The effect of extrusion on the bioactive compounds and antioxidant capacity of novel gluten-free expanded products based on carob fruit, pea and rice blends

The bioactive compounds (inositol phosphates, alpha-galactosides, protease inhibitors, lectins, and phenolic compounds) and antioxidant activity (ORAC) of different rice-legume (carob fruit and pea) blends were evaluated in non-extruded (as control) and extruded formulations. Extrusion reduced (p < 0.05) the inositol phosphates (5.7-30.9%) and lectin (50-97%) contents, whereas the protease inhibitors were eliminated. The alpha-galactosides content increased (p < 0.05) after extrusion, while the different phenolic compounds studied were not affected to the same extent. A strong positive correlation was found between the ORAC values and total phenolic content in all the samples. The effect of extrusion process was well described by principal component analysis and was mainly characterised by the first principal component. The amounts of these bioactive compounds present in the novel gluten-free ready-to-eat foods (especially both formulations with 10% carob fruit) could allow them to be considered functional foods that are suitable for a healthy lifestyle, helping to increase pulse consumption. Industrial relevance: This research responds to the growing interest of consumers to find new healthy products, and, therefore, it may allow the food industry to meet their demand of functional foods. Extrusion cooking is a processing technique widely used in the food industry. The results obtained in this study demonstrated that blends based on legumes (carob fruit and pea) and rice can be a novel source of bioactive compounds to be used in the production of expanded gluten-free snack or breakfast cereals-like products with health promoting functions.