Extraction and modification methods of tree nut proteins and their utilization in food industry

Tree nut proteins are a well-known alternative to animal proteins owing to their high protein content, amino acid balance and functional properties. This review summarizes the extraction, modification, functional properties and food applications of proteins from major tree nuts, including walnuts, almonds, pistachios, hazelnuts and cashews. Aqueous, alkaline, and salt-assisted extraction methods, as well as emerging methods, such as ultrasound-assisted, enzyme-assisted, microwave-assisted, pulsed electric field and high-pressure processing, are critically examined. Various modification techniques, including physical, chemical, enzymatic and fermentation methods, to enhance protein solubility, emulsifying capacity, foaming properties, water-holding capacity and bioactivity are summarized. Recent developments in the utilization of tree nut proteins in bakery goods, alternative dairy products, meat analogs, protein-enriched beverages, nutraceuticals and functional foods are emphasized. The technologies emerging in this area have the potential to increase the protein yield and functionality. However, allergenicity, processing costs and commercialization issues must be addressed on a large scale. Tree nut proteins have potential for a variety of other industrial uses, along with further processing research for improved functionality and sustainability.