Carlos Díaz Romero

Background: Beans constitute one of the most important grain legume species from the socioeconomic point of view, playing an essential role in a sustainable agriculture and food safety and nutrition. In fact, beans contain a rich diversity in nutrients, highlighting their high protein, starch and fiber content. Canary Islands have a considerable diversity of beans, including three of the five cultivated species of Phaseolus: P. coccineus, P. lunatus and P. vulgaris, the latter being the most cultivated. Methods: Proximate composition, total phenolics, pH, acidity, minerals and trace elements were determined in 23 common bean accessions (P. vulgaris) in order to find out their nutritional potential and promote their cultivation. Result: Parameters found fell well into the ranges of the data described in the literature for beans. The consumption of beans contributes remarkedly to the daily intake of protein (although is deficient in sulfur amino-acids), fiber, phenolic compounds, minerals such as Mg and K and trace elements as Fe (although with low bioavailability), Cu and Mn. Phenolic compounds in beans increases when pH decreased and acidity increased. Protein content was positively correlated with trace elements content, except Se. Color of the seed influenced on content protein, starch, fiber, P, K, Mg, Fe, Cu and Zn, while shape only affected on starch, fiber, P and K.

Proximate composition was determined in 19 wheat cultivars from the Canary Islands in order to establish differences between them and contribute to their characterization. All parameters analysed showed significant differences between cultivars; and also many parameters were affected by the species and subspecies of wheat. Triticum aestivum had higher mean moisture, protein, and fibre and lower mean starch, sucrose, and amylose concentrations than Triticum turgidum. Low starch content and high fibre content could be due to the transformation of starch into resistant starch during desiccation process. An important contribution of complex carbohydrates, including fibre as well as protein and phenolic compounds, was observed for the consumption of wheat.

Wines from the Atlantic Islands of Macaronesia come from unusual terroirs due to their volcanic soils and the tropical and subtropical climatic conditions from this region. Some of these Islands produce highly appreciated fortified wines traded around the world since the sixteenth century, such as Madeira or Canary. Nowadays their distinct winemaking techniques and sweet wine traditions combine with the production of table wines. Previous studies described peculiar properties in wines from these regions, mostly related with their phenolic content and color, which are particularly important in the less produced red wines. The main purpose of this chapter is to characterize red wines produced in the Atlantic Islands of Macaronesia in terms of oenological and physico-chemical properties. Wines from these islands are extremely atypical, as their climates conditions are exceptional and red grape cultivars are exclusive. Furthermore, specific viticulture techniques are applied in these latitudes to proportionate the unique characteristics outlined in this work. Original experimental data from 300 red wines produced in 8 Atlantic islands from Canary and Cape Verde archipelago and an important reviewing study for Azores and Madeira red wines are considered herein. Results are presented according to archipelago.

Tomatoes have been described as a functional food because of their particular composition of different bioactive compounds. In this study, the proximate composition, minerals and trace elements, and antioxidant compounds were determined in two tomato cultivars (Mariana and Dunkan) that were grown in Gran Canaria (Spain) either conventionally or hydroponically. Although compositional data of this type require being subjected to the specific statistical techniques of compositional analysis, this approach has not usually been considered in this context. In the present case, a compositional Mann–Whitney U test of the data showed significant differences for each factor (cultivar and cultivation system) in several of the compositional variables studied. For the differences between cultivars, these parameters were the protein, Mg, lycopene, ascorbic acid, citric acid, and fumaric acid contents. For the differences between cultivation systems, they were mainly those of the mineral and trace elements group. Although one-year data are insufficient to make clear relationship among compounds because more repetitions in several localities and years are necessary, the compositional HJ-biplot (in which the links provide estimates of the linear relationship among variables) results agreed with other scientific results about linear relationship among some compounds analyzed.

Three hydroxybenzoic acids: p-hydroxybenzoic acid, vanillic acid and syringic acid; six hydroxycinnamic acids: p-coumaric acid, ferulic acid and four ferulic acid derivatives and a flavonoid (apigenin) were identified and quantified in 34 accessions corresponding to 19 cultivars of wheat applying HPLC coupled to diode array detector. Considerable differences between the wheat cultivars were observed in the phenolic contents. Some cultivars (Colorado, Del País, Barbilla, Jallado, Raspinegro Canario and Plaganudo) could be selected according to the high levels of phenolic compounds. Ferulic acid was the major phenolic acid compound followed by syringic and p-hydroxybenzoic acids. The proportion of ferulic acid present as dimeric forms ranged from 4.2 to 8.6% across all of the wheat cultivars analyzed. Apigenin, p-hydroxybenzoic and syringic acids did not show significant correlations. Many correlations between the determined hydroxycinnamic acids were observed. The ferulic acid and all the ferulic acid derivatives showed highly significant correlations, suggesting that the concentrations of diferulic acids depend on the concentration of ferulic acid.

The contents of vitamin C (ascorbic and dehydroascorbic acids) and other organic acids such as citric, oxalic, fumaric, malic and glutamic, were determined by HPLC in 54 samples of tomato, white onion, cucumber, pepper, garlic, and “gazpacho” elaborated using the previous vegetables. Tomato and garlic had the highest amounts of organic acids, while cucumber presented the lowest content. Citric and glutamic acids presented the highest mean concentrations. The bulb vegetables presented higher concentrations of glutamic and citric acids than the fruit vegetables. Pepper was the vegetable with the highest content of vitamin C, followed by tomato and “gazpacho”. Mean value of ascorbic acid/dehydroascorbic acid ratio varied between 0.29 and 2.53 for cucumber and tomato, respectively. “Gazpacho” samples had a lower ascorbic acid/dehydroascorbic acid ratio than the vegetables used in its elaboration, which suggests that some amount of ascorbic acid may be enzymatically oxidized to dehydroascorbic during the elaboration. Se determinaron los contenidos de vitamina C (ácidos ascórbico y deshidroascórbico) y otros ácidos orgánicos como cítrico, oxálico, fumárico, málico y glutámico, por HPLC, en 54 muestras de tomate, cebolla blanca, pepino, pimiento, ajo y “gazpacho” elaborado a partir de estos vegetales. Tomate y ajo fueron los que presentaron mayores contenidos de ácidos orgánicos, mientras que en pepino se encontró el menor contenido. Los ácidos orgánicos mayoritarios fueron cítrico y glutámico. Los bulbos presentaron las mayores concentraciones de ácidos glutámico y ácido cítrico de los frutos. El pimiento fue el vegetal que presentó los mayores contenidos de vitamina C, seguido de tomate y “Gazpacho”. La relación entre ácido ascórbico/ácido dehidroascórbico osciló entre 0,29 y 2,53 para pepino y tomate, respectivamente. Las muestras de “gazpacho” mostraron una relación ácido ascórbico/ácido dehidroascórbico inferior al de los vegetales usados en su elaboración, lo que sugiere que una cierta cantidad de ácido ascórbico se oxida enzimáticamente a dehidroascórbico durante su elaboración.

BACKGROUND: Citric, malic, tartaric, oxalic, ascorbic, aconitic and fumaric acids, and sucrose, fructose and glucose, were determined in ten potato cultivars (Azucena negra, Bonita, Bonita negra, Borralla, Colorada de baga, Mora, Negra, Palmera lagarteada, Peluca blanca and Terrenta) from the Canary Islands in order to differentiate them. The influence of the production zone was also considered.RESULTS: Citric acid and sucrose were the most abundant organic acid and sugar, respectively. There were significant differences in all the analysed sugars and organic acids between the potato cultivars, except for oxalic and malic acids. Differences associated with the production zone were found in the contents of organic acids for some cultivars. Linear discriminant analysis is a useful tool to differentiate the potato samples according to the cultivar and the zone of production.CONCLUSIONS: Seven organic acids (citric, oxalic, malic, tartaric, aconitic, fumaric, and ascorbic acids) were identified and quantified in potatoes. The main sugars (sucrose, glucose and fructose) were also determined. The genetic information of the cultivars determines marked differences in sugars and organic acid contents among the analysed potato cultivars. The soil and climatic conditions affect the organic acid and sugar contents of some potato cultivars. Copyright © 2010 Society of Chemical Industry

ABSTRACT:  Total phenol and flavonoid contents were analyzed by HPLC coupled with a diode array detector in 5 traditional onion cultivars from Tenerife (Guayonje, San Juan de la Rambla, Carrizal Alto, Carrizal Bajo, and Masca) and a commercial cultivar (Texas Early Grano 502). Five quercetin chemical species (isoquercetin, quercetin diglucoside, quercetin monoglucoside 1, quercetin monoglucoside 2, and free quercetin) and kaempferol were identified and quantified in the onion samples. Quercetin monoglucoside 1 and quercetin diglucoside were the major flavonoids accounting for 80% of the total quercetin content. The mean quercetin monoglucoside 1: quercetin diglucoside ratio (QMG/QDG) was 1: 2.2. There were differences between the onion cultivars in the cases of total phenol, quercetin diglucoside, isoquercetin, QMG/QDG ratio, and kaempferol. The Texas cultivar had a higher QMG/QDG ratio and a higher kaempferol content than the traditional cultivars. The correlation study showed significant correlations between the analyzed phenolic components.