Nutritional heritage of Mie Lethek: physicochemical properties and in vitro digestibility of a traditional Javanese cassava noodle

Abstract Mie Lethek is a traditional cassava-based noodle from Yogyakarta, Indonesia, that represents Javanese culinary heritage, shaped by local agroecology and historical adaptations to rice scarcity. Produced from gaplek (sun-dried cassava) and tapioca flour using artisanal methods, it remains culturally important but scientifically undercharacterized. This study integrates cultural context with physicochemical, nutritional, and digestive analyses to characterise Mie Lethek as an ethnic food. Three commercial variants were evaluated for proximate composition, colour, texture, cooking quality, and thermal properties using differential scanning calorimetry. In vitro starch and protein digestibility, and the estimated glycaemic index (eGI), were determined using a simulated gastrointestinal model. At the same time, structural and molecular changes during digestion were examined using scanning electron microscopy and Fourier transform infrared spectroscopy. Results showed that Mie Lethek is predominantly carbohydrate-rich (~ 89%), with very low protein ( 63%), and moderate eGI values (68.6–69.3). Microstructural and spectral analyses confirmed progressive disruption of the starch matrix and molecular changes during hydrolysis. Overall, traditional raw materials and processing methods strongly influence digestive behaviour, supporting the nutritional and functional relevance of Mie Lethek for culturally rooted, sustainability-oriented dietary diversification.