José F. Huidobro

Rapid determination of minority organic acids in honey by high-performance liquid chromatography

A rapid high-performance liquid chromatographic method for the determination of organic acids in honey is reported. Malic, maleic, citric, succinic and fumaric acids were identified and quantified in 15 min. First time repeatibility, reproducibility and recoveries were determined out for these acids in honey samples. Maleic acid was also quantified for first time by a chromatographic method. The organic acids were removed from honey by using a solid-phase extraction procedure with anion-exchange cartridges. Previously, the solution of honey was adjusted to pH 10.50 with 0.1 M NaOH and stirred for 15 min at room temperature. Then, this solution was adjusted to pH 5.00 with 0.1 M H2SO4. This procedure was carried out to avoid interferences in the baseline. The chromatographic separation was achieved with only one Spherisorb ODS-2 S5 column thermostated at 25 degrees C. Metaphosphoric acid (pH 2.20) was used as mobile phase at a flow-rate of 0.7 ml/min. Organic acids were detected with a UV-vis detector (215 nm). The precision results showed that the relative standard deviations of the repeatability and reproducibility were < or =3.20% and < or =4.86%, respectively. The recoveries of the organic acids ranged from 62.9 to 99.4%. Under optimum conditions the detection limits ranged from 0.0064 to 7.57 mg/kg and the quantification limits ranged from 0.025 to 10.93 mg/kg.

Evolution of fructose and glucose in honey over one year: influence of induced granulation

Abstract Evolution of fructose and glucose over 1 year has been evaluated in 30 honey samples from Burgos (N. Spain). The influence of the induced granulation process in this evolution was also determined. Each sample was divided into two aliquots of 500 g and aseptically bottled. One aliquot was directly stored and the second induced to crystallise by seeding with 10% of finely crystallised honey. Analyses of moisture content, pH, fructose and glucose were carried out over 1 year, once each 4 months. Both, fructose and glucose increased in most samples. Induced-crystallised samples did not show any significant differences in the evolution of the two sugars in comparsion with directly stored samples. Linear correlations were found, for both fructose and glucose, between samples directly stored and honeys in which granulation was induced. These results are clearly different from those reported in previous papers where decrease of monosaccharides below their original values was described. pH of honey might promote reversion of monosaccharides and the formation of disaccharides and trisaccharides. This investigation has demonstrated the possibility of formation of monosaccharides, by the hydrolysis of higher sugars, as a process predominant over the reversion. No statistical relationship was found between pH of honey samples and their fructose and glucose content evolution.

Significance of nonaromatic organic acids in honey.

Although organic acids represent < 0.5% of honeys constituents, they make important contributions to the organoleptic, physical, and chemical properties of honey. To date, approximately 30 nonaromatic organic acids have been identified in honey, but relatively little attention has been paid to these components. This article reviews the current literature related to the significance of nonaromatic organic acids in honey; it was written with a goal of attracting researchers to study these interesting honey components. Previous research contributions on nonaromatic organic acids in honey may be classified into five main areas: (i) the antibacterial activities of these acids, (ii) the antioxidant activities of these acids, (iii) the use of these acids as possible indicators of incipient fermentation, (iv) the use of these acids for treatment of Varroa infestation, and (v) the use of these acids as factors for the characterization of both botanical and geographical origins of honeys. We conclude that nonaromatic organic acids are of interest for diverse reasons and that there is a particular need for studies regarding their possible antibacterial and antioxidant activities.

Diastase, invertase and beta-glucosidase activities in fresh honey from north-west Spain

SUMMARYDiastase (α- and β-amylase), invertase (sucrase or α-glucosidase) and β-glucosidase activities in 46 samples of unheated, commercially purchased Galician (north-west Spain) honeys were determined spectrophotometrically. The honeys were from Eucalyptus sp. (25), Rubus sp. (2) and Castanea sativa (1), or multifloral in origin (18). The mean value for diastase (Gothe scale) was 19.3 ± 6.99 (10.6–38.0), for invertase it was 128.3 ± 31.90 (68.7–225.4) μmoles p-nitrophenyl glycoside hydrolysed/kg honey/min, and for β-glucosidase it was 110.8 ± 19.89 (80.3–176.4) μmoles p-nitrophenyl glycoside hydrolysed/kg honey/min. Correlationships were found between invertase and diastase activities (r = 0.878) and between invertase and β-glucosidase activities (r = 0.871). Comparisons between these values and those obtained by other authors are discussed.

Analytical Methods for the Determination of Organic Acids in Honey

Although organic acids represent less than 0.5% of honeys constituents, they make important contributions to organoleptic, physical, and chemical properties of honey. They could be used as fermentation indicators, for the treatment of Varroa infestation, and to discriminate among honeys according to their botanical and/or geographical origins. This article reviews the current literature related to the analytical methods (enzymatic, chromatographic and electrophoretic) that have been applied recently to the determination of honeys organic acids. The advantages and disadvantages of all the procedures described are also discussed. This review has been written to make the study of these interesting honey component easier.

Solid-phase extraction procedure to remove organic acids from honey.

A solid-phase extraction procedure was applied to remove organic acids from honey. Malic, maleic, citric, succinic and fumaric acids were isolated with an anion-exchange cartridge. The different parameters which affected the extraction procedure were studied and optimised to establish the optimal conditions for maximum recovery of organic acids and minimum extraction of interferences. The optimised procedure used a cartridge which was activated with 10 ml of 0.1 M sodium hydroxide solution (percolation rate 3 ml/min). A 10 ml volume of honey solution was passed at a flow-rate of 0.5 ml/min. The cartridge was washed with 10 ml of water (3 ml/min) and organic acids were eluted with 4 ml of 0.1 M sulfuric acid (0.5 ml/min). This solution was injected directly into the chromatograph. When this procedure was carried out on standard solutions of organic acids, recoveries between 99.2 and 103.4% were found. If this procedure was applied to honey samples these recoveries were also satisfactory and ranged from 62.9 to 99.4%.

Acaricide residues in honeys from Galicia (N.W. Spain)

Honey samples (101) from Galicia (N.W. Spain) were analyzed by gas chromatography (electron capture and flame ionization) for the presence of acaricides (amitraz, bromopropylate, coumaphos, and fluvalinate). Seventy-three samples were free from detectable residues. Bromopropylate residues were found in 16 samples in levels ranging from 5 to 60 microg/kg. Fluvalinate residues were found in 11 samples in levels ranging from 10 to 40 microg/kg. One sample contained 100 microg of fluvalinate per kg. Neither amitraz nor coumaphos residues were detected.

Acaricide Residues in Honey: Analytical Methods and Levels Found

A bibliographic review on the pollution of honey with acaricides is presented. This paper reviews methods for determining amitraz, bromopropylate, coumaphos, cymiazole, fluvalinate, malathion and phenothiazine residues in honey samples, as well as multiresidue methods. Acaricide residue levels found in European countries are also reviewed.

Rapid capillary zone electrophoresis method for the determination of metal cations in beverages.

A rapid and reliable capillary zone electrophoresis method for the determination of inorganic cations was developed. The complete separation of K(+), Ba(2+), Ca(2+), Na(+), Mg(2+), Mn(2+), Ni(2+), Cd(2+), Li(+) and Cu(2+) can be achieved in 4min with a simple electrolyte composed by 10mM imidazole as the carrier buffer and background absorbance provider and acetic acid as the complexing agent (pH 3.60). Injection was performed hydrostatically by elevating the sample at 10cm for 30s. The running voltage was +25kV at room temperature. Indirect UV-absorption detection was achieved at 185nm. The detection limit was in the range between 0.06mg/l (Mg(2+)) and 0.57mg/l (K(+)) and the quantification limits ranged from 0.10mg/l (Ni(2+)) to 0.80mg/l (Cu(2+)). The calibration graphs were linear in the concentration range from the quantification limit till at least 1g/l in K(+), 10mg/l in Ba(2+), Ca(2+), Mg(2+), Mn(2+), Ni(2+) and Cd(2+), 40mg/l in Na(+) and 12mg/l in Li(+) and Cu(2+). The repeatability, intraday and interday analysis were </=1.55% and </=3.64% for migration time and </=3.38% and </=3.63% for peak area. The method developed has been applied to several beverage samples with only a simple dilution and filtration treatment of the sample. The proposed method is simple, fast, cheap and it is achieved with common products in either laboratory. For these reasons, it is a very useful method for routine analysis.

Nonacaricide pesticide residues in honey : analytical methods and levels found

A bibliographic review on honey pollution with pesticides is presented. This paper reviews the methods set up for determining pesticide residues in honey samples as well as the pesticide residue levels found in European countries.