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.     

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.     

Subcritical water extraction of phenolic compounds from potato peel

Potato peel, a waste generated from potato processing, is a disposal problem. But, potato peel is a good source of functional ingredients such as phenolic compounds. This study investigated the extraction of eight phenolic compounds (Gallic acid, GAC; Chlorogenic acid, CGA; Caffeic acid, CFA; Protocatechuic acid, PCA; Syringic acid, SGA; p-hydroxyl benzoic acid, PBA; Ferulic acid, FRA and Coumaric acid, CMA) from potato peel using subcritical water.Experiments were performed in a batch stainless steel reactor at 6 MPa, 2 mL/min and temperatures ranging from 100 to 240 °C at residence time of 30 to 120 min. High recoveries of phenolic compounds (81.83 mg/100 g; wet basis wb) were obtained at 180 °C and extraction time of 30 min compared to 3 h extraction with methanol (46.59 mg/100 g wb). CGA (14.59 mg/100 g wb) and GAC (29.56 mg/100 g wb) were the main phenolic compounds obtained from potato peel at 180 °C. Subcritical water at 160 to 180 °C, 6 MPa and 60 min might be a good substitute to organic solvents such as methanol and ethanol to obtain phenolic compounds from potato peel.     

Mineral and trace element concentrations of dairy products from goats’ milk produced in Tenerife (Canary Islands)

The concentrations of the minerals, Na, K, Ca and Mg, and the trace elements, Fe, Cu, Zn and Se, were determined in 400 samples of goats’ dairy products (100 raw milk, 100 whey, 100 fresh and 100 semi-hard cheeses) produced in the island of Tenerife. All the minerals and trace elements analysed presented significant differences in the concentration between the dairy products analysed. The season of production had a greater influence on the mineral and trace element concentration than the region of production and the amount of fibre in the goats’ diet. An almost complete differentiation of the samples according to the type of dairy product was observed applying a stepwise discriminant analysis.     

Quality evaluation of broom honey (Spartocytisus supranubius L) produced in Tenerife (The Canary Islands)

The qualities of 24 samples of broom (Spartocytisus supranubius L) honey from Mount Teide National Park (Tenerife) were evaluated. A total of 33 pollen types was identified. The study demonstrated the predominance of Spartocytisus supranubius, and minor incidence of Echium wildpretii, Descurainia bourgaeana, Erysimum scoparium and Pteocephalus lasiospermus, which are major edemic plants of this zone. The low electrical conductivity was typical of pale honeys. Most samples showed a proper maturity indicated by the low water content. Since the hydroxymethylfurfural content was also low, good freshness was indicated. The free acidity (below 16.8 meq kg^?1) indicated the absence of undesirable fermentation, and the mean pH (around 3.89) is usual for this kind of honey. The fructose/glucose ratio was 1.29 ± 0.07 and sucrose content averaged 9.9 ± 9.3 g kg^?1, with significance presence of erlose (24.4 ± 16.8 g kg^?1). Among the 12 organic acids detected, gluconic, isobutyric and butyric acids were identified in the majority of samples at high concentrations. Malic acid which was also present can be used as an marker for the differentiation of broom honey. Copyright © 2004 Society of Chemical Industry     

Content of toxic and essential metals in canned mussels commonly consumed in Tenerife, Canary Islands, Spain

Concentrations of three toxic heavy metals (Hg, Pb, Cd) and six essential heavy metals (Fe, Zn, Mn, Cr, Cu, Ni) were determined in mussel conserves (Mytilus galloprovincialis, Bivalvia, Mollusca) consumed habitually by individuals in Tenerife (Canary Islands, Spain). A total of 600 samples were analyzed, corresponding to six different commercial brands and four different processing types: pickled sauce (mixture of olive oil, vinegar, red pepper, laurel, and salt), coquille St. Jacques sauce (coquille St. Jacques broth), nature (water and salt), and bionature (water, salt, and soluble vegetal fiber). Samples were collected weekly from markets in Santa Cruz de Tenerife during a 12-month period. All values for toxic metals were lower than the permitted maximum for human consumption as proscribed in European Community Directive 2001/22/CE (1,000 microg/kg wet weight for Pb and Cd) and European Community Decision 93/351/EEC (500 microg/kg wet weight for Hg). For the six essential heavy metals, mussels are a very good source, contributing high percentages of the recommended daily allowance.     

Analysis of organic acid content in cultivars of tomato harvested in Tenerife

The determination of organic acids in tomato samples was optimized using the HPLC method with on-line photodiode array detection, previous to extraction with 80% ethanol at room temperature and clean-up in Accell Plus QMA cartridge. The organic acids (oxalic, pyruvic, malic, citric, fumaric and ascorbic), Brix degree, acidity and pH were determined in five tomato cultivars (Dorothy, Boludo, Dominique, Thomas and Dunkan) harvested in Tenerife. There are several significant differences among cultivars in the concentration of many acids. The cultivation method, sampling period and the region of production were also considered. Citric, malic and oxalic acids were the major organic acids in all the cultivars. Some significant differences in the studied parameters were observed between the cultivars. The cultivation method and sampling period influenced in a variable way the studied parameters, depending on the tomato cultivar. The production region influenced the ascorbic acid concentration of the tomatoes. Applying stepwise discriminant analysis, it was found that the sampling period is more important in the differentiation of the tomato samples than the cultivar, cultivation method and production region.     

高效液相色谱法测定菱角中的没食子酸含量

目的:用高效液相色谱法测定菱角药材中没食子酸的含量。方法:采用C18(4.6mm×200mm)色谱柱,甲醇—0.5%乙酸水溶液(15:85)为流动相,流速1ml/min,柱温27℃,在271nm下进行检测。结果:菱角中没食子酸含量为0.08%,平均回收率为98.3%,RSD为1.89%。结论:采用高效液相色谱法测定菱角中没食子酸的含量,简便、快速、准确。为进一步制定菱角药材的质量标准提供了依据。     

Retardation of myoglobin and haemoglobin-mediated lipid oxidation in washed bighead carp by phenolic compounds

Antioxidative activities of phenolic compounds (caffeic acid, gallic acid and tannic acid; 200 ppm) in washed mince (pH 6), with added myoglobin (Mb) and haemoglobin (Hb), from bighead carp (Hypophthalmichthys nobilis), during 9 days of iced storage, were studied. Tannic acid exhibited the preventive effect on discolouration of washed mince containing Mb or Hb during storage (P < 0.05). High peroxide value (PV) was found and large amount of, thiobarbituric acid-reactive substances (TBARS) and hexanal were formed in washed mince containing haem proteins, especially Hb. As determined by apo Streptococcal haem-associated protein, Hb had the lower haem affinity than Mb. Phenolic compounds, especially caffeic acid and gallic acid, could lower lipid oxidation induced by Mb or Hb throughout storage (P < 0.05). Prevention of haem release, as well as inhibition of lipid oxidation induced by haem proteins with selected phenolic compounds, should be an alternative means in lowering discolouration and lipid oxidation in fish muscle.     

Total phenolic compounds and antioxidant capacities of major fruits from Ecuador

Seventeen fruits from Ecuador were analysed for total soluble phenolic compounds content and for antioxidant capacity, using three different methods (DPPH, FRAP and ABTS⁺). For the total phenolic content measured by the Folin–Ciocalteu method, three groups, having <100, 200–500 and >1000 mg GAE/100 g FW, were clearly distinguishable. Andean blackberry, capulí cherry peel and banana passion fruit were classified in the third group, with concentrations of 2167, 1494 and 1010 mg of GAE/100 g FW, respectively. Antioxidant capacity analyses revealed the same classes. FRAP and ABTS⁺ gave comparable results and were highly correlated (y = 0.691x + 6.78; r² = 0.908). Spectrophotometric measurements showed that the Andean blackberry and capulí peel but not banana passion fruit contained high levels of anthocyanins (λ_max = 520 nm).     

Quantification of gallic acid and ellagic acid from longan (Dimocarpus longan Lour.) seed and mango (Mangifera indica L.) kernel and their effects on antioxidant activity

Gallic acid (GA) and ellagic acid (EA) have been identified in longan seed and mango kernel by the use of reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with photodiode array detection (DAD). The ethanolic extract of longan seed contained 23.3 and 156 mg/100 seeds of GA and EA, respectively. The ethanolic extracts of mango kernel contained approximately 87% more GA than the longan seed ethanolic extracts but about 32% less EA. After heat treatment and acid hydrolysis, mango kernel had higher concentrations of GA and EA, contributing to more potent antioxidant activity. The results demonstrated rich sources of GA and EA in longan seed and mango kernel which might provide a novel source of these natural antioxidants.     

Influence of thermal treatment on phenolic compounds and antioxidant properties of oak acorns from Serbia

The aim of the present work was to investigate and compare phenolic compounds and antioxidant activity of methanol extracts of Quercus robur and Quercus cerris acorn kernels obtained before and after thermal treatment. Content of total phenolics, tannins, non-tannin phenolics and flavonoids was determined spectrophotometrically and content of gallic acid with HPLC. Antioxidant activity of the samples was assayed through FRAP (Ferric Reducing Antioxidant Power), DPPH scavenging test and inhibition of Fe²⁺/ascorbate induced lipid peroxidation. Extracts of native and thermally treated kernels showed high antioxidant activity, with extracts of thermally treated kernels being more active than extracts of native ones. Hydrolysable tannins and gallic acid were identified in all samples. Non-tannin phenolics, including gallic acid, were present in significantly higher quantities in thermally treated samples, whilst tannin content decreased. This indicates that during thermal treatment hydrolysable tannins were degraded. As the result of this degradation and consequent increase of non-tannin phenolics content, and amongst them especially gallic acid, thermally treated samples possess higher antioxidant activity than do the native ones. The obtained results have provided further grounds for establishing Q. robur and Q. cerris acorn kernels as a source for functional food preparation.     

Phytic acid level in edible grain derivatives in the Canary Islands (gofio and frangollo)

Laccaria and Hygrophorus species, Craterellus cornucopioides, Gomphidius glutinosus, Macrolepiota rhacodes and Hydnum repandum. The inhibiting activities found were higher than those of cereals but lower than those of some fabaceous plants. Received: 29 November 1999 / Revised version: 14 February 2000     

Determination of phenolic compounds in aromatic plants by RP-HPLC and GC-MS

It is well known that phenolic compounds are constituents of many plants and herbs, and they have attracted a great deal of public and scientific interest because of their health-promoting effects as antioxidants. Five plants, Vitex agnus-castus (Verbenaceae), Origanum dictamnus (Lamiaceae), Teucrium polium (Lamiaceae), Lavandula vera (Lamiaceae) and Lippia triphylla (Verbenaceae), were examined in order to determine their phenolic composition. Reversed phase high performance liquid chromatography was employed for the identification and quantification of phenolic compounds. Gas chromatography–mass spectometry(GC-MS) was also used for identification of phenolic compounds after silylation. Analysis of the non-volatile and thermolabile phenolic compounds by GC-MS presupposes their conversion into volatile and thermotolerant derivatives. The derivatization process was optimized against reagents, temperature and reaction time. A large excess of N,O-bis(trimethylsilyl)trifluoroacetamide containing trimethylchlorosilane proved to be the best derivatization reagent to convert analytes into volatile trimethylsilyl derivatives. The most abundant phenolic compounds detected were caffeic acid (0.12–0.93 mg 100 g⁻¹ dry sample), ferulic acid (0.34–1.52 mg 100 g⁻¹ dry sample), and (+)-catechin (0.22–0.43 mg 100 g⁻¹ dry sample).     

Determination of some individual phenolic compounds and antioxidant capacity of mead produced from different types of honey

The aim of this study was to promote mead (honey wine) production by testing the appropriateness of different honey varieties which were obtained from the flora of Turkey for the production of mead. Cotton‐Mezda (Gossypium spp.), pine (Pinus spp.) and flower honeys were used in the fermentation studies. Pure culture Saccharomyces cerevisiae yeasts were used in the mead studies. While determining the phenolic contents of meads via HPLC method, five phenolic acids and two flavonoids were used as standards with known antioxidant properties. In addition, total antioxidant activity was analysed in meads using trolox equivalent antioxidant capacity (TEAC). Among the phenolic acids, the most abundant one was protocatechuic acid (75.12–179.03 μg/L) and among flavonoids it was catechin (10.38–125.55 μg/L). It was found out that total phenolic content ranged from 103.56 GAE to 167.89 GAE mg/L. Copyright © 2017 The Institute of Brewing & Distilling     

Analysis of phenolic compounds and isoflavones in soybean seeds (Glycine max (L.) Merill) and sprouts grown under different conditions

Soybeans (Glycine max (L.) Merill) are popularly known as a healthy food in many Asian countries and are mostly consumed as soymilk, tofu, and fermented products such as miso, temph, and sufu. The objective of this study was to determine the variation and composition of phenolic compounds and isoflavone contents in soybean seeds [Glycine max (L.) Merill] and sprouts [Kongnamul] grown under dark conditions (producing yellow soybean sprouts) and in green and yellow boxes (producing green soybean sprouts). In seven soybean cultivars, the total phenolic content ranged from 6.67 μg⁻¹ in Pureunkong to 72.33 μg⁻¹ in Poongsannamulkong. The average total phenolic content in the green soybean sprouts (48.33 μg⁻¹) was higher than in the yellow soybean sprouts (29.75 μg⁻¹). The total phenolic content in the yellow soybean sprouts varied from 9.88 μg⁻¹ to 47.71 μg⁻¹, and the total phenolic content in the green soybean sprouts varied from 29.21 μg⁻¹ to 79.70 μg⁻¹. Only four phenolic compounds, p-hydroxybenzoic acid, salicylic acid, p-coumaric acid, and ferulic acid, were detected in all soybean cultivars. Syringic acid was not detected in yellow soybean sprouts, and myricetin was only detected in yellow soybean sprouts (4.65 μg⁻¹) from the Pureunkong cultivar grown under dark conditions. The total isoflavone content in soybean seeds ranged from 2.1 μg⁻¹ in Sowonkong to 33.0 μg⁻¹ in Pureunkong, and the mean total isoflavones was 10.61 μg⁻¹. Green soybean sprouts had higher average total isoflavones (1389.4 μg⁻¹) than yellow soybean sprouts (559.2 μg⁻¹), and the total isoflavone content was highest in the Pureunkong yellow soybean sprouts (756.3 μg⁻¹) and the Sowonkong green soybean sprouts (2791.6 μg⁻¹). In soybean sprouts, the higher the (malonyl)-daidzin or (malonyl)-genistein content, the higher the total isoflavone level. Our study suggests that producing soybean sprouts enriched in isoflavones under coloured-light sources is feasible.     

Enzyme-assisted extraction of phenolic compounds and proteins from sugarcane bagasse using a low-cost cocktail from Auricularia fuscosuccinea

Sugarcane bagasse is the major by-product of the sugarcane industry, and it can serve as a substrate for biotechnological processes for obtaining value-added products. This study gave multiple adding values to sugarcane bagasse using it in two separate bioprocesses. Sugarcane bagasse was used as a substrate for enzymatic cocktail production from Auricularia fuscosuccinea LBM 244 and as a source of proteins and phenolic compounds. A. fuscosuccinea LBM 244 enzyme cocktail-assisted extraction, commercial enzyme assisted extraction and conventional extraction were compared. Enzymatic-assisted extractions released 557–827% more protein content than those at 0 h. A. fuscosuccinea LBM 244 enzyme cocktail released 50% and 30% phenolic compounds more than conventional and commercial enzyme extraction, respectively. These phenolic compounds were represented mainly by ρ-coumaric and ferulic acids. On top of that, the cost of the enzymes in enzyme-assisted extraction was reduced fourfold using the A. fuscosuccinea LBM 244 enzyme cocktail.     

Content of antinutritional factors and HCl-extractability of minerals from white bean (Phaseolus vulgaris) cultivars: Influence of soaking and/or cooking

White bean seeds were subjected to soaking in distilled water for 1, 2 and 3 days. In order to perform complete processing, the seeds were cooked until soft. Effects of soaking and/or cooking of white bean seeds on antinutritional factors, mineral contents and HCl-extractability were studied. Phytic acid and polyphenol contents of all cultivars were reduced. Soaking alone and soaking, followed by cooking, reduced mineral contents of the cultivars, but HCl-extractability was significantly (P ? 0.01) improved to varying extents, depending on cultivar type. Soaking and/or cooking treatment was thus found to be an effective technique and caused further improvement in the availability of both major and trace minerals in white bean.