Inhibition of aspartic acid on the darkening of fresh wet noodles

Abstract

This research explored the effect and mechanism of aspartic acid (Asp) on the darkening of fresh wet noodles (FWNs). With increase in the addition of Asp (0.1%-0.9%), DL* and pH of FWN reduced significantly (P < 0.05). Asp could reduce polyphenol oxidase (PPO) activity and increase its retention rate of polyphenol of FWN. When FWNs were adjusted to the same pH by Asp, malic acid (Mal) and hydrochloric acid (HCl), DL* and PPO activity of FWN with Asp were lower than that of other two acids. In the vitro PPO solution, the inhibitory effect of Asp on PPO activity was related to the decrease in pH and the ability of chelating Cu 2+ . According to UPLC-TOF-MS analysis, Asp could also react with PPO browning products (-C 12 H 9 O 4 , -C 24 H 19 O 2 and -C 12 H 7 O 5 ), transforming browning products into some light-coloured products. Asp effectively inhibited the darkening of FWN and had the potential use in noodle industry.