Potatoes are the fourth largest food crop in the world after rice, wheat and maize, and their production in China accounts for 90.07% of Asian output and 67.30% of world's total (Al-Mughrabi, Coleman, Vikram, Poirier, & Jayasuriya, 2013). Potatoes not only provide energy through the high starch content, but also contain a lot of vitamins B3, B6 and C, as well as mineral elements such as potassium, magnesium and iron (Andre et al., 2007). Meanwhile, potatoes contain phenolics, flavonoids and carotenoids, which have antioxidant, anti-cancer and antihypertensive activities (Ezekiel, Singh, Sharma, & Kaur, 2013). All these ingredients are nutritious and have a positive impact on human health, especially the obese people (Turner, Austin, McDonough, & Rooney, 2012). Potatoes have been utilized in many forms, but many consumers are unaware of their health benefits (Camire, 2016). Potatoes have a higher protein content than most other tubers and roots (Beals, 2019).

In recent years, potato protein, as a byproduct of potato starch processing, has attracted increasing attention because of its special structure and functional properties (Vikelouda & Kiosseoglou, 2004). During the production of potato starch, a large amount of wastewater with a crude protein content of about 1.5 g/100 g is produced, but it is usually discarded (Mu, Tan, & Xue, 2009). Additionally, it has also been reported that the processing of one metric ton of potato into starch can produce 5 to 12 m3 of potato juice, which contains 300 to 410 g/kg proteins, equivalent to 20% to 60% of proteins present in the tuber (Renard & Christine, 2000; Wojnowska, Poznanski, & Bednarski, 1982). These data indicate that the recycling and utilization of potato protein is of great significance to the environment and economic development.

Potato protein contains 18 amino acids and thus has a high nutritional value, superior to most plant-based proteins and close to the protein in eggs in this respect (Bártová et al., 2009). Additionally, potato protein contains a lot of lysine, which can be used as a good substitute for wheat products to prevent wheat allergy (Vreugdenhil, Bradshaw, Gebhardt, Govers, & MacKerron, 2008). Moreover, potato protein can prevent some diseases, such as cardio cerebrovascular disease, high blood sugar and high blood pressure (Kim et al., 2006; Park et al., 2005). Furthermore, potato tuber proteins mainly consist of glycoprotein (40 kDa), complex protein (22 kDa) and protease inhibitor, which have the potential function of foam formation and emulsion stabilization (Hannapel, Peterson, Estiekema, & Suh, 1990; Schmidt, Damgaard, Greve-Poulsen, Larsen, & Hammershoj, 2018). All these reports suggest the potential application values of potato protein in the food field. However, potato protein is prone to denaturation during the production process due to heat treatment, thus restricting its application in the food industry. Previous studies have shown that potato proteins as a crude extract dried by spray drying exhibited poor solubility and emulsifying properties (Renard & Christine, 2000), suggesting the necessity to modify potato protein to maximize its utilization.

In addition, in recent years, many studies have been performed on the modification of potato protein, but these studies have not been comprehensively evaluated. Therefore, this paper reviews various aspects of potato protein processing related to its application in the technical industry. Firstly, the amino acid composition, structure and basic functional properties of potato protein are reviewed. Additionally, the potato protein separation and extraction methods are reviewed and discussed in detail, with a focus on their processing conditions and effects on yield and purity. Moreover, we investigate the modification technologies (traditional and emerging technologies, including physical, chemical and enzymatic methods) for improving the functional properties of potato protein. Finally, the recent possible applications of potato protein in the food field are presented. This review will provide useful information for further development and application of potato protein.