Traditional Indonesian cassava gethuk as a functional food for food innovation and future applications

Gethuk is a traditional Indonesian cassava-based food made from boiled or steamed cassava ( Manihot utilissima ), mashed, sweetened, and commonly served with grated coconut. Despite its cultural importance and widespread consumption in Java, particularly in Magelang, scientific discussion of gethuk remains limited and fragmented. This review critically examines the cultural, technological, physicochemical, sensory, and functional aspects of gethuk to provide a more integrated understanding of this traditional food. The article discusses the historical background and sociocultural significance of gethuk, including its association with the Grebeg Gethuk festival, which represents local identity and culinary heritage. Traditional processing methods and formulation modifications are reviewed, with an emphasis on ingredient substitution, fermentation, natural colourants, and technological innovations to improve nutritional quality, sensory acceptability, and product stability. Particular attention is given to starch transformation during processing and storage, especially the formation of resistant starch type III (RS3) through retrogradation, which may contribute to health benefits such as glycemic regulation and improved gut health. The review also addresses major challenges associated with gethuk commercialisation, including high moisture content, short shelf life, microbial susceptibility, and packaging limitations. Furthermore, future opportunities for functional food development, shelf-life enhancement, and industrial innovation are highlighted. By synthesising currently dispersed findings, this review provides a comprehensive scientific perspective on gethuk. It underscores its potential contribution to traditional food diversification, functional food innovation, and sustainable local food systems.