Broccoli by-products, traditionally considered inedible, possess a comprehensive nutritional and functional profile. These by-products are abundant in glucosinolates, particularly glucoraphanin, and sulforaphane, an isothiocyanate renowned for its potent antioxidant and anticarcinogenic properties. Broccoli leaves are a significant source of phenolic compounds, including kaempferol and quercetin, as well as pigments, vitamins, and essential minerals. Additionally, they contain proteins, essential amino acids, lipids, and carbohydrates, with the leaves exhibiting the highest protein content among the by-products. Processing techniques such as ultrasound-assisted extraction and freeze-drying are crucial for maximizing the concentration and efficacy of these bioactive compounds. Advanced analytical methods, such as high-performance liquid chromatography–mass spectrometry (HPLC-MS), have enabled precise characterization of these bioactives. Broccoli by-products have diverse applications in the food industry, enhancing the nutritional quality of food products and serving as natural substitutes for synthetic additives. Their antioxidant, antimicrobial, and anti-inflammatory properties not only contribute to health promotion but also support sustainability by reducing agricultural waste and promoting a circular economy, thereby underscoring the value of these often underutilized components.

This study identified the compounds obtained from four native Dehesa plants, which were holm oak, elm, blackberry and white rockrose, and evaluated their ability to inhibit the growth and production of aflatoxins B₁ and B₂ of two strains of mycotoxigenic Aspergillus flavus. For this purpose, phenolic compounds present in the leaves and flowers of the plants were extracted and identified, and subsequently, the effect on the growth of A. flavus, aflatoxin production and the expression of a gene related to its synthesis were studied. Cistus albidus was the plant with the highest concentration of phenolic compounds, followed by Quercus ilex. Phenolic acids and flavonoids were mainly identified, and there was great variability among plant extracts in terms of the type and quantity of compounds. Concentrated and diluted extracts were used for each individual plant. The influence on mold growth was not very significant for any of the extracts. However, those obtained from plants of the genus Quercus ilex, followed by Ulmus sp., were very useful for inhibiting the production of aflatoxin B₁ and B₂ produced by the two strains of A. flavus. Expression studies of the gene involved in the aflatoxin synthesis pathway did not prove to be effective. The results indicated that using these new natural antifungal compounds from the Dehesa for aflatoxin production inhibition would be desirable, promoting respect for the environment by avoiding the use of chemical fungicides. However, further studies are needed to determine whether the specific phenolic compounds responsible for the antifungal activity of Quercus ilex and Ulmus sp. produce the antifungal activity in pure form, as well as to verify the action mechanism of these compounds.

Papaya (Carica papaya L.) processing generates by-products that can serve as sustainable sources of bioactive compounds. This study aimed to extract and characterize the bioactive compounds from the peel and seeds of different papaya varieties and evaluate their antioxidant and antimicrobial potential, as well as their behavior under simulated digestion. The results indicated that Maradol seeds possessed the highest total phenolic content and antioxidant values, demonstrating superior compositional and functional profiles, and that seed extracts overall had greater antibacterial efficacy than peel extracts, with Hawaiian seed extracts exhibiting the greatest overall inhibition. Furthermore, under simulated gastrointestinal conditions, the combined extracts from peel and seeds effectively preserved phenolics through the gastric and intestinal phases and notably enhanced the generation of acetate and propionate during colonic fermentation. These findings robustly substantiate the functional valorization of papaya by-products and suggest that selecting extracts based on their specific bioactive profiles can significantly enhance their applications as natural, functional ingredients in the food industry.

The almond shell is a byproduct that contains bioactive compounds such as phenolic compounds and flavonoids, which possess antioxidant and anticancer properties. In this study, these compounds were extracted from the shells of different almond varieties (Lauranne, Marta, Constanti, D01-188, S4017, Vairo) to evaluate their antioxidant, antibacterial, and antifungal activities in vitro. The optimal almond varieties for specific bioactivities were identified. Lauranne, due to its elevated phenolic content, exhibited the highest antioxidant capacity. In contrast, S4017, despite its comparatively lower phenolic concentration, demonstrated the most potent antibacterial activity. Constanti, characterized by its high content of both phenolic and flavonoid compounds, is well-suited for promoting overall health and enhancing food preservation, while Vairo exhibits notable antifungal activity against specific fungal species. These findings suggest that selecting almond varieties based on their bioactive compound profiles can enhance their health benefits and applications in the food and pharmaceutical industries.

Mango (Mangifera indica L.) processing generates peel and seed by-products with high potential for valorization as sources of phenolic-rich ingredients. In this study, peel and seed from four Ecuadorian cultivars were extracted by ultrasound-assisted hydroalcoholic extraction and characterized for total phenolics, phenolic profile by HPLC-ESI-QTOF, antioxidant capacity (DPPH and ABTS), and antimicrobial activity against food-relevant bacteria. A dynamic in vitro gastrointestinal digestion model was also applied to evaluate digestion-driven changes in phenolic-related measurements and antioxidant response, and to assess colonic fermentation outputs, including short-chain fatty acids and viable microbial populations. The results showed a strong dependence on cultivar and by-product type, with total phenolics ranging from 2562.35 to 6304.35 mg GAE/100 g in peels and 212.69 to 3006.48 mg GAE/100 g in seeds. LC–MS profiles were dominated by gallotannin-related compounds and phenolic acids. Extracts displayed antioxidant activity (DPPH: 221.97–456.31 mg Trolox/100 g in peels; 43.71–530.46 mg Trolox/100 g in seeds) and dose-dependent antibacterial effects, with inhibition at 700 mg/L reaching 87.57–94.75%. Digestion markedly modulated phenolic-related indices and fermentation-associated metabolites, with peel phenolics decreasing from 284.27 to 73.95 mg GAE/L and seed extracts increasing propionic acid production up to 55.46 mM. Overall, mango peel and seed are differentiated, cultivar-sensitive sources of bioactive extracts with antioxidant and antimicrobial functionality and measurable impacts on colonic fermentation, supporting their use as sustainable ingredients for circular-economy food and nutraceutical applications.

This study was performed to evaluate different by-products of broccoli ( Brassica oleracea var. italica) production (leaf, inflorescence and stem) as sources of valuable bioactive compounds, considering different cultivars and states of maturation. The total phenolic and chlorophyll contents as well as the antioxidant, ACE-inhibitory and antimicrobial activities were quantified from the ethanolic extracts of the different broccoli tissues at two different maturation stages from five cultivars (TSX 007, ‘Monaco’, BRO 2047, ‘Parthenon’ and ‘Summer purple’). The major compounds in ethanolic extracts were identified by HPLC-UV-ESI-MS/MS, whereas chlorophylls were determined by UV-vis spectrometry. The leaf extracts showed the highest antioxidant activities and were the best sources of chlorophylls and phenolic compounds, constituting mainly kaempferol and quercetin glucosides. These compounds were more abundant in extracts from the ‘Sumer Purple’ variety and commercial state. Glucosinolates were more abundant in the inflorescence extracts, principally in the flower bud state. The stem and inflorescence extracts, mainly from the ‘TSX 007’ variety, showed a strong inhibitory effect on the three bacteria studied ( Bacillus cereus , Staphylococcus aureus and Listeria innocua ), which was related to a higher concentration of fatty acid derivates. The findings suggest that broccoli by-products are useful and value-added products as sources of bioactive compounds, providing a sustainable alternative to reduce residues from this crop.