Role of bran particles in the formation of dark spots on fresh wet noodle sheets: what are the dark spots?

Abstract

Background Dark spots may affect the appearance of fresh noodles during storage, even when made from flour with low ash content. The effect of flour bran content on the degree of dark spot formation in fresh wet noodle sheets (FWNS) is investigated to explain this phenomenon. Results Confocal laser scanning microscopy (CLSM) observation revealed that the wheat bran particles were responsible for the formation of dark spots on FWNS, with each bran particle core generating a single dark spot. In wheat flours with low ash content, the number of wheat bran particles causing dark spot formation on FWNS was limited, and these particles were not visible to the naked eye until their size exceeded approximately 50 μm. Tropolone, a polyphenol oxidase inhibitor (PubChem CID: 24900578) and dry heating treatment, which inactivates polyphenol oxidase, was found to inhibit or reduce the formation of dark spots. Conclusion Based on these findings, it can be concluded that bran particles, rich in polyphenol oxidase, play a key role in dark spot formation. © 2023 Society of Chemical Industry.