Francisco A. Tomás-Barberán

Bio: Francisco A. Tomás-Barberán is an academic researcher from Spanish National Research Council. The author has contributed to research in topics: Ellagic acid & Urolithin. The author has an hindex of 106, co-authored 389 publications receiving 36505 citations. Previous affiliations of Francisco A. Tomás-Barberán include Consiglio per la ricerca e la sperimentazione in agricoltura & University of Salamanca.

Antioxidant activity of pomegranate juice and its relationship with phenolic composition and processing

Abstract: The antioxidant activity of pomegranate juices was evaluated by four different methods (ABTS, DPPH, DMPD, and FRAP) and compared to those of red wine and a green tea infusion. Commercial pomegranate juices showed an antioxidant activity (18-20 TEAC) three times higher than those of red wine and green tea (6-8 TEAC). The activity was higher in commercial juices extracted from whole pomegranates than in experimental juices obtained from the arils only (12-14 TEAC). HPLC-DAD and HPLC-MS analyses of the juices revealed that commercial juices contained the pomegranate tannin punicalagin (1500-1900 mg/L) while only traces of this compound were detected in the experimental juice obtained from arils in the laboratory. This shows that pomegranate industrial processing extracts some of the hydrolyzable tannins present in the fruit rind. This could account for the higher antioxidant activity of commercial juices compared to the experimental ones. In addition, anthocyanins, ellagic acid derivatives, and hydrolyzable tannins were detected and quantified in the pomegranate juices.

Flavonoids in Food and Their Health Benefits

Abstract: There has been increasing interest in the research of flavonoids from dietary sources, due to growing evidence of the versatile health benefits of flavonoids through epidemiological studies. As occurrence of flavonoids is directly associated with human daily dietary intake of antioxidants, it is important to evaluate flavonoid sources in food. Fruits and vegetables are the main dietary sources of flavonoids for humans, along with tea and wine. However, there is still difficulty in accurately measuring the daily intake of flavonoids because of the complexity of existence of flavonoids from various food sources, the diversity of dietary culture, and the occurrence of a large amount of flavonoids itself in nature. Nevertheless, research on the health aspects of flavonoids for humans is expanding rapidly. Many flavonoids are shown to have antioxidative activity, free-radical scavenging capacity, coronary heart disease prevention, and anticancer activity, while some flavonoids exhibit potential for anti-human immunodeficiency virus functions. As such research progresses. further achievements will undoubtedly lead to a new era of flavonoids in either foods or pharmaceutical supplements. Accordingly, an appropriate model for a precise assessment of intake of flavonoids needs to be developed. Most recent research has focused on the health aspects of flavonoids from food sources for humans. This paper reviews the current advances in flavonoids in food, with emphasis on health aspects on the basis of the published literature, which may provide some guidance for researchers in further investigations and for industries in developing practical health agents.

Phenolic compounds and related enzymes as determinants of quality in fruits and vegetables

Abstract: Phenolic secondary metabolites play an important role in plant-derived food quality, as they affect quality characteristics such as appearance, flavour and health-promoting properties. Their content in foods is affected by many factors that influence phenolic stability, biosynthesis and degradation. In terms of their biosynthesis the key enzyme phenylalanine ammonia-lyase (PAL) is especially relevant, as it can be induced by different stress (environmental) conditions. In addition, polyphenol oxidases (PPO) and peroxidases (POD) are the main enzymes responsible for quality loss due to phenolic degradation. The different factors affecting phenolic-related food quality are reviewed. These include internal (genetic) and environmental (agronomic) factors, technological treatments applied during postharvest storage of fruits and vegetables, as well as processing and storage of the processed products. The different strategies that are required to either maintain or enhance the phenolic-related quality of foods are critically reviewed. Genetic modification designed to decrease polyphenol oxidases or peroxidases is not always a feasible method, owing to side problems related to the growth and defence of the plant. Agronomic treatments can be used to enhance the phenolic content and pigmentation of fruits and vegetables, although the information available on this topic is very scarce and even contradictory. Some postharvest treatments (cold storage, controlled or modified atmospheres, etc) can also improve phenolic-related quality, as well as new processing methods such as irradiation (gamma, UV), high-field electric pulses, high hydrostatic pressures and microwaves. Les composes phenoliques, metabolites secondaires des plantes, jouent un role dans la qualite des fruits, au niveau de l'apparence, de la flaveur et des qualites nutritives. L'enzyme cle de leur biosynthese est la phenylalanine ammonium-lyase, regulee par les facteurs environnementaux. La polyphenol oxydase et la peroxydase sont responsables des degradations donc des pertes de qualite. Les differents facteurs internes (genetiques) et externes (agronomiques) affectant la qualite des produits vegetaux sont etudies. Les differentes mesures envisageables (modification genetique, traitements chimiques ou physiques apres recolte) pour modifier le contenu en compose phenoliques et donc la qualite des produits vegetaux sont etudies.

Interaction between Phenolics and Gut Microbiota: Role in Human Health

Abstract: Dietary phenolic compounds are often transformed before absorption. This transformation modulates their biological activity. Different studies have been carried out to understand gut microbiota transformations of particular polyphenol types and identify the responsible microorganisms. Although there are potentially thousands of different phenolic compounds in the diet, they are typically transformed to a much smaller number of metabolites. The aim of this review was to discuss the current information about the microbial degradation metabolites obtained from different phenolics and their formation pathways, identifying their differences and similarities. The modulation of gut microbial population by phenolics was also reviewed in order to understand the two-way phenolic-microbiota interaction. Clostridium and Eubacterium genera, which are phylogenetically associated, are other common elements involved in the metabolism of many phenolics. The health benefits from phenolic consumption should be attributed to their bioactive metabolites and also to the modulation of the intestinal bacterial population.

Antioxidant capacities, phenolic compounds, carotenoids, and vitamin C contents of nectarine, peach, and plum cultivars from California.

Abstract: Genotypic variation in composition and antioxidant activity was evaluated using 25 cultivars, 5 each of white-flesh nectarines, yellow-flesh nectarines, white-flesh peaches, yellow-flesh peaches, and plums, at the ripe (ready-to-eat) stage. The ranges of total ascorbic acid (vitamin C) (in mg/100 g of fresh weight) were 5−14 (white-flesh nectarines), 6−8 (yellow-flesh nectarines), 6−9 (white-flesh peaches), 4−13 (yellow-flesh peaches), and 3−10 (plums). Total carotenoids concentrations (in μg/100 g of fresh weight) were 7−14 (white-flesh nectarines), 80−186 (yellow-flesh nectarines), 7−20 (white-flesh peaches), 71−210 (yellow-flesh peaches), and 70−260 (plums). Total phenolics (in mg/100 g of fresh weight) were 14−102 (white-flesh nectarines), 18−54 (yellow-flesh nectarines), 28−111 (white-flesh peaches), 21−61 (yellow-flesh peaches), and 42−109 (plums). The contributions of phenolic compounds to antioxidant activity were much greater than those of vitamin C and carotenoids. There was a strong correlation...

Standardized Methods for the Determination of Antioxidant Capacity and Phenolics in Foods and Dietary Supplements

Abstract: Methods available for the measurement of antioxidant capacity are reviewed, presenting the general chemistry underlying the assays, the types of molecules detected, and the most important advantages and shortcomings of each method. This overview provides a basis and rationale for developing standardized antioxidant capacity methods for the food, nutraceutical, and dietary supplement industries. From evaluation of data presented at the First International Congress on Antioxidant Methods in 2004 and in the literature, as well as consideration of potential end uses of antioxidants, it is proposed that procedures and applications for three assays be considered for standardization: the oxygen radical absorbance capacity (ORAC) assay, the Folin-Ciocalteu method, and possibly the Trolox equivalent antioxidant capacity (TEAC) assay. ORAC represent a hydrogen atom transfer (HAT) reaction mechanism, which is most relevant to human biology. The Folin-Ciocalteu method is an electron transfer (ET) based assay and gives reducing capacity, which has normally been expressed as phenolic contents. The TEAC assay represents a second ET-based method. Other assays may need to be considered in the future as more is learned about some of the other radical sources and their importance to human biology.