Research Progress on Mechanism of Browning in Fresh-cut Lotus Root and Its Inhibition Treatments

The demand for fresh-cut fruit and vegetables is steadily rising due to enhanced living conditions and the accelerating pace of modern life. Fresh-cut lotus root, an important fresh-cut product, is favored by consumers for its convenience, nutritional value and crisp taste. Nevertheless, fresh-cut lotus root is susceptible to browning, quality degradation, diminished phenolic compounds, and a drop in antioxidant activity, leading to a decline in nutritional value. Browning is mainly caused by enzymatic reaction of phenols with oxygen catalyzed by polyphenol oxidase (PPO), leading to the formation of quinones. The quinone compounds are polymerized into dark-brown substances, such as melanin, leading to a deterioration in the color and quality of fresh cut lotus roots. Many techniques have been developed to control the browning of fresh-cut lotus roots, mostly by diminishing the activity of browning-related enzymes, limiting oxygen exposure, reducing browning byproducts, and regulating physiological metabolism. This review provides up-to-date knowledge on browning mechanism of fresh-cut lotus root based on recent domestic and foreign research. Furthermore, the factors influencing browning, including processing operations (raw material, cutting, washing, packaging) and environmental conditions (temperature, gas composition) are reviewed, and the strategies for inhibiting browning of fresh-cut lotus root are summarized based on physical, chemical, biological and combination treatment technologies. This review provides a reference for the prevention and control of browning in fresh-cut lotus root.