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We have developed an in situ methodology for determining nitrite concentration in processed meats that can also be used by unskilled personnel. It is based on a colorimetric film-shaped sensory polymer that changes its color upon contacting the meat and a mobile app that automatically calculates the manufacturing and residual nitrite concentration by only taking digital photographs of sensory films and analyzing digital color parameters. The film-shaped polymer sensor detects nitrite anions by an azo-coupling reaction, since they activate this reaction between two of the four monomers that the copolymer is based on. The sensory polymer is complemented with an app, which analyzes the color in two different digital color spaces (RGB and HSV) and performs a set of 32 data fittings representing the concentration of nitrite versus eight different variables, finally providing the nitrite concentration of the test samples using the best fitting curve. The calculated concentration of nitrite correlates with a validated method (ISO 2918: 1975) usually used to determine nitrite, and no statistically significant difference between these methods and our proposed one has been found in our study (26 meat samples, 8 prepared, and 18 commercial). Our method represents a great advance in terms of analysis time, simplicity, and orientation to use by average citizens., The authors gratefully acknowledge the financial support provided by all funders. S.V. received funding from “La Caixa” Foundation (Grant LCF/PR/PR18/51130007). J.M.G. received funding from “Spanish Agencia Estatal de Investigación” (Grant PID2020-113264RB-I00/AEI/10.13039/501100011033). The authors also appreciate the support and collaboration of the company Inforapps for the development of the smartphone application “Colorimetric Titration”.

Glucose oxidase (GOX) and catalase (CAT) regulate the amount of H2O2 in honey, by generating or consuming it, so they are related to the antibacterial and antioxidant activity of honey. However, their activities are hardly analysed, since the process requires a previous dialysis that is non-selective, very time-consuming (>24 h), eco-unfriendly (>6L of buffer) and expensive. This research shows the design and performance of a material that selectively removes the actual interferents. The film-shaped-polymer is immersed for 90́ within a honey solution (12.5 mL of buffer), where it interacts exclusively with 1,2-dihydroxybenzenes, which we proved to be the real interferents (the material contains motifs derived from phenylboronic acid to interact with 1,2-diols). Polymeric chains favour condensation to occur exclusively with 1,2-dihydroxybenzenes, excluding monosaccharides. The interferents’ removal using our designed polymer is selective, low cost (1.42€ per test), rapid and eco-friendly (saves 6L of buffer and 20.5 h of experimental workout per sample)., We gratefully acknowledge the financial support provided by all funders. Author Jose Miguel García received grant PID2020-113264RB-I00 / AEI / 10.13039/501100011033 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”. Ana Arnaiz received funding from Ministerio de Universidades-European Union in the frame of NextGenerationEU RD 289/2021 (Universidad Politécnica de Madrid). We also gratefully acknowledge European Regional Development Fund (ERDF). Gianluca Utzeri thanks Fundação para a Ciência e a Tecnologia (FCT, Portugal) for PhD grant (SFR/BD/146358/2019). The Coimbra Chemistry Centre is supported by the FCT, through Projects UIDB/00313/2020 and UIDP/00313/2020. To all the beekeepers who provided a sample of honey for this study.

This study was aimed to assess quality, authentication parameters and trolox equivalent antioxidant capacity (TEAC) of Algerian and imported honeys sold in Algerian markets. Results indicated that 80% Algerian samples fulfilled international standards, whereas only 21.4% imported honeys were in agreement with the current regulations. 13.3% Algerian samples and 7.1% imported honeys showed values of proline lower than 180 mg/kg, which is the recommended limit for authentic honeys. Comparing Algerian and imported honeys, electrical conductivity, degrees Brix, diastase activities and proline contents were higher in Algerian honeys, in contrast to moisture percentages, hydroxymethylfurfural contents and acid phospatase activities that were higher in imported honeys. Methanolic extracts of Algerian samples were richer both in total phenolics and flavonoids determined in alkaline medium. There were not significant differences between Algerian and imported samples concerning pH, free acid, invertase, total carotenoid, total phenolics of raw honeys and TEAC, as well as regarding total flavonoids determined in neutral medium and o-diphenols of honeys’ methanolic extracts. Principal components analysis showed a good separation between Algerian and imported samples, only one multifloral Algerian honey being misclassified. Our research showed that a legal frame for Algerian honeys is of utmost importance. Spurge-labeled honeys were grouped, showing interesting common features that should be taken into account in a future regulation, in which a protected designation of origin for spurge honeys could be considered.

Honey is an important food for man and has been used as a natural sweetener since ancient times. It is a viscous and aromatic product made by honey bees using the nectar of flowers or honeydew. Hon...

We report on an innovative method to measure the Zn(II) concentration in commercial pet food samples, both wet and dry food. It is based on a colorimetric sensory polymer prepared from commercial monomers and 0.5 % of a synthetic monomer having a quinoline sensory core (N-(8-(2-azidoacetamido)quinolin-5-yl)methacrylamide). We obtained the sensory polymer as crosslinked films by thermally initiated bulk radical polymerization of the monomers of 100 μm thickness, which we punched into Ø6 mm sensory discs. The immersion of the discs in water solutions containing Zn(II) turned the fluorescence on, allowing for the titration of this cation using the G parameter of a digital picture taken to the discs. The limits of detection and quantification were 29 and 87 µg/L, respectively. Furthermore, we measured the concentration of Zn(II) even in the presence of other cations, detecting no significant interferences. Thus, in a further step, we obtained the concentration of Zn(II) from 15 commercial pet food samples, ranging from 19 to 198 mg/kg, following a simple extraction procedure and contacting the extractant with our sensory discs. These results were contrasted with that obtained by ICP-MS as a reference method., Spanish Agencia Estatal de Investigación (State Research Agency) (grant PID2020-113264RB-I00/AEI/10.13039/501100011033).

The aim of this study was to investigate the phytochemical composition and biological properties of Tunisian propolis from four different regions: Kasserine, Béja, Kèf and Monastir. Ethanolic extracts of propolis were prepared using two extraction methods; solvent and ultrasonic extraction. Total phenolics, flavonoids, ABTS free radical and hydroxyl radicals scavenging abilities, anti-inflammatory, anti-hypertensive, as well as antimicrobial activities of propolis extracts were determined. Identification and quantification of phenolic and flavonoid compounds were performed by using both HPLC-UV and HPLC-ESI-MS. The results revealed high contents of total phenolics and flavonoids and polyphenols extraction was more efficient by sonication. Caffeic acid phenethyl ester (CAPE), galangin, and genistein were the major identified compounds. Antihypertensive activity, evaluated in propolis extracts for first time by HPLC-UV, was higher than 90% for all extracts. Tunisian propolis is an important natural source of polyphenols and flavonoids. The best extraction method was ultrasonic for antioxidants and most of biological activities; conventional method seems to be more suitable for anti-inflammatory activity. Propolis from Béja contains the highest amount of antioxidants and have a stronger potential biological activities. Tunisian propolis could be, therefore, a promising raw material for food and pharmaceutical industry.

A new original application for a polyacrylic film based on the monomers 2-(dimethylamino)ethyl methacrylate (NNDA), 2-hydroxyethyl acrylate (2HEA) and methylmethacrylate (MMA) as a starch azure container has been set up for a simple determination of honey diastase activity. The proposed method is based on the correlation of reducing sugars generated during the enzymatic process with the Schade reference assay. The polyacrylic film is charged with starch azure acting as a container for this substance; thus, the starch does not interfere in the measurement of reducing sugars, so that the diastase activity is easily calculated. The method has been contrasted with Schade method, showing good correlation and differences under 0.4% between methods in some honey samples. The polyacrylic film has great potential for the routine honey diastase activity assessment in small laboratories, dramatically reducing analysis time and cost., FEDER (Fondo Europeo de Desarrollo Regional), and both the Spanish Ministerio de Economía, Industria y Competitividad (MAT2017-84501-R) and the Consejería de Educación—Junta de Castilla y León (BU306P18 and BU041G18)

A thorough updated review of both standardized and the most used and novel analytical methods for the analysis of honey is presented. The methodologies applied to honey in the analysis of the physical parameters (electrical conductivity, rheological properties, specific rotation, color and water activity), the analysis of the properties and the most important components of honey (moisture, sugars, enzymes, HMF, types of acidity and pH, formol index, insoluble solids, organic acids, proteins, amino acids, vitamins, minerals, volatile and semi-volatile compounds and polyphenols), and the antioxidant and antimicrobial activities are described. Finally, the most applied methods for multicomponent analysis and/or for honey authenticity verification (both the botanical and/or geographical origin honey classification and the detection of honey adulteration) are provided.

Polyphenols are secondary plant metabolites playing a major role as potentially functional components. They can also be used for honey authentication. This review gathers the recent literature refe...

We have developed a new method for the rapid (2 h) and inexpensive (materials cost 0.02 €/sample) "2-in-1" determination of the total phenolic content (TPC) and the antioxidant activity (AOX) in honey samples. The method is based on hydrophilic colorimetric films with diazonium groups, which react with phenols rendering highly colored azo groups. The TPC of the sample is correlated to its trolox equivalent antioxidant capacity (TEAC). The intensity of the color allows us to determine both TPC and TEAC of the sample by the analysis of a picture taken with a smartphone that is analysed by the use of the color-definition-parameters (RGB). The controlled light conditions and the systematic use of the same camera avoid the periodical calibration of the system improving the efficiency of the method. Thus, it is a simple method carried out by non-specialized personnel and it involves much lower money and time investment compared to traditional methods.

Nowadays, researching potentially functional properties of honey such as antimicrobial activity is interesting due to the overwhelming problem of bacteria strains resistant to antibiotics, and the expected higher value for honey that consumers constantly demand. In this research, we compared three different methods (agar dilution, broth dilution, as well as agar well diffusion), to analyse honey's antimicrobial activity against Staphylococcus aureus, using 56 unpasteurized honeys from different botanical origins. Agar well diffusion method showed to be a rapid and low cost screening method, using less medium and material, to distinguish the samples with and without antibacterial activity. Agar dilution and broth dilution procedures gave similar values. However, the latter proved to be faster and much more informative, providing with minimal antimicrobial and bactericidal concentrations. Higher values of antimicrobial activities were found in honeydew honeys, polyfloral honeys, Calluna vulgaris and Erica spp. honeys. Conversely, Lavandula spp. samples showed lower antimicrobial activity against Staphylococcus aureus.

We have prepared high-performance functional aromatic polyamides with sensory pendant groups toward amines. These polymers are colourless. The pendant groups have bromonaphthalimide motifs that react with amines rendering coloured arylamines by nucleophilic aromatic substitution of the halide. Thus, these materials are colorimetric sensors toward amines. In the interest of saving costs, while having a sensory material with a high specific surface, cotton fabrics were coated, in order to render coated fibres as smart colorimetric labels toward amines. Moreover, as fish spoilage by microorganism increases the biogenic amines in food, we have applied the smart labels to visually follow the food spoilage. Also, a picture taken to the films allowed to obtain, in seconds, the digital colour definition parameters (RGB) that were correlated with the results of expensive and time-consuming conventional techniques used to obtain relevant food quality data, such as total amine concentration (treatment of the sample and HPLC), colony-forming unit (microbiological assays), total volatile basic nitrogen (TVB-N), and organoleptic test (sensory test). The smart labels are inexpensive, granting in seconds the visual qualitative evaluation of the food quality, or even quantitative, and they comply with the European food contact materials regulation., FEDER (Fondo Europeo de Desarrollo Regional), and both the Spanish Ministerio de Economía, Industsria y Competitividad (MAT2017-84501-R) and the Consejería de Educación—Junta de Castilla y León (BU061U16)

Propolis is a resinous vegetal exudate modified by bees, and is interesting as a preservative and potentially functional product. This work dealt with studying the common phenolic profiles and antioxidant capacities of 13 bee propolis from different geographical areas. Both hyaluronidase and angiotensin converting enzyme (ACE) inhibitory activities were also assessed and related when possible with particular phenolic compounds. High performance liquid chromatography-ultraviolet detection (HPLC-UV) analysis showed that every propolis contained p-coumaric acid (1.2&ndash, 12.2 mg/g) and ferulic acid (0.3&ndash, 11.0 mg/g). Pinocembrin, catechin, and caffeic acid phenethyl ester (CAPE) plus galangin were the main flavonoids. Antioxidant activities were higher than 280 &micro, mol trolox/g for trolox equivalent antioxidant capacity (TEAC), 0.099 mmol uric acid/g for radical-scavenging effect on hydroxyl radicals, and 0.19 mg/mL for half maximal inhibitory concentration (IC50) of antioxidant activity against superoxide anion radical. Working with solutions of 10 mg/mL propolis, hyaluronidase inhibitory activity ranged between 0% and 68.20%, being correlated to ferulic acid content. ACE inhibitory effect determined by HPLC was higher than 78%, being correlated with catechin and p-coumaric acid. Therefore, propolis could be useful for food, pharmaceutical, and cosmetic companies, also helping to reduce risk factors for diseases related to oxidative damage, inflammatory processes, and hypertension. This research also highlights the necessity for harmonized analysis methods and the expression of results for propolis.

This research was aimed to study the sugar composition of fifty-four representative artisanal honeys from the northern Iberian plateau. Moisture, specific rotation, and crystallization indexes were also determined. Sugars were analyzed by gas chromatography-flame ionization detector (GC-FID) after Pourtallier´s derivatization procedure. Fourteen carbohydrates were reliably quantified: two monosaccharides, five disaccharides, six trisaccharides and one tetrasaccharide. Honeydew honeys showed the highest disaccharides (6.71%) and trisaccharides (1.81%) averages and the lowest monosaccharides (63.10%) average, in contrast to heather honeys that had the lowest disaccharides (4.93%) and trisaccharides (0.69%) averages and the highest monosaccharides (70.96%). Chestnut honeys possessed low concentrations of monosaccharides, sucrose, trehalose, and trisaccharides. Clover and lavender honeys possessed high monosaccharide and disaccharide percentages. As expected, lavender samples showed the highest sucrose concentrations (0.05–5.18%). Isomaltose contents were particularly high in honeydew (1.17–2.49%) and chestnut (1.34–1.74%) samples, and low in lavender (0.6–1.16%) honeys, the latter also being low in raffinose (0.01‒0.05%). Moisture percentages (14.4–18.6%) indicated optimum honey ripeness. Averages for all groups of samples were levorotatory. In contrast to honeydew and chestnut honeys, lavender samples showed the fastest granulation tendency. In the analyzed honeys, the higher the percentage of isomaltose was, the lower the crystallization tendency the honeys exhibited., Junta de Castilla y León” (Spain) for supporting this research under the project BU007A08

Propolis is a natural bee hive product with potential functional activities. Nowadays, many propolis products are available on the market, including cosmetics and food commodities. However, it is still unknown if edible products with propolis are fully accepted by consumers and are thus commercially viable, due to the bitter and resinous flavor and taste of propolis. This work is focused on the design of a “honey with propolis” foodstuff that can be welcomed by consumers, and, if possible, provide added benefits compared to the honey itself. Propolis tinctures containing three different concentrations of ethanol and times of maceration were prepared, giving the best results with 90% ethanol and two days of maceration. Then, in order to study the maximum amount of propolis in honey that could be accepted by a representative group of consumers, a forced choice paired comparison preference test with 69 people was carried out, giving the best results with a honey product containing 0.3-0.5% propolis extract. ...

Evolution of fructose and glucose over 30 months was researched in sixty fresh and unheated samples of honey collected in areas with typical Continental and Oceanic climates. Samples were stored at room temperature and analysed every 5 months. Influence of induced granulation process was also studied. Evolution patterns of both sugars were similar for all samples. We observed that both monosaccharides decreased with time being the evolution highly dependent on the initial pH of the samples. The lower the initial pH, the greater the decrease of monosaccharides. Induced granulation showed no influence on the evolution of fructose and glucose. © 2009 Institute of Food Science and Technology.

A capillary zone electrophoresis method for the determination of inorganic anions and formic acid in honey samples was developed for the first time. The complete separation of chloride, nitrate, sulfate, phosphate, and formic acid was achieved with a simple electrolyte composed by 2 mM potassium dichromate as the carrier solution and background absorbance provider and 0.05 mM tetraethylenepentamine (TEPA) as electro-osmotic flow suppressor (pH 4.00). Injection was performed hydrostatically by elevating the sample at 10 cm for 10 s. The running voltage was -27 kV at 25 degrees C. Indirect UV absorption detection was achieved at 254 nm. The detection limit was in the range between 0.03 and 20 mg/kg, and the quantification limits ranged from 1.52 to 20.6 mg/kg. The calibration graphs were linear in the concentration range from the quantification limit to at least 2.5 g/kg for chloride, 0.25 g/kg for nitrate, 0.75 g/kg for sulfate, 1.50 g/kg for phosphate, and 0.75 g/kg for formic acid. Precision data in the honey samples analyzed showed repeatability and reproducibility relative standard deviations lower than 1.4 and 2.4% for migration time and lower than 1.8 and 4.3% for anion content, respectively. Recoveries of anions in honey samples analyzed ranged from 94.4 to 99.8%. Ten honey samples were analyzed to test the proposed method. Mean contents of 260.5, 3.93, 60.5, 139.4, and 209.3 mg/kg were found, respectively, for chloride, nitrate, sulfate, phosphate, and formic acid in analyzed honeys. These results agreed with literature data.

A rapid capillary zone electrophoresis (CZE) method with direct ultraviolet (UV) detection has been set up and developed to determine the most important nonaromatic organic acids in honey with a really simple treatment of the sample. The determination of oxalic, formic, malic, succinic, pyruvic, acetic, lactic, citric, and gluconic acids has been carried out in 4 min. The electrolyte composition was phosphate as the carrier buffer (7.5 mM NaH(2)PO(4) and 2.5 mM Na(2)HPO(4)), 2.5 mM tetradecyltrimethylammonium hydroxide (TTAOH) as electroosmotic flow modifier, and 0.24 mM CaCl(2) as selectivity modifier, with the pH adjusted at 6.40 constant value. The running voltage was -25 kV at a thermostated temperature of 25 degrees C. The injections were performed in hydrodynamic mode (30 s), and the detection mode was UV direct at 185 nm. Validation parameters of the method as detection and quantification limits, linearity, precision (repeatability and reproducibility), and recovery were also studied. The advantages related to the technique such as simplicity, short analysis times, and low consumption of chemicals as well as the good validation parameters obtained for this method permit it to be considered as adequate for routine analysis in honey.

Although organic acids represent less than 0.5% of honey's 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 honey's 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.

This paper describes, for the first time, the variation of apparent ethanol content during storage of 33 honey samples. Moisture content was determined by measuring refractive index at 20°C. Apparent ethanol content was determined in a double cuvette, according to a modification of the Boehringer–Mannheim enzymatic method. Four different types of apparent ethanol evolution were observed: constant increment, increment followed by decrease, values oscillation and constant decrease.

L-Malic acid determination has been carried out in honey using a direct enzymatic method. The sample solution was prepared from 2.5 g honey in 100 ml Milli-Q water. The enzymatic determination was measured spectrophotometrically at 340 nm, using glutamate-oxaloacetate transaminase and L-malate dehydrogenase. The direct method combines precision (CV was 3.5%, at worst), good recovery (100 ± 3.5%), zero interference, simplicity, and low cost (cost was reduced by 50% using a microtest). This direct enzymatic method was applied to 20 floral honeys of Galicia (northwestern Spain) and the results ranged between 94 and 596 mg kg-1 (mean 246 mg kg-1) of L-malic acid, which is in keeping with value ranges obtained by other authors. Different clarifications [as polyvinylpolypyrrolidone (PVPP), Carrez, Carrez with NaOH, Carrez with KOH, Carrez together with PVPP and activated charcoal] and a pair of controls have also been used but the precision and the recovery of direct enzymatic method of L-malic acid in honey did not improve.

The total d-gluconic acid (free d-gluconic acid and d-glucono-δ-lactone) content of 20 Galician (northwestern Spain) honeys has been determined using an enzymatic method. To the author's knowledge, this is the first time this method has been applied to honey. The solution of honey was adjusted to pH 10.5 with 0.1 N KOH; 10 min at room temperature was allowed for hydrolysis of d-glucono-δ-lactone to d-gluconic acid. After this, it was necessary to adjust to test pH (7.8) with 0.1 N HCl. With these conditions, there were no observed interference effects. The enzymatic determination was measured spectrophotometrically at 340 nm, using gluconate kinase and 6-phosphogluconate dehydrogenase. The method combines precision (% CV was 0.30, at worst), good recovery (99.8%), simplicity, and low cost because this cost was reduced by 60% using a microtest. The total d-gluconic acid content of the honeys analyzed ranges between 3.91 and 11.71 g/kg (mean = 7.37 g/kg), which is in keeping with value ranges obtained by ot...

The glycerol content of honey has been determined using a Boehringer Mannheim enzymatic method simplified for this purpose. The solution of honey was employed directly, without clarification and without addition of NaOH solution. With these conditions, there were no observed interference effects. It is necessary to use a 1.5 ml micro-cuvette. The enzymatic determination was measured spectrophotometrically at 365 nm using the enzymes in quadruple the quantities recommended by the supplier. The method combines precision, good recovery, sensitivity, simplicity and low cost.

Knowing the 'best-before period once opened' is of paramount importance for consumers, because it gives information about how long a given food keeps its quality. The hydroxymethylfurfural (HMF) content is related to honey's aging and heating. We researched the evolution of HMF of 60 unheated honeys originating from continental and oceanic climate areas, recording the moment at which the HMF increase begins to speed up. We also researched the influence of induced granulation on HMF evolution. All samples were stored at room temperature and analysed every 5 months throughout 30 months. Storage had an effect on HMF contents. On the contrary, induced granulation did not show any influence on this parameter. HMF constantly increased in all samples but much more markedly after 20 months. At 20 months, the percentages of samples with HMF higher than 40 mg/kg ranged between 2.9% and 8.0%. Nevertheless, at 25 months these percentages clearly increased, ranging from 22.9% to 72.0%. For honeys from both the continental and oceanic climate areas, taking HMF contents into account, 20 months could be proposed as the 'best-before period once opened'.

An improved method is reported for the determination of catalase activity in honey. We tested different dialysis membranes, dialysis fluid compositions and amounts, dialysis temperatures, sample amounts, and dialysis times. The best results were obtained by dialysis of 7.50 g sample in a cellulose dialysis sack, using two 3 L portions of 0.015 M sodium phosphate buffer (pH 7.0) as the dialysis fluid at 4 degrees C for 22 h. As in previous methods, catalase activity was determined on the basis of the rate of disappearance of the substrate, H202, with the H202 determined spectrophotometrically at 400 nm in an assay system containing o-dianisidine and peroxidase. Trials indicated that the best solvent for the o-dianisidine was 0.2 M sodium phosphate buffer, pH 6.1; the best starting H202 concentration was 3 mM; the best HCl concentration for stopping the reaction was 6 N; and the best sample volume for catalase measurement was 7.0 mL. Precision values (relative standard deviations for analyses of 10 subsamples of each of 3 samples) were high, ranging from 0.48% for samples with high catalase activity to 1.98% for samples with low catalase activity.

The purpose of this paper was to study and optimize both extraction and high-pressure liquid chromatography (HPLC)-UV detection procedures to develop a proper method for the determination of ascorbic acid content in cooked sausages. A simple and sensitive reversed-phase HPLC method for the NH2-bonded phase has been described for the determination of ascorbic acid content in cooked sausages. Various extracting agents were tested to solubilize the vitamin, with 5% (wt/vol) metaphosphoric acid giving the best results. Samples were chromatographed with UV detection at 248 nm on a 25-cm Spherisorb NH2 cartridge with a 0.4-cm inside diameter with a mixture of 0.02 M potassium phosphate buffer solution (pH 3.6) and acetonitrile (40:60, vol/vol) for the mobile phase. The method's precision within a day was 1.2%, and its precision between days was 3.8%. The detection limit was 1.6 mg/100 g. Recovery ranged from 91.4 to 96.2% for ascorbic acid added to meat samples. Twenty samples of six different products were analyzed in duplicate. For the samples analyzed, the mean value for ascorbic acid ranged between 21.555 and 24.899 mg/100 g of fresh weight.

Primary normal alcohols of 33 unpasteurized Galician (northwestern Spain) honeys have been determined as apparent ethanol contents. A modification of the Boehringer-Mannheim enzymatic method has been used. The solution of honey has been employed directly, neither clarified nor neutralized. Removal of interferences required absorbance measurements at 340 nm, by using the solution of honey with the solution of aldehyde dehydrogenase into the reference cuvette. Water is added to the reference cuvette and alcohol dehydrogenase suspension to the sample cuvette. The blanks are measured following the same procedure with redistilled water instead of sample solution. Ten replicate analyses of each of four samples with apparent ethanol levels of 13.5, 35.3, 50.1, and 141.8 mg/kg gave coefficient of variations of 1.74%, 0.48%, 0.34%, and 0.22%, respectively. The modified enzymatic method performed well in recovery experiments (recovery 100.1%). The apparent ethanol contents of 32 of the 33 honeys studied lay in the range 13.5‒50.1 mg/kg (mean 27.8 mg/kg); the remaining unspoiled honey had an apparent ethanol content of 141.8 mg/kg. © 1994, American Chemical Society. All rights reserved.

The glycerol content of 33 honeys of Galicia (northwestern Spain) has been determined using the Boehringer-Mannheim enzymatic method modified for this purpose. As far as we know, it is the first time this method has been applied to honey. Volumes of 0.5 mL of potassium hexacyanoferrate(II)-trihydrate solution (Carrez I) and zinc acetate-dihydrate solution (Carrez II) were used and, following clarification, about 4 mL of 0.1 N NaOH. The enzymatic determination was performed “spectrophotometrically” at 365 nm using pyruvate kinase, lactate dehydrogenase, and glycerokinase in double the quantities recommended by the supplier. The method combines precision (CV% less than 1.1%), good recovery (102.2%), sensitivity (30 mg/kg), simplicity, and low cost. The glycerol content of the honeys analyzed ranges between 50.0 and 366.2 mg/kg (mean 137.6 mg/kg), which is in keeping with values obtained by other authors using other methods (HPLC, GC). © 1993, American Chemical Society. All rights reserved.

Although organic acids represent < 0.5% of honey's 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.

An improved method is reported for the determination of catalase activity in honey. We tested different dialysis membranes, dialysis fluid compositions and amounts, dialysis temperatures, sample amounts, and dialysis times. The best results were obtained by dialysis of 7.50 g sample in a cellulose dialysis sack, using two 3 L portions of 0.015M sodium phosphate buffer (pH 7.0) as the dialysis fluid at 4°C for 22 h. As in previous methods, catalase activity was determined on the basis of the rate of disappearance of the substrate, H2O2, with the H2O2 determined spectrophotometrically at 400 nm in an assay system containing o-dianisidine and peroxidase. Trials indicated that the best solvent for the o-dianisidine was 0.2M sodium phosphate buffer, pH 6.1; the best starting H2O2 concentration was 3mM; the best HCl concentration for stopping the reaction was 6N; and the best sample volume for catalase measurement was 7.0 mL. Precision values (relative standard deviations for analyses of 10 subsamples of each of 3 samples) were high, ranging from 0.48% for samples with high catalase activity to 1.98% for samples with low catalase activity.