到新的食品、化妆品和制药领域。
