Deep eutectic solvent served as extractant and bio-activity enhancer: applications on curcuminoids extraction and food preservation.

Deep eutectic solvents (DESs) from matrine and caprylic acid were constructed herein and used to extract curcuminoids from Curcuma longa. The DESs displayed excellent extraction efficiency that can be comparable to those with commonly used harmful organic solvents. The curcuminoids possessed high stability in the extract, which provided good anti-oxidant ability. Moreover, the extract was further used without any separation or purification process to develop biofilm that showed excellent anti-bacterial ability against E. coli and S. aureus, which was resulted from both components of DES. The prepared biofilm was thus successfully applied on strawberry preservation, where much better texture and appearance and lower weight loss of strawberry were observed as compared to those without preservation. The work provides a simple strategy to prepare bio-active film with the extract from natural herbs by bio-active ingredients based DES that acted as both extractant and bioactivity enhancer.