Enzymatic browning: The role of substrates in polyphenol oxidase mediated browning

Andrew Tilley; Mark P McHenry; Julia Anwar McHenry; Vicky Solah; Kirsty Bayliss

doi:10.1016/j.crfs.2023.100623

Enzymatic browning: The role of substrates in polyphenol oxidase mediated browning

Curr Res Food Sci. 2023 Oct 20:7:100623. doi: 10.1016/j.crfs.2023.100623. eCollection 2023.

Authors

Andrew Tilley^{1

2}, Mark P McHenry^{3

4}, Julia Anwar McHenry⁴, Vicky Solah^{1

2}, Kirsty Bayliss^{2

3}

Affiliations

¹ School of Medical, Molecular & Forensic Sciences, College of Environmental & Life Sciences, Murdoch, 6150, Western Australia, Australia.
² Food Futures Institute, Murdoch University, 90 South Street, Murdoch, 6150, Western Australia, Australia.
³ Harry Butler Institute, Murdoch University, 90 South Street, Murdoch, 6150, Western Australia, Australia.
⁴ Mt Lindesay, 56 McHenry Lane, Scotsdale, 6333, Western Australia, Australia.

Abstract

Enzymatic browning is a biological process that can have significant consequences for fresh produce, such as quality reduction in fruit and vegetables. It is primarily initiated by polyphenol oxidase (PPO) (EC 1.14.18.1 and EC 1.10.3.1) which catalyses the oxidation of phenolic compounds. It is thought that subsequent non-enzymatic reactions result in these compounds polymerising into dark pigments called melanins. Most work to date has investigated the kinetics of PPO with anti-browning techniques focussed on inhibition of the enzyme. However, there is substantially less knowledge on how the subsequent non-enzymatic reactions contribute to enzymatic browning. This review considers the current knowledge and recent advances in non-enzymatic reactions occurring after phenolic oxidation, in particular the role of non-PPO substrates. Enzymatic browning reaction models are compared, and a generalised redox cycling mechanism is proposed. The review identifies future areas for mechanistic research which may inform the development of new anti-browning processes.

Keywords: (−)-Catechin (pubchem CID: 73160); Browning; Catechol (pubchem CID: 289); Chlorogenic acid (pubchem CID: 1794427); Cysteine (pubchem CID: 5862); Ferulic acid (pubchem CID: 445858); Gallic acid (pubchem CID: 370); Oxidation; PPO; Phenolic; Polyphenol; Sinapic acid (pubchem CID: 637775); Vegetables.

Publication types

Review