Bioactive properties of honey with propolis

Nowadays, propolis is used as an innovative preservative and as a bioactive food supplement. Due to its bitter and astringent flavour, propolis is hardly accepted by consumers. The aim of this study was to obtain a likeable food product made with honey and propolis, whose antimicrobial, antioxidant and anti-inflammatory properties were enhanced in comparison with those of the base honeys used. 0.1%, 0.3% and 0.5% soft propolis extracts were added to honeys and the products that most appealed to the users were subjected to further research. Total phenolics, flavonoids, ABTS free radical and hydroxyl radicals scavenging and anti-inflammatory activities increased in all mixtures. Antimicrobial activity of the combined products showed synergic effects, resulting in higher results than those of the base honeys and propolis extracts. Therefore, honeys enriched with small amounts of propolis extracts are promising functional foods.

Determination of vitamin B(6) in cooked sausages

A reverse-phase high-performance liquid chromatography (HPLC) method has been described for the determination of various active forms of vitamin B(6) in meat products. Different extracting agents were tested to solubilize fully the analyte for quantification. The best data were obtained by extracting the samples with 5% (w/v) metaphosphoric acid. Separation by HPLC was performed with fluorescence detection (excitation, 290 nm; emission, 395 nm), on a 10 cm x 0.46 cm i.d. Hypersil BDS C(18) 5 microm column using a mixture of 50 mM phosphate buffer (pH 3.2) and acetonitrile (99:1, v/v) as mobile phase. Precision of the method was 0.5% (within a day) and 4.3% (between days). The detection limits were 0.020 mg/100 g for pyridoxal and pyridoxamine, 0.017 mg/100 g for pyridoxamine phosphate, 0.500 mg/100 g for pyridoxal phosphate, and 0.033 mg/100 g for pyridoxol, with a signal-to-noise ratio of 3. The recovery ranged from 92.0 to 100.0%.

Simultaneous determination of nicotinic acid and nicotinamide in cooked sausages

A simple and sensitive method for determining simultaneously nicotinic acid and nicotinamide content in cooked sausages by ion-pair reversed-phase liquid chromatography is described. Samples are extracted with ultrapure water, centrifuged, deproteinized with zinc hydroxide, filtered, and chromatographed with UV detection at 261 nm on a 25 cm x 4 mm i.d. Spherisorb ODS-2 cartridge using as mobile phase a mixture consisting of 5 mM heptanesulfonic acid adjusted to pH 3.3 with phosphoric acid and acetonitrile (75:25, v/v). Both vitamins are measured on a reversed-phase column with a single ion-pair reagent. Precision of the method was 0.5 and 1.0% (within a day) and 2.3 and 4.5% (between days) for nicotinic acid and nicotinamide, respectively. The detection limit was 0.300 mg/100 g. The recovery was >92% of nicotinic acid and nicotinamide added to samples of meats. Twenty samples of six different products have been analyzed in duplicate. The mean value for nicotinic acid ranged between 0.908 and 1.267 mg/100 g of fresh weight and for nicotinamide between 1.968 and 2.880 mg/100 g of fresh weight.

Determination of total riboflavin in cooked sausages

A simple and rapid method for determining riboflavin content in cooked sausages by ion-pair reversed-phase liquid chromatography has been set up. Samples were subjected to acid and enzymatic hydrolysis. Sample extracts were directly chromatographed, avoiding purification and concentration treatment. Final determination was performed by high-performance liquid chromatography with fluorescence detector (excitation, 227 nm; emission, 520 nm), on a 25 cm x 4 mm i.d. Spherisorb ODS-2 cartridge using a mixture of 5 mM heptanesulfonic acid adjusted to pH 2.7 with phosphoric acid and acetonitrile (75:25, v/v) as mobile phase. Precision of the method was 1.3% (within a day) and 2.6% (between days). The detection limit was 0.015 mg/100 g. The recovery was >95%.

Determination of thiamin in cooked sausages

A reliable and rapid high-performance liquid chromatography (HPLC) method has been set up for the determination of total thiamin in difficult sample matrices such as cooked sausages. Different hydrolysis conditions and enzymes were tested to release the vitamin from its phosphate ester. The best data in the enzymatic digestion were obtained by incubating the samples with 6% clara-diastase at 50 degrees C for 3 h. After oxidation of thiamin to thiochrome, the sample extracts were purified by using a C(18) Sep-Pak cartridge. Final determination was performed by reversed-phase HPLC with fluorescence detector (excitation 360 nm, emission 430 nm), on a low-cost 25 cm x 4 mm i.d. Spherisorb C(8) cartridge using a mixture of 5 mM phosphate buffer pH 7.0 and acetonitrile (70:30, v/v) as mobile phase. Precision of the method was 1.5% (within a day) and 5. 2% (between days). The detection limit was 0.015 mg/100 g. All the recoveries from the different cooked sausages were better than 90% of thiamin hydrochloride added to samples of meats. In the samples analyzed, the mean value for thiamin was between 0.039 and 0.508 mg/100 g fresh weight.

Enzymatic Determination of Citric Acid in Honey by Using Polyvinylpolypyrrolidone Clarification

To characterize honey types, a citric acid determination may be useful. A citric acid determination on honey was carried out with previous polyvinylpolypyrrolidone (PVPP) clarification followed by the Boehringer-Mannheim GmbH enzymatic test. The sample solution was prepared from 2 g of honey in 100 mL of Milli-Q water. A volume of 10 mL of this sample was clarified with PVPP stirring for 1 min and filtered. The enzymatic determination was measured spectrophotometrically at 340 nm, using citrate lyase, L-malate dehydrogenase, and L-lactate dehydrogenase. With these conditions, there were no observed interference effects. The proposed method improves precision [coefficient of variation (CV) between 0.26% and 1.60%] and recovery (between 98.0% and 100.9%) on the direct enzymatic analysis (% CV between 1.02 and 2.66 and recovery between 84.0% and 115.6%). Furthermore, the cost was reduced 70% using a microtest. The method was applied to 20 honeys of Galicia (northwestern Spain), and the results ranged between 44.2 and 827.0 mg of citric acid/kg of honey (mean = 192.9 mg/kg).

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.