<p>The impact of hydrogen peroxide (H₂O₂) on the prevention of browning in fresh-cut yacon (<i>Smallanthus sonchifolius</i> (Poepp.) H. Rob) was explored. Results revealed that H₂O₂ treatment obviously inhibited the increase of browning index and browning degree. This influence had nothing to do with the activity of polyphenol oxidase, but was closely related to the biosynthesis of lignin via activating the enzymes within phenylalanine ammonia-lyase, cinnamyl alcohol dehydrogenase cinnamate 4-hydroxylase, and 4-coumarate CoA ligase. Moreover, apart from activating phenylpropane pathway, H₂O₂ treatment also promoted the ascorbic acid (AsA)- glutathione (GSH) cycle, elevating total phenolic content, AsA and GSH. These non-enzymatic antioxidants enhanced the antioxidant capacity and alleviated the membrane lipid damage of fresh-cut yacon, as testified by higher levels of unsaturated fatty acid and phospholipids and lower level of MDA. These findings highlight that H₂O₂ treatment can effectively alleviate the browning in fresh-cut yacon by modulating lignin accumulation and protecting against lipid membrane degradation.</p>