Concentrations of fluoride in wines from the Canary Islands.

Potentiometry using an ion-selective electrode has widely been used for determining fluoride because of its simplicity and rapidity. The concentration of fluoride was determined (Gran's method) in 70 wines from the main wine-producing regions of the Canary Islands. The mean concentration of fluoride in wines from a region with a high concentration of fluoride in drinking waters was significantly (p < 0.05) higher than those mean concentrations obtained in the remaining wines. Non-important differences were found among the types of wine analysed. However, the fluoride concentrations of all the Canarian wines analysed here did not present a risk for the public health.     

Diversity of acetic acid bacteria present in healthy grapes from the Canary Islands

The identification of acetic acid bacteria (AAB) from sound grapes from the Canary Islands is reported in the present study. No direct recovery of bacteria was possible in the most commonly used medium, so microvinifications were performed on grapes from Tenerife, La Palma and Lanzarote islands. Up to 396 AAB were isolated from those microvinifications and identified by 16S rRNA gene sequencing and phylogenetic analysis. With this method, Acetobacter pasteurianus, Acetobacter tropicalis, Gluconobacter japonicus and Gluconacetobacter saccharivorans were identified.However, no discrimination between the closely related species Acetobacter malorum and Acetobacter cerevisiae was possible. As previously described, 16S-23S rRNA gene internal transcribed spacer (ITS) region phylogenetic analysis was required to classify isolates as one of those species. These two species were the most frequently occurring, accounting for more than 60% of the isolates. For typing the AAB isolates, both the Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR and (GTG)5-PCR techniques gave similar resolution. A total of 60 profiles were identified. Thirteen of these profiles were found in more than one vineyard, and only one profile was found on two different islands (Tenerife and La Palma).     

Determination of antioxidants in edible grain derivatives from the Canary Islands by capillary electrophoresis

A preliminary study of the antioxidant content of hand-produced grain derivatives from the Canary Islands, named gofio, is developed by means of a capillary electrophoresis (CE) method. Protocatechuic acid, salicylic acid, p-hydroxybenzoic acid, vanillic acid, syringic acid, p-coumaric acid, ferulic acid and sinapic acid were extracted from corn, wheat, barley and pea gofio samples by sonication with methanol and were successfully separated by CE using a polycation, hexadimetrine bromide (HDB), as electrosmotic flow modifier. The separation was achieved using a running buffer consisting of 125 mM boric acid, 49 mM disodium hydrogen phosphate, 0.002% (w/v) HDB and 2.5 mM α-cyclodextrin at pH 7.5. The developed procedure allowed the simultaneous determination of the selected antioxidants in less than 3.5 min. The electrophoretic profile obtained for each kind of flour (corn, wheat, barley and pea) allowed differentiation of the type of gofio. Among the analyzed samples, corn gofio showed the highest antioxidant content. Furthermore, highly roasted corn or wheat gofio samples were also analyzed and their antioxidant contents were lower than those of less roasted samples.     

Total dietary intake of mercury in the Canary Islands,Spain

Estimating the risk associated with dietary intake of heavy metals by consumers is a vital and integral part of regulatory processes. The assessment of exposure to mercury shown in this paper has been performed by means of a study on the whole diet. Total mercury (Hg) levels were determined by cold vapour atomic absorption spectrometry (AAS) in 420 samples of regularly consumed food and drink. The total Hg concentrations measured in the different groups of food ranged from non-detectable to 119 µg kg^?1 w/w. The fish group had the highest concentrations of total Hg. All groups of food with regulated Hg content showed levels that were lower than the legally set values. The food consumption data used in the analysis were taken from the latest nutritional survey made in the Canary Islands, Spain. The estimated total Hg intake of local population (5.7 µg/person day^?1) did not exceed the provisional tolerable weekly intake (PTWI) limit of 0.3 mg week^?1 of total mercury (43 µg/person day^?1) fixed by the Joint Food and Agricultural Organization/World Health Organization (FAO/WHO) Expert Committee on Food Additives. Fishery products contributed 96% of the total Hg intake. The mean Hg intake for each island in this archipelago, formed by seven, has also been calculated. Fuerteventura, Lanzarote and El Hierro are the islands with the highest level of Hg intake (7.0, 7,0 and 6.1 µg/person day^?1, respectively). La Palma Island, due to its low fish consumption, had the lowest level of Hg intake (4.5 µg/person day^?1), followed by La Gomera (5.4 µg/person day^?1), Tenerife (5.5 µg/person day^?1) and Gran Canaria (5.6 µg/person day^?1). A comparison has been made of the results obtained in this study with those found for other national and international communities.     

Fluoride levels in wines of the Canary Islands (Spain)

Fluoride content in bottled wines of the different types and areas of the Canary Islands was studied by direct potentiometry with a fluoride specific electrode using the addition method. We found a mean concentration of 0.15 mg/l and a standard deviation of 0.068. The biggest concentration of fluoride ion (0.50 mg/l) was found in a white wine of Tacoronte-Acentejo. However, all wines analyzed presented concentrations of fluoride lower than the maximum allowed by the International Office of the Vineyard and the Wine. So, the contribution of the Canarian wines to the fluoride daily intake does not represent any risk of fluorosis. Also these concentrations have no influence on the production process of the wine.     

Total dietary intake of mercury in the Canary Islands, Spain

Estimating the risk associated with dietary intake of heavy metals by consumers is a vital and integral part of regulatory processes. The assessment of exposure to mercury shown in this paper has been performed by means of a study on the whole diet. Total mercury (Hg) levels were determined by cold vapour atomic absorption spectrometry (AAS) in 420 samples of regularly consumed food and drink. The total Hg concentrations measured in the different groups of food ranged from non-detectable to 119 microg kg(-1) w/w. The fish group had the highest concentrations of total Hg. All groups of food with regulated Hg content showed levels that were lower than the legally set values. The food consumption data used in the analysis were taken from the latest nutritional survey made in the Canary Islands, Spain. The estimated total Hg intake of local population (5.7 microg/person day(-1)) did not exceed the provisional tolerable weekly intake (PTWI) limit of 0.3 mg week(-1) of total mercury (43 microg/person day(-1)) fixed by the Joint Food and Agricultural Organization/World Health Organization (FAO/WHO) Expert Committee on Food Additives. Fishery products contributed 96% of the total Hg intake. The mean Hg intake for each island in this archipelago, formed by seven, has also been calculated. Fuerteventura, Lanzarote and El Hierro are the islands with the highest level of Hg intake (7.0, 7,0 and 6.1 microg/person day(-1), respectively). La Palma Island, due to its low fish consumption, had the lowest level of Hg intake (4.5 microg/person day(-1)), followed by La Gomera (5.4 microg/person day(-1)), Tenerife (5.5 microg/person day(-1)) and Gran Canaria (5.6 microg/person day(-1)). A comparison has been made of the results obtained in this study with those found for other national and international communities.     

Phenolic profile in varietal white wines made in the Canary Islands

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, Listán 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.     

Chemical composition of tomato (Lycopersicon esculentum) from Tenerife,the Canary Islands

Chemical composition (moisture, ash, total fibre, protein, glucose and fructose), the taste index and maturity were determined in five tomato cultivars (Dorothy, Boludo, Thomas, Dominique, Dunkan) which were cultivated using intensive, organic and hydroponic methods in Tenerife. The chemical composition was similar to most of the data found in the literature. There were many significant differences in the mean values between the analysed parameters according to the cultivar, cultivation method, region of cultivation and sampling period. Glucose and fructose concentrations were strongly and positively correlated, suggesting the common origin of both sugars. The moisture correlated inversely with the rest of the analysed parameters. Applying a stepwise discriminant analysis (DA), low percentages of correct classifications were obtained according to the cultivar and cultivation methods. The correct classification of the tomato samples improved when the DA was applied to differentiate the tomatoes according to the sampling period.     

Trans-resveratrol in wines from the Canary Islands (Spain). Analysis by high performance liquid chromatography

Trans-resveratrol is a phytoalexin from grapes with interesting therapeutic properties. Thus considerable interest has been directed to its study. In this paper the determination of trans-resveratrol in wines from the Canary Islands by high performance liquid chromatography (HPLC), using absorbance and fluorescence detectors in series, is reported. The use of fluorimetic detection improves selectivity and sensitivity for the determination of this compound. The detection limits in real samples were 0.02 and 0.003 mg/l for absorbance and fluorescence detection, respectively. We compared the results obtained by means of both detectors, for 58 red wines from different denominations of origin, and no significant differences were observed, either between methods or among the denominations of origin. The mean level found in bottled red wines was 2.89 mg/l.     

Chemometric studies of bottled wines with denomination of origin from the Canary Islands (Spain)

Seventeen physicochemical parameters including conventional enological parameters, polyphenolic parameters and volatile compounds were determined in 153 wines from the main wine producers belonging to the Canarian zones with Denomination of Origin (DO). Numerous significant correlations were found between the physicochemical parameters analysed. Applying the principal component analysis, the wines tend to separate on the basis of the type of wine. Besides, the dimension space was reduced to six principal components that explain 76.1% of the total variance. The principal component analysis of the red wines separated them as a function of vintage. Linear discriminant analysis (LDA) applied to all the wines, allowed a reasonable differentiation according to vintage, type of wine and island of production.     

Comparative study of the protein fraction of goat milk from the Indigenous Greek breed and from international breeds

Individual goat milk samples, taken from animals of the Indigenous Greek breed and from the international breeds Saanen and Alpine, were studied by RP-HPLC regarding the qualitative and quantitative characteristics of their proteins. Thirty-two samples from the Indigenous Greek breed and 17 from the international breeds were characterised further by RP-HPLC/ESI-MS. The mean total protein content of the milk samples from the Greek breed was higher 38.8 g/l, compared to 31.9 g/l of those from international breeds, due to the great difference between their mean αs1-Cn contents (6.90 and 3.02 g/l, respectively). In the milk samples of the Greek breed, the strong αs1-Cn variants B3, B4 and As/B1 predominated, whereas in the milk samples from international breeds the medium variant E and the defectives F and null predominated. Variant A of αs2-Cn followed by variant C and the κ-Cn D (former B) were the most abundant in both groups. αs2-Cn F and the rare κ-Cn variant C/B were observed in the milk samples from the Greek breed. The β-caseins A and C were present in both groups of samples. Finally, the level of phosphorylation of the different genotypes is showed.     

Determinants of specific food consumption in the Canary Islands (Spain)

The consumption of specific functional foods (FF) and some determinants of FF item selection were assessed using a questionnaire administered to 1112 individuals in the Canary Islands (Spain). Food items considered were Milk products: easily digestible milk (or milk low in lactose), milk enriched with vitamins and/or minerals, skimmed milk with soluble fiber, milk with royal jelly, milk with modified fatty acids (omega 3), milk products low in fat, pro-biotic foods (yoghurt and fermented milk) and yoghurt with phytosterols; Cereals: fortified breakfast cereals, wholemeal cereals and energy bars; Drinks: juices and enriched drinks, stimulating drinks and isotonic drinks; DHA-enriched, low cholesterol eggs; Meat products: low salt sausages and cooked low fat ham; Fats: enriched margarine, margarine rich in phytosterols and sunflower oil rich in oleic acid; Condiments: iodated salt. These food items were organized into 7 FF groups (milk products, cereals, fortified drinks, DHA eggs, meat product, fats, condiments). The results indicated that the highest prevalence was fortified drinks (63.6%; 95% CI: 60.7-66.5). Overall FF consumption prevalence was 80.1% (95% CI: 77-83): single FF item consumption being rare. There were significant inter-group relationships, and some group intakes (milk products, cereals and drinks) were related to age but with no overall relationship between consumption and age. The education level was significantly related to the consumption of cereals, drinks, meat products and condiments (χ2 test p = 0.04). Some specific FF item consumption segregated with environment (rural or urban) but with no overall significant relationship between the FF group and environment or gender.     

Total dietary intake of mercury in the Canary Islands, Spain.

Estimating the risk associated with dietary intake of heavy metals by consumers is a vital and integral part of regulatory processes. The assessment of exposure to mercury shown in this paper has been performed by means of a study on the whole diet. Total mercury (Hg) levels were determined by cold vapour atomic absorption spectrometry (AAS) in 420 samples of regularly consumed food and drink. The total Hg concentrations measured in the different groups of food ranged from non-detectable to 119 microg kg(-1) w/w. The fish group had the highest concentrations of total Hg. All groups of food with regulated Hg content showed levels that were lower than the legally set values. The food consumption data used in the analysis were taken from the latest nutritional survey made in the Canary Islands, Spain. The estimated total Hg intake of local population (5.7 microg/person day(-1)) did not exceed the provisional tolerable weekly intake (PTWI) limit of 0.3 mg week(-1) of total mercury (43 microg/person day(-1)) fixed by the Joint Food and Agricultural Organization/World Health Organization (FAO/WHO) Expert Committee on Food Additives. Fishery products contributed 96% of the total Hg intake. The mean Hg intake for each island in this archipelago, formed by seven, has also been calculated. Fuerteventura, Lanzarote and El Hierro are the islands with the highest level of Hg intake (7.0, 7,0 and 6.1 microg/person day(-1), respectively). La Palma Island, due to its low fish consumption, had the lowest level of Hg intake (4.5 microg/person day(-1)), followed by La Gomera (5.4 microg/person day(-1)), Tenerife (5.5 microg/person day(-1)) and Gran Canaria (5.6 microg/person day(-1)). A comparison has been made of the results obtained in this study with those found for other national and international communities.     

Content of free phenolic compounds in bananas from Tenerife (Canary Islands) and Ecuador

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 Pequeña 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<0.05) and lower than in bananas produced in Tenerife. Variations in the contents of these polyphenolic compounds in the bananas from Tenerife according to cultivation method (greenhouse and outdoors), farming style (conventional and organic) and region of production (north and south) were observed.     

Selenium and mercury concentrations in sweet and dry bottled wines from the Canary Islands, Spain.

The concentrations of selenium and mercury were determined by atomic absorption spectrophotometry in sweet and dry bottled wines from the Canary Islands, Spain. The concentrations of mercury ranged from 2.6 to 4.9 microg x l(-1) for sweet wines, and from 1.5 to 2.6 microg x l(-1) for dry wines, differences (p < 0.05) being observed according to the island of production and type of wine, but not with respect to vintage. The concentration of selenium varied between 1.0 and 2.0 microg x l(-1) for sweet wines, and between 0.6 and 1.6 microg x l(-1) for dry wines. Differences were found in the mean concentrations according to the type of wine. Dry wines produced in La Palma presented a higher (p < 0.05) mean content than those observed in the wines of El Hierro and Lanzarote.     

Modeling of coagulation,curd firming,and syneresis of goat milk from 6 breeds

Traditional milk coagulation properties are used to predict the suitability of milk for cheese-making. In bovine and ovine species, the introduction of the concept of curd firming over time, continuously recorded by a lactodynamograph during prolonged tests, provides additional information about milk coagulation, curd-firming, and syneresis processes. The aims of present study were (1) to test the adaptability of a 4-parameter curd-firming model in the assessment of goat milk (also comparing published data of other species); (2) to describe variability of coagulation, curd firming, and syneresis processes among individual goat milk samples; (3) to quantify the effects of farm and animal factors (breed, parity, and stage of lactation); and (4) to compare 6 goat breeds for their model parameters. Milk samples from 1,272 goats reared in 35 farms were collected. Goats were of 6 breeds: Saanen and Camosciata delle Alpi for the Alpine type; and Murciano-Granadina, Maltese, Sarda, and Sarda Primitiva for the Mediterranean type. During a lactodynamographic analysis (60 min), 240 measures of curd firmness (mm) were recorded for each milk sample. The modeling of curd firming allowed us to achieve the rennet coagulation time estimated on the basis of all the data points (min); the curd firming and the curd syneresis instant rate constants; the asymptotical potential value of curd firming; the actual maximum curd firmness; and the time at which the curd firming maximum level is attained. Modeling parameter data were analyzed using a linear mixed model. Comparison with other dairy species showed several differences: goat milk coagulated later than sheep but earlier than bovine, and curd firming and curd syneresis instant rate constants were greater in small ruminants. Modeling parameters of goat milk were mostly affected by the farm effect (37% of the total variance, on average) compared with the results found for bovine and ovine samples, and this was probably attributable to the marked differences among goat farming systems. Small differences were demonstrated between Alpine and Mediterranean breeds, but the time of maximum curd firmness was lower in Murciano-Granadina compared with Maltese, Sarda, and Sarda Primitiva. Sarda and Sarda Primitiva were very similar and exhibited the most favorable coagulation properties of milk. For almost all the model parameters, the direct effect of breed was increased after correction for milk yield and composition. In conclusion, this approach allowed us to fully depict the effects of the different factors on coagulation of goat milk, and clarified the different renneting pattern among goat breeds, and with other species. Results could be used for the valorization of goat dairy products, also when these are linked to particular local breeds, and to stimulate further studies about relationships between coagulation and cheese-making traits.     

Analysis of pesticide residues in bananas harvested in the Canary Islands (Spain)

In this work, 11 pesticides (ethoprofos, dimethoate, diazinon, malaoxon, chlorpyrifos-methyl, fenitrothion, malathion, chlorpyrifos, fenamiphos, buprofezin and phosmet) were analysed in 57 banana samples taken from the local markets of the Canary Islands (Spain). Analyses were carried out by the QuEChERS approach developed for pesticide residue analysis in food, using gas chromatography (GC) with nitrogen–phosphorus detection (NPD). Triphenylphosphate (TPP) was used as internal standard. Recoveries ranged between 67% and 118% with RSD values below 16%. Typical limits of quantification (LOQs) of the method were 0.01–0.14 mg/kg, which are below the EU maximum residue limits (MRLs) established for these compounds in bananas. Chlorpyrifos was detected in 50 samples (88%) in the concentration range 0.03–0.65 mg/kg, malathion in five samples (8.8%) in the concentration range 0.16–0.17 mg/kg, fenitrothion in four samples (7.0%) in the concentration range 0.02–0.10 mg/kg and buprofezin in one sample (1.8%) at 0.15 mg/kg. All these values are below the MRLs established for these compounds except for two samples containing fenitrothion. Among the studied pesticides only chlorpyrifos has a high occurrence in the samples. However, the levels of these residues cannot be considered a serious public health problem according to EU regulations. Because of the high occurrence of chlorpyrifos, its distribution between the pulp and the peel was also investigated. Results show that most of the pesticide remains in the peel and that only amounts between 0.07 and 0.12 mg/kg occur in the pulp even at concentrations in the peel as high as 0.87 mg/kg.     

Metallic content of wines from the Canary Islands (Spain). Application of artificial neural networks to the data analysis

Eleven elements, K, Na, Ca, Mg, Fe, Cu, Zn, Mn, Sr, Li and Rb, were determined in dry and sweet wines bearing the denominations of origin of El Hierro, La Palma and Lanzarote islands (Canary Islands, Spain). Analyses were performed by flame atomic absorption spectrophotometry, with the exceptions of Li and Rb for which flame atomic emission spectrophotometry was used. The content in copper and iron did not present risks of cases. All samples presented a copper and zinc content below the maximum amount recommended by the Office International de la Vigne et du Vin (OIV) for these elements. Significant differences in the metallic content were found among the different islands. Thus, Lanzarote presented the highest mean content in sodium and lithium and the lowest mean content in rubidium, and La Palma presented the highest mean content in strontium and rubidium. Sweet wines from La Palma, elaborated as naturally sweet with over-ripe grapes, presented mean contents significantly higher with regard to dry wines from the same island in the majority of the analysed elements. Cluster analysis and Kohonen self-organising maps showed differences in wines according to the island of origin and the ripening state of the grapes. Back-propagation artificial neural networks showed better prediction ability than stepwise linear discriminant analysis.