Acorn starch as an underutilized resource: A review of its unique properties and applications

Starch is a vital, abundant, and sustainable resource, serving as a fundamental material in the food, fermentation, pharmaceutical, and chemical industries. Acorn starch, which accounts for 50-60 % of acorn dry weight, differs from conventional starches due to its distinctive crystalline polymorphism and complex composition, including the moderate presence of tannins. These structural and compositional features markedly influence its physicochemical properties, including digestibility, pasting, and gelation. These inherent characteristics offer considerable potential for targeted modifications and versatile functional applications, particularly as bioplastics, food preservatives, stabilizers, and emulsifiers. This review systematically summarizes the isolation, multi-scale structure, functional properties, modification techniques, and application prospects of acorn starch, with the aim of supporting its broader utilization in both food and non-food sectors.