Inhibition of L-Cysteine on the Browning of Fresh Wet Noodles.

Xin-Ting Wu,Ke-Xue Zhu,Xiao-Na Guo

doi:10.3390/foods10061156

Abstract

This research explored the effect of L-cysteine on the browning of fresh wet noodles (FWN). With the increasing addition of L-cysteine (0.02–0.1%), the ΔL* decreased and Δa*, Δb* increased. The L-cysteine could reduce the pH value and polyphenol oxidase (PPO) activity and increase the retention rate of polyphenol of FWN. It suggested that L-cysteine could inhibit the browning of FWN by decreasing pH value, PPO activity, and the oxidation of polyphenols. In the in vitro PPO solution, the inhibitory effect of L-cysteine on PPO activity was related to the decrease in pH and the ability of chelating Cu2+. According to UPLC-TOF-MS analysis, L-cysteine could reduce the generation of browning products, which suggested that L-cysteine could react with the browning intermediate product (quinone) and generate a light-colored substance (-C9H10NO4S). L-cysteine effectively inhibited the browning of FWN and had the potential to be used in noodle industry.

Highlights

Noodles are one of the staple foods in Asian counties, composed of wheat flour, water and additives
∆L* of fresh wet noodles (FWN) gradually decreased with the increase in the addition amount of L-cysteine
In the model system of polyphenol oxidase (PPO)-chlorogenic acid, the results indicated that the model system of PPO-chlorogenic acid, the results indicated that the mechanism of Lmechanism of L-cysteine on browning inhibition was related to the formation of a thiolcysteine on browning inhibition was related to the formation of a thiol-conjugated reaction conjugated reaction product [38]

Summary

Introduction

Noodles are one of the staple foods in Asian counties, composed of wheat flour, water and additives (salt and sodium carbonate). Noodles are mainly classified into dried noodles, semi-dry noodles and fresh wet noodles (FWN) according to the difference in water content [1]. Due to the high moisture content, the overall color of FWN changes from bright milky white or light yellow to gray or brown during storage, affecting its quality and sale [3]. Previous studies have confirmed that polyphenol oxidase (PPO) played an important role in the browning of alkaline wet noodles [5]. During the processing and storage of flour or FWN, wheat PPO maintains high activity, and it is difficult to inactivate PPO by heat treatment without destroying gluten of flour [6,7]. There are many external factors that affect browning of FWN, including the amount of water added, pH, vacuum, storage temperature, and browning inhibitors. The vacuum mixing could reduce the browning of FWN and increase the brightness of the initial noodles [12]

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Conclusion