Search

The proximate composition, total phenolics, antioxidant activity, minerals, and trace elements were determined in 42 barley landraces in order to highlight their nutritional potential and promote their cultivation. Two-row barley landraces had a higher average content of starch, protein, total phenolic compounds, and iron, when compared with six-row ones that presented higher mean ash and fiber concentrations. Additionally, the six-row barley landraces with strongly pigmented grains had lower zinc and manganese and higher protein mean concentrations than the whitish or lightly pigmented barley landraces. Factor analysis and linear discriminant analysis were used to correctly differentiate samples according to type of barley (landrace or commercial) and number of rows. In general, all the parameters varied considerably among the barley landraces analyzed, but some barley landraces could be emphasized according to fiber, minerals, and phenolic antioxidants. There were important differences in the mean values in all the chemical parameters according to the island of origin of the barley grains. The application of linear discriminant analysis was also a useful tool to differentiate all the barley landraces with six rows according to the island of origin. PRACTICAL APPLICATION: Barley is a versatile cereal that can be used for human and animal feed, brewing, and as biodiesel. From the nutritional point of view, barley is rich in starch, protein, dietary fiber and minerals, as well as antioxidant compounds and vitamins. The landraces analyzed in this study have remained intact for the last 900 years, which gives opportunity to genome of these barley landraces to evolve some very specific traits. The physicochemical characterization of these local landraces carried out by us could be very useful as a source of new quality in breeding programs.

Copigmentation and enological parameters were studied in a collection of 250 red wines. Although several copigmentation studies have been performed with model solutions, little is known about the actual consequences directly in wine of anthocyanin interactions. To date, some studies have considered relationships between copigmentation and natural wine constituents, but none correlates copigmentation measurements with the real wide concentration in wine. In this work, published hypotheses based on model solutions such as phenolic acid copigmentation ability or the influence of copigmentation factors such as flavonols are empirically evaluated in a large sample of wines for the first time. The study confirms previous results obtained from solutions, whereas other factors suggested as being relevant seem to be unrelated to the studied effect at the concentration range naturally occurring in the wines studied. For instance, the important role of flavonols and hydroxycinnamic acids has been ratified, whereas ethanol, gallic acid, and some metals show significant inverse correlations with copigmentation. Unexpectedly, magnesium content in wine correlates with color, whereas the concentration of traditional copigments, such as quercetin, does not show any correlation with copigmentation.

Proximate composition (moisture, protein, starch, amylose, total dietary fibre, Brix degree, fat, ash, ascorbic acid, phenolic compounds, acidity and pH), minerals (Na, K, Ca, Mg) and trace elements (Fe, Cu, Mn, Zn) were determined in 30 cultivars of sweet potato from the Canary Islands (Spain). There were significant differences between the sweet potato cultivars for all the parameters studied; in addition, both the island of production and the cultivation cycle showed a noteworthy influence on the mineral and trace element composition of the tubers. It is worth mentioning that the consumption of sweet potatoes contributes relatively high intake levels of vitamin C, phenolic compounds and mineral and trace elements (K, Mg, Ca, Mn, Fe and Cu). Application of multidimensional scaling (MDS) correctly classified the sweet potato cultivars according to the island of production and maturation cycle.

Physicochemical, sensory and microbiological quality parameters were determined in fresh-cut pineapple products. Containers with fresh-cut pineapple in cylinders or in chunks were considered and the above parameters were studied over ten days of storage at 5 ± 1 °C. Chromatic parameters presented differences between both formats, with the cylinders being more susceptible to browning. Besides, the cylinders had lower levels of acidity, texture and ascorbic acid, while in general, greater changes of the main quality physicochemical characteristics were observed in the ring format during the ten days of refrigerated storage. Liquid exudate increased, sucrose content decreased and a greater tendency to browning were observed during the cold storage at 5 ± 1 °C. Sensory characteristics and microbiological control for both types of format showed a positive evaluation after eight days of storage at 5 ± 1 °C. Mesophile, psychrophile, mold and yeast loads in both pineapple formats were relatively low (

A hundred and thirty-six single-cultivar red wines of different vintages were collected from several wineries in the Canary Islands in order to study the magnitude of the copigmentation phenomenon and the antioxidant activity. The contribution of free anthocyanins, copigmented anthocyanins and polymeric pigments to the colour of wine, as well as the total phenols, the antioxidant activity (2,2-diphenyl-1-picrylhydrazyl, DPPH method) and the chromatic characteristics of the wines were determined. The influence of ageing time and the climatic conditions on these parameters was also studied. The wines made with Merlot, Ruby Cabernet and Syrah cultivars showed the highest parameters of colour, and the largest contribution to the copigmented anthocyanins was from the Ruby Cabernet, Listan negro and Syrah cultivars. The copigmented anthocyanins and the free anthocyanins decrease with the age of the wine, and the antioxidant activity of the samples appears to be related to the total phenol content. An influence of the climatic conditions on colour parameters has been found. The correlation study between parameters suggests that the parameters b* and L* could be used as suitable indicators of evolution or oxidation stage of red wines.

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.

Moisture, starch, amylose, fibre, proteins, ascorbic acid, total phenol compounds, acidity, pH, ash and mineral and trace elements were determined in 10 potato cultivars from Canary Islands experimentally cultivated. Six of the cultivars were also cultivated in two locations, to ascertain the impact of different soil types on the parameters measured. There were differences between cultivars in both, physicochemical parameters and mineral and trace elements analysed. There were significant differences in the mean values obtained for all the parameters considered, except for ascorbic acid, between both locations. Application of linear discriminant analysis allowed to classify the potato samples according to the cultivar, and according to growing location.

Summary Organic acids, pH and total acidity were determined in the grains of nineteen wheat cultivars. Six organic acids, such as glutamic, oxalic, malic, tartaric, shikimic and fumaric acids, were separated and identified in all wheat samples applying HPLC coupled to diode array detector. Glutamic acid was the major organic acid followed by tartaric and malic acids. A low oxalic acid/calcium ratio was observed in the wheat samples analysed. The wheat samples belonging to Triticum turgidum had a higher (P

In order to study interactions between agronomic variables and chemical composition that determine the quality of tomato fruits, a group of statistical techniques were applied: discriminant analysis (DA), cluster analysis (CA) and princepal component analysis (PCA) combined with ANOVA. The results of DA when characterizing the agronomic parameters were successful, especially when the collection date was used as a factor for classification. CA showed the importance of the chemical variables related to the metabolic relationships, while the principal component analysis and ANOVA provide information on the interaction between variables related to the production and chemical composition of tomatoes. The combined use of PCA and ANOVA is a suitable tool for studying the complex interactions between agronomy and chemical composition. Collection date was the main agronomic parameter effected the chemical composition, while variety and production system had a minor effect. The application of PCAANOVA showed that the taste of tomato depends on three factors: sugars (glucose and fructose), acidity (citric, malic and ascobirc acids), and minerals (Na and Mg). For the tomatoes with same maturity degree, the taste depends on interaction of date collection and system production.

The main scientific discoveries on Aloe vera published mainly in the last three decades are presented in this work. After describing Aloe from a botanical point of view, the papers related with the chemical composition of different parts of the leaf of Aloe, particularly those in which the gel is described and are presented in a synthetic manner. The chemical analyses reveal that Aloe gel contains mannose polymers with some glucose and other sugars, among which the most important is Acemannan. Besides these, other components such as glycoproteins, enzymes, amino acids, vitamins, and minerals are described. Different factors also affecting the chemical composition of the gel, such as species and variety, climatic and soil conditions, cultivation methods, processing and preservation, are enumerated and discussed. On the other hand, the main therapeutic applications have been revised and the possible damaging effects of Aloe are also commented upon. A special emphasis is placed on the biologically active compounds or groups of compounds responsible for the therapeutic applications and which are their action mechanisms. The paper concludes that more research is needed to confirm the therapeutic and beneficial effects and to definitively clarify the myth surrounding Aloe vera. A general view on the problem of the commercialization and establishment of the quality and safety of Aloe products in the food industry has been offered here. The main points and European regulations that need to be considered regarding the quality control of prepared Aloe products are presented in this paper.

The following organic acids (glutamic, oxalic, pyruvic, malic, tartaric, citric, and fumaric), pungency, Brix degree, acidity, and pH were determined in onion cultivars (Texas, Guayonje, San Juan de la Rambla, Carrizal Alto, Carrizal Bajo, and Masca) harvested in the same agroclimatic conditions. Glutamic acid was the most abundant organic acid (325 +/- 133 mg/100 g) followed by citric acid (48.5 +/- 24.1 mg/100 g) and malic acid (43.6 +/- 10.4 mg/100 g). There were significant differences between the onion cultivars in the mean concentrations of all of the analyzed parameters. The San Juan de la Rambla and Masca cultivars presented, in general, higher concentrations of the organic acids than the other cultivars. Significant differences in most of the analyzed parameters were observed between the two seed origins for the Masca and San Juan de la Rambla cultivars. The onion samples tended to be classified according to the cultivar and, in the case of San Juan de la Rambla cultivar, according to the precedence of the seeds after applying discriminant analysis.

Chestnuts like other foodstuffs may be characterized by their chemical composition. The chemical composition of ascorbic acid, total acidity, pH, starch, refraction index (°Brix), moisture, ashes, insoluble fibre, soluble fibre, total dietary fibre, total proteins, cations (Na, K, Ca, Fe, Cu, Zn, Mn, Mg) and phosphorous was determined in 19 local chestnut varieties from three areas of production in the island of Tenerife. Significant differences were found between the mean values of moisture, starch, total phenols contents, total soluble and non-soluble fibre, Ca, Cu, K, Mg and Zn, obtained according to the area of production. Distribution patterns of the samples were established for correlating the chemical composition of the chestnuts and varieties, using different chemometrics tools such as cluster analysis, principal component analysis, factor analysis and linear discriminant analysis (LDA). Initially, cluster analysis made it possible to establish a primary relationship between the variables. When applying stepwise LDA the chestnut samples were well classified within their area of production. Also, when the stepwise LDA was used on the chestnut samples from area of production 2, 100% of the chestnut samples were also correctly classified within their variety.

In the Canary Islands there are some lesser-known varieties of white grapes. The aim of this study is to examine the differences in phenolic compounds and colour coordinates between three varietal white wines, Listan blanco, Verdello and Gual, cultivated in a very special region due to its location and its low irrigation. Using a HPLC method, we have measured 19 compounds of different phenolic groups. The wines of this study presented high values of these compounds. The Gual variety had the highest significant values of the cis and trans-resveratrol, trans-piceid and total resveratrol content with an average of 3.94 mg/L. The ratio of trans-coutaric acid/trans-caftaric acid concentration allowed the differentiation also of Gual variety. Furthermore, caftaric acid has been shown to be a chemotaxonomic parameter for white wines.

A simple reversed-phase high-performance liquid chromatographic method was developed for the determination of theobromine, theophylline and caffeine in cocoa samples. In the sample cleanup step, the procedure involves an on-line solid-phase extraction of analytes from cocoa samples into a home-made dry-packed pre-column with ODS-C 18 using a column-switching system. The separation was performed on a C 18 Nova-Pak column (150 mm × 3.9 mm, 4 μm) using a mobile phase consisting of a solution of 20% of methanol in water under isocratic conditions, at a flow-rate of 1.4 ml/min. The validation method revealed quantitative recoveries (>95.0%) with a coefficients of variation

The biochemical and haematological parameters of nutritional interest were determined in the serum of opiate addicts in order to compare them with those obtained in healthy subjects. The blood of 106 opiate addicts in detoxification treatment (n=19) or in Methadone Maintenance Treatment Program (MMTP) (n=87) was studied. Opiate addicts presented lower levels in the number of red cells, cholesterol, albumin, retinol, α-tocopherol, folic acid, K and Se and higher levels in the number of leukocytes, GOT, GPT and Na, than the control group. The opiate addicts in MMTP had higher levels of glucose, triglycerides, Mg and P than the opiate addicts in the detoxification treatment and control groups. Significant correlations between the three vitamins (folic acid, retinal and α-tocopherol) were observed and the graphic representations suggest a biochemical differentiation between opiate addicts and healthy subjects. Factor analysis made it possible to select seven factors explaining 66.2% of the total variance, and representing the first and fourth factor, opiate addicts tended to separate from the control group.

A comparative study of three methods for titrable acidity determination in must and wines was carried out. Titrable acidity (TA) was analysed in 115 wines from the Canary Islands by conductance titration, AOAC and OIV procedures. Conductivity, pH, malic acid, tartaric acid and potassium content were also determined. The results of TA obtained depended on the method used, however, a highly significant correlation between these methods was found. Conductance titration showed that the true end point is in pH values higher than those of the AOAC and OIV procedures. In order to compare the results of TA obtained in different countries by AOAC and OIV procedures, the use of some expressions, one for red wine and one for white wine, is proposed. An important differentiation between red and white wine mean discrimination analysis using pH values, malic acid and potassium content could be observed.

Determination of free gallic acid and catechin (cianidanol) in banana samples was optimized using a high-performance liquid chromatographic (HPLC) method with on-line photodiode array detection. This method was applied for cultivars of bananas (Gran Enana and Pequena Enana) harvested in Tenerife (Canary Islands) and for bananas (Gran Enana) from Ecuador. The contents of catechin and gallic acid in bananas from Ecuador were higher (P

The evolution of moisture, starch, amylose, ash, fructose, sucrose, glucose and ascorbic acid was studied in five cultivars of Tenerife potatoes in order to evaluate their variation during storage at 12 °C and 90% humidity. Differences in behaviour were detected among cultivars in relation to the period of storage under these conditions. The Negra cultivar presented the worst behaviour in storage, while the Bonita and Colorada cultivars presented the best. The moisture remained constant for the first 6 weeks; afterwards; a significant decrease was observed. A progressive decrease of starch (dry basis) over the time of storage was detected, while an increase of reducing sugars occurred. The amylose/amylopectin ratio increased during the first 6 weeks of storage. The concentration of vitamin C decreased markedly during the storage, and, after the 20th week, the content had decreased by more than 50%.

The copigmentation effect of prefermentation additions of different doses of caffeic acid was investigated during the 1997 harvest. Microfermentation with the major red grape cultivars Listán negro and Negramoll, grown in the Canary Islands, was carried out with the same protocol. Visible and UV spectra were registered periodically. HPLC chromatograms were carried out. The color enhancement of cv. Negramoll wine varied between 13 and 75% (AU at 520 nm), and that of cv. Listán negro wine between 25 and 45% at the end of fermentation. During aging these values were enhanced to reach even100% in some cases. An initial complex of the 1:1 type, where one molecule of caffeic acid associates with one molecule of anthocyanin, has been identified using the mathematical procedure of Brouillard et al. (J. Am. Chem. Soc. 1989, 111, 2604-2610). Caffeic acid seems to contribute to color stability and protection against oxidation. The importance of nonpigment composition in pigment extraction and color retention during and after fermentation is demonstrated.

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

Urinary selenium (Se) concentrations (μg/1 of urine and μg/g of creatinine) and urinary Se excretions (μg/d and μg/d • kg of body weight) have been determined in healthy Canarian people. Urinary Se status was relatively low and similar to those data published from European regions. Females excreted daily significantly (P = 0.005) higher amounts of Se per kg of body weight in urine than males. An increase of daily urinary Se excretion was observed up to 30 years of age. Children (μ 10 years old) had daily urinary Se excretion per kg of body weight higher than persons with age > 10 years old. Both units of Se excretion, μg/d and μg/d • kg, increased or decreased respectively with weight and height of the individuals. Food habits such as consumption of rich protein or rich fibre food, and drinking alcohol or coffee as well as smoking do not seem to influence the urinary Se status. Depletion of daily urinary Se excretion was observed with the increase of physical exercise. Unit of concentration (μg/g of creatinine) is a more adequate indicator of the urinary Se excretion than the unit μg/1. © 1995, Walter de Gruyter. All rights reserved.

Determination of free phenolic compounds in potato samples was optimized using a high-performance liquid chromatographic (HPLC) method with on-line diode array detection. This method was applied to samples of four cultivars of potatoes harvested in Tenerife (Canary Islands). The free phenolic compounds found in the potato samples were (+)-catechin, chlorogenic acid, caffeic acid, p-coumaric acid, and ferulic acid. Potato samples belonging to Colorada cultivar, ssp. andigena, had mean concentrations of total phenolic compounds and chlorogenic acid higher than those found for Kerr's Pink and Cara cultivars, ssp. tuberosum, and for Negra cultivar, S. x chaucha. In contrast, p-coumaric acid was not detected in any potato samples of the Colorada cultivar. Traditional potatoes presented a higher mean concentration of ferulic acid than recently imported potatoes. A significant and negative correlation was established between (+)-catechin and p-coumaric acid. A considerable contribution to the daily intake of flavonoids was observed with the actual consumption of potatoes.