Inhibition of PPO-related browning in fresh noodles: A combination of chemical and heat treatment

Enzymatic browning has been a significant factor affecting the sale of fresh noodles. This study used a combination of physical and chemical methods to achieve a long-lasting and effective anti-browning effect in fresh noodles. The results showed that the combinations of citric acid (CA), NaOH, and KOH with heat treatment blunted the polyphenol oxidase activity and improved the color of fresh noodles. Specifically, the L* value of fresh noodles stored at 6 °C treated by the combination of CA and 75 °C (CHFN-75) at 72 h (81.71) was significantly higher than that of the control at 72 h (74.42). Mixolab and confocal laser scanning microscopy showed that the combined treatment affected the protein and starch of the flour. However, the hardness and chewiness of the cooked noodles increased only slightly, and the adhesiveness decreased slightly. The innovative combination can be used as an effective way to delay the darkening of fresh noodles.