Choline is an important factor for regulating human health and is widely present in various foods. In this work, a sensor strategy based on a choline oxidase-integrated copper(II) metal−organic framework with peroxidase-like activity is constructed for one-step cascade detection of choline. The one-step cascade strategy can avoid intermediate product transferring in general multi-step reactions, and the multi-enzyme activities can be well exerted under one condition, thus exhibiting excellent catalytic activity and enhanced stability. In the integrated system, choline is catalyzed by ChO x to produce betaine and H 2 O 2 , which eventually got converted to hydroxyl radicals by the peroxidase nanozyme, oxidized the chromogenic substrate ABTS, and produced an observable absorption peak at 420 nm. A new choline detection method was thus established and showed a satisfactory linear relationship at 6−300 μM, which has been used for the choline analysis in milk.

In this study, the effect of sn-2 palmitic triacyclglycerols (sn-2 palmitic TAGs) and ratio between the two major sn-2 palmitic TAGs (OPL to OPO ratio) in human milk fat substitute...