[rprwhite]

The ascorbic acid in lemon juice is doing the work here. If you’d like read up on the science as to why it works the terms you need are polyphenol oxidase, which are the enzymes primarily responsible for browning in fruit and veg. Then also look into the Fenton chain reaction and how’s it’s interfered by ascorbic acid binding to quinones. It’ll probably be easier to find this if you focus on wine science, more so than fruit and veg in general.