Percorrer por autor "Prieto, Miguel A."
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- Grape Winemaking By-Products: Current Valorization Strategies and Their Value as Source of Tannins with Applications in Food and FeedPublication . Echave, Javier; González Pereira, Antía; Jorge, Ana O. S.; Barciela, Paula; Nogueira-Marques, Rafael; Yuksek, Ezgi N.; Oliveira, María B. P. P.; Barros, Lillian; Prieto, Miguel A.Grape (Vitis vinifera L.) is one of the most extensively cultivated crops in temperate climates, with its primary fate being wine production, which is paired with a great generation of grape pomace (GP). GP contains a plethora of antioxidant phenolic compounds, being well-known for its high content of various tannins, liable for the astringency of this fruit. Winemaking produces a great mass of by-products that are rich in tannins. Grape seed (GSd) and pulp waste, as well as leaves and stems (GSt), are rich in condensed tannins (CTs), while its skin (GSk) contains more flavonols and phenolic acids. CTs are polymers of flavan-3-ols, and their antioxidant and anti-inflammatory properties are well-accounted for, being the subject of extensive research for various applications. CTs from the diverse fractions of grapefruit and grapevine share similar structures given their composition but diverge in their degree of polymerization, which can modulate their chemical interactions and may be present at around 30 to 80 mg/g, depending on the grape fraction. Thus, this prominent agroindustrial by-product, which is usually managed as raw animal feed or further fermented for liquor production, can be valorized as a source of tannins with high added value. The present review addresses current knowledge on tannin diversity in grapefruit and grapevine by-products, assessing the differences in composition, quantity, and degree of polymerization. Current knowledge of their reported bioactivities will be discussed, linking them to their current and potential applications in food and feed.
- Phytochemical diversity and biological activities of Hypericum japonicum and Hypericum sampsonii: potential for natural product-based food applicationsPublication . Barciela, Paula; Rodrigues, Daniele B.; Perez-Vazquez, Ana; Silveira, Tayse F. F. da; Pires, Tânia C.S.P.; Mandim, Filipa; Carpena, Maria; Pereira, Carla; Ferreira, Isabel C.F.R.; Barros, Lillian; Prieto, Miguel A.This study characterizes two species of the genus Hypericum to envisage their applicability as effective and versatile functional foods, dietary supplements, and food preservatives. A wide phenolic composition was found in both extracts, highlighting flanovoids for H. japonicum and xanthones for H. sampsonii. Moreover, anthocya- nins were analyzed for the first time in the latter plant. Antioxidant capacity was highlighted by oxidative he- molysis inhibition assay (OxHLIA), where H. japonicum was more effective (lower EC50) than antioxidant Trolox (16.3 < 21.8 μg/mL). H. sampsonii extract inhibited lipid peroxidation in the thiobarbituric acid reactive sub- stances (TBARS) method (EC50 = 17.05 μg/mL) compared to Trolox (EC50 = 5.8 μg/mL). H. japonicum anti- bacterial activity showed a minimum inhibitory concentration (MIC) of 0.007 mg/mL, even lower than the control. These results indicate the bioactive potential of both extracts, as well as the importance of evaluating the food-related bioactive components of medicinal plants and the mechanisms involved in their bioactivities.