Nutritional quality and processing of plant proteins for healthy and sustainable foods

It is increasingly acknowledged that the transition from animal- to plant-based proteins confers substantial benefits for both human health and environmental sustainability. This review provides a critical examination of the necessity to consider not only the degree of processing applied to plant protein-based foods, particularly those derived from legume seeds, but also the nutritional quality of the resulting products. While it is well established that plant proteins exhibit a lower environmental footprint compared with their animal-derived counterparts, their digestibility is often reduced, primarily due to the matrix composition of raw ingredients. To improve protein digestibility and reduce the antinutrient content in these raw materials, a variety of processing methods are used, encompassing thermal and biological treatments (e.g. extrusion and fermentation, respectively). However, processing methods may also introduce unintended adverse effects, including protein oxidation and formation of undesirable compounds. Therefore, this review explores the paradox of sustainable processing, where process conditions may simultaneously confer environmental advantages while compromising nutritional quality. In this context, food classification systems such as NOVA are critically examined, highlighting the absence of an evidence-based system that integrates both processing conditions and product formulation in the classification of plant-based foods. Current approaches categorizing plant-based options as ultra-processed foods without accounting for the nutritional quality of their ingredients, and their ultimate digestibility, may mislead consumers and discourage the consumption of nutritionally adequate plant-based alternatives. Finally, the review emphasizes the need for the adoption of processing technologies that address the sustainability challenge and the nutritional quality of plant protein-based foods.