Vol. 9, Issue 6, Part M (2025)

The glycaemic index (GI) is a pivotal nutritional tool that classifies carbohydrate-containing foods based on their impact on postprandial blood glucose levels. Cereals and legumes, which form dietary staples globally, generally exhibit low to moderate GI values; however, cooking and processing methods can significantly modify their glycaemic response. This review comprehensively examines the effects of various thermal and non-thermal food preparation techniques, including boiling, steaming, pressure cooking, roasting, frying, fermentation, germination, soaking, and dehulling—along with industrial processing methods like extrusion, milling, parboiling, puffing, canning, and retort processing on the GI of legumes and cereals. Findings indicate that heat-intensive treatments often raise GI by promoting starch gelatinisation and enzymatic accessibility, while methods like fermentation and germination tend to reduce GI by generating organic acids, enhancing resistant starch content, and modifying the food matrix. Factors such as cooking time, cooling conditions, and food matrix integrity further modulate the GI response. Despite significant advancements, gaps remain in understanding cumulative effects, individual variability in glycaemic response, and the long-term health implications of processed diets. Future research should focus on standardising GI measurement techniques, exploring personalised dietary responses, and developing low-GI functional foods that maintain consumer acceptability and shelf-life. Understanding the interplay between processing techniques and glycaemic behaviour is vital for informed food formulation, public health nutrition strategies, and managing metabolic disorders such as diabetes and obesity.