DEVELOPMENT OF LEGUME-DERIVED INGREDIENTS AND FOODS ENRICHED IN BIOACTIVE COMPOUNDS USING DIFFERENT STRATEGIES

This PhD thesis is a comprehensive exploration aimed at elevating the nutritional profile of legume-derived ingredients and foods through different strategies, including exploiting the biodiversity of underutilized crops, leveraging natural modifications during germination, and repurposing food industry by-products with the integration of high-power low-frequency ultrasound technology. The research unfolds in two major segments: the first involves the investigation of lupin and the second concentrates on the recycling of a by-product from green pea canning. According to a preliminary literature review, lupin is an underutilized legume with an excellent nutritional profile; its integration in the diet could be advantageous, especially among vulnerable populations with inadequate intake of essential nutrients. Furthermore, according to numerous authors, ultrasonication has emerged as an up-and-coming technology, capable of improving many unit operations in food processing, such as extraction, homogenization, filtration, dehydration, freezing, thawing, and sanitization. In the initial phase, the study focused on Andean lupin (Lupinus mutabilis): a screening was conducted across 33 ecotypes, plus 5 controls belonging to the Mediterranean species, to assess free phenolic compounds and explore the potential of FT-NIR for evaluating antioxidant properties. Additionally, an optimized debittering method was proposed and compared with traditional ones for impact on residual alkaloids, taste profile (by e-tongue), and antioxidants. Germination was also explored as a means to enhance lipophilic antioxidants. The results unveiled the remarkable free phenolic content of L. mutabilis (294.98–1342.98 mg/kg dry matter; DM), still present after the necessary removal of alkaloids, surpassing those of the albus, angustifolius and luteus species. Notably, the models based on FT-NIR spectra showed good retrieval for free phenolics, carotenoids, tocols, and antioxidant capacity compared to conventional methods, thus paving the way for a rapid, reliable, and non-destructive characterization of lupin seeds. The proposed debittering method, employing sodium chloride or citric acid solutions, shortened the traditional treatment (from 5 days to 45 h), reduced water consumption (from 100 L/kg to 45), and better preserved the antioxidants in lupin seeds, especially free phenolics, more prone to leaching. The e-tongue effectively differentiated samples treated with the same solvent, forming distinct clusters, with bitter and umami being the main tastes. Germination led to a considerable increase in carotenoid (12-fold) and vitamin E (from not quantifiable to 74.8 mg/kg DM) contents, representing a simple and effective treatment to improve lupin nutritional value. The latter part of the thesis focused on recycling an industrially-generated canning by-product from green peas. Ultrasound-assisted protein extraction, by alkaline solubilization and isoelectric precipitation, was optimized, showcasing the effectiveness of ultrasound technology, which tripled recovery (from 21.5% to 66.6%) and reduced treatment duration fourfold (from 4 h to 1 h), when compared to the magnetic stirring method. The extract obtained had a protein content of 74.9 g/100 DM and microbial contamination below the guideline values; however, some protein degradation was also observed, likely due to pre-sampling fermentation. The by- product was then explored as a substrate for Propionibacterium freudenreichii fermentation to synthesize vitamin B12. The fermentation process yielded substantial amounts of vitamin (1374–1535 ng/g DM), and the resultant material was incorporated into bread (32.0–52.3 ng/g of vitamin), aiming to address the deficiency of B12 in strictly plant-based diets. The fortified product contained 32.0–52.3 ng/g B12, thus from 40 to 70 g of bread would provide the recommended daily intake. This section of the research highlights the potential for upcycling by-products to enhance the nutritional value of food while contributing to waste reduction. The study fills critical knowledge gaps regarding lupin bioactive compounds and also introduces sustainable approaches for by-product utilization. The optimized ultrasound-assisted protein extraction from the pea by-product demonstrates a significant breakthrough, providing the food industry with practical solutions to enhance nutritional content and create value-added products. Future research should further explore the integration of the proposed ingredients into food preparations, assessing nutrient bioaccessibility by in vitro digestion and their potential impact on health and nutritional status by cell culture. Furthermore, the consumers’ acceptability of foods and ingredients should be appraised. The outcomes of this research are poised to promote advancements in the production of healthier, sustainable, and value-added food products.