Polyphenol oxidase browning in the formation of dark spots on fresh wet noodle sheets: How dark spots formed

Yang Zhao; Ze-Hua Huang; Hui-Ming Zhou; Ke-Xue Zhu; Xiao-Na Guo; Wei Peng

doi:10.1016/j.foodchem.2020.126800

Polyphenol oxidase browning in the formation of dark spots on fresh wet noodle sheets: How dark spots formed

Food Chem. 2020 Nov 1:329:126800. doi: 10.1016/j.foodchem.2020.126800. Epub 2020 Apr 18.

Authors

Yang Zhao¹, Ze-Hua Huang², Hui-Ming Zhou³, Ke-Xue Zhu¹, Xiao-Na Guo¹, Wei Peng¹

Affiliations

¹ State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, People's Republic of China.
² State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, People's Republic of China; College of Food Science and Technology, Henan University of Technology, 100 Lianhua Street, Hi-tech Development Zone, Zhengzhou, Henan 450001, People's Republic of China.
³ State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, People's Republic of China. Electronic address: hmzhou@jiangnan.edu.cn.

PMID: 32504915
DOI: 10.1016/j.foodchem.2020.126800

Abstract

The role of polyphenol oxidase (PPO) in the browning of fresh wet noodle sheets (FWNS) was discussed. To release the chemical formation mechanism of the dark spots formed on FWNS, the reconstituted FWNS and PPO-catechol reaction systems were prepared. Different from the overall color change of FWNS, almost all the melanins in dark spots were indirect products of PPO catalysis. The PPO catalytic dehydrogenation was an essential step for the formation of dark spots, but once the phenol dehydrogenation products were formed, the dark spots could still form through a further polymerization process, even though the PPO was completely deactivated. The optimum pH for the phenolic dehydrogenation in FWNS was about 7, and the alkaline condition was advantageous to the progress of the polymerization. Comprehensively, the maximum amount of dark spots was formed at about pH 9.

Keywords: Catechol (PubChem CID: 24848193); Dark spots; Fresh wet noodle; Polyphenol oxidase browning; Tropolone (PubChem CID: 24900578); Wheat products.

MeSH terms

Catechol Oxidase / metabolism*
Color
Flour / analysis
Food Analysis
Food*
Hydrogen-Ion Concentration
Phenols / analysis
Phenols / metabolism
Triticum / chemistry

Substances

Phenols
Catechol Oxidase