J. Simal-Lozano

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.

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.

Protein, amino acid and fatty acid contents in raw and canned sea urchin (Paracentrotus lividus) harvested in Galicia (NW Spain)

Moisture, protein, amino acid and fatty acid contents of raw and canned sea urchin (Paracentrotus lividus) gonads were determined. Sea urchin showed a high moisture content (73%) and a high level of proteins (56% dry matter). The canning process, evaluated at 112 °C for 50 min, did not lead to significant changes in protein, amino acid and fatty acid contents relative to the raw sample. © 2000 Society of Chemical Industry

Monitoring of the vitamin C content of frozen green beans and Padrón peppers by HPLC

Abstract: HPLC (using a C18 column, water at pH 2E2 as mobile phase, and UVdetection) was used to monitor the vitamin C content of deep-frozen ([22iC)green beans and Padro“ n peppers over 12 months. Unblanched beans andpeppers lost P97% of their vitamin C within 1 month of freezing, whether or notthey were contained in bags sealed under vacuum. Blanching reduced the beansIvitamin C content by 28%, but limited further decreases to between 3 (vacuumsealed) and 10% (no vacuum) in 12 months. These results conÐrm the utility ofblanching in the preservation of vegetables by deep-freezing. 1998 SCI.(J Sci Food Agric 76, 477E480 (1998)Key words: deep-freezing; HPLC; ascorbic acid; green beans; peppers INTRODUCTIONHumans are among the few mammals incapable of bio-synthesis of ascorbic acid, or vitamin C. The amount ofthis vitamin in foodstu†s should therefore be carefullymonitored with a view to avoiding deÐciency, which inextreme cases causes scurvy and, moreover, leads toreduced resistance to infection (Anderson et al 1987).Vitamin C is almost exclusively found in fruit andvegetables although the amount present varies amongvarieties (Morrison 1975) according to factors such asthe stage of development and size of the produce(Selman and Rolfe 1982), and the time between harvest-ing and processing (Kozar et al 1988). This variation isreNected in the diversity of vitamin C content reportedin the literature for fresh produce.The seasonality and high perishability of fruit andvegetables provides opportunity to apply preservation

Composition of babaco, feijoa, passionfruit and tamarillo produced in Galicia (North-west Spain)

Basic compositional data are evaluated for the subtropical fruits (babaco, feijoa, passionfruit, and tamarillo) growing in Galicia (North-west Spain)

The effects of various culinary treatments on the pigment content of green beans (Phaseolus vulgaris, L.)

The effects of four culinary treatments (steaming and boiling in a covered pot, a pressure cooker or a microwave oven) on the chlorophyll a and b, all-trans-lutein, phaeophytin a and b and all-trans-β-carotene (provitamin A) contents of green beans (Phaseolus vulgaris, L.) were evaluated. The pigments in the fresh and treated beans were determined by gradient elution reverse-phase HPLC with UV detection. Boiling the beans in a covered pot, pressure cooking or microwaving them caused smaller losses of pigments than steamed cooking. Since pressure cooking also generally leads to smaller losses of nutritious components (e.g. vitamin C), it is recommended over the traditional method of boiling beans in a covered pot.

Chemical composition of Padrón peppers (Capsicum annuum L.) grown in Galicia (N.W. Spain)

The water, neutral-detergent fibre, D-glucose, D-fructose, sucrose, vitamin C, organic acid, starch, pectin and major pigment contents of Capsicum annuum L. var. Longum grown in Galicia (N.W. Spain) are determined. After water, insoluble fibre was the most abundant component of these peppers (NDF 2.2 g/100 g of fresh fruit). Their vitamin C content was rather low (24 mg/100 g).

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%.

Evaluation of the performance of a multiresidue gas chromatographic method for the determination of aliphatic hydrocarbons in mussels of Galicia (N.W. Spain)

Abstract The determination of aliphatic hydrocarbons in blue mussel ( Mytilus galloprovincialis ) was performed using a multiple component extraction method and temperature-programmed capillary GC using splitless injection mode and flame ionization detection. Calculated recoveries for the overall procedure to give concentrations of the different aliphatic hydrocarbons in the low level end ( ca 10 μg/ml) of the calibration range (2–200 μg/ml) ranged from 70 to 92% [coefficients of variation (CVs) 9–20%]. Limits of detection for the overall procedure were between 40 and 60 ng/g of sample (extraction concentration factor 25 g/ml) and GC-FID determination precision was good (CVs 1–4%). Aliphatic hydrocarbon levels in mussels in Galicia were similar to those found in areas generally considered unpolluted.