Pollen spectrum and physico‐chemical attributes of heather (Erica sp.) honeys of north Portugal

BACKGROUND: Honey legislation has been addressed to establish the minimum marketing level of the product and the need for consumer protection through correct denominations. Research oriented toward assessment of floral origin and physico‐chemical properties may increase the commercial value of these products. The characteristics of 23 unifloral honeys of Erica sp., from Portugal, were studied. Pollen features and some physicochemical parameters (moisture, ash, pH, free acidity, electrical conductivity, hydroxymethylfurfural content, apparent sucrose, reducing sugars and diastase activity) were determined. RESULTS: All honey samples can be classified as monofloral Erica sp., they gave a mean value of 56% of Erica pollen type. The families Fabaceae and Rosaceae provided the greatest number of pollen types with 8 and 4 pollen types each respectively. The second most important pollen type is Eucalyptus, present in 69.6% of the samples. All honey samples met the international physicochemical quality standards. The present study found a linear correlation (R = 0.996) between the ash content of honeys and their specific conductivity. CONCLUSION: All honey samples can be classified as monofloral Erica sp. Unifloral honeys are increasingly requested and appreciated, despite their higher prices. The samples were found to meet all major international honey specifications. Copyright © 2009 Society of Chemical Industry     

Characterisation of avocado (Persea americana Mill) honeys by their physicochemical characteristics

The quality of 12 avocado (Persea americana Mill) honeys from Spain was evaluated. Eight common physicochemical parameters were analysed, namely water content, pH, acidity (free, lactonic and total), sugar content, ash content and electrical conductivity. In addition, the honey samples were analysed using inductively coupled plasma optical emission spectrometry (ICP‐OES), and six minerals were quantified for each honey, namely potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), phosphorus (P) and sulphur (S). Most samples showed proper maturity considering the medium water content (mean 17.7%). The total acidity (below 50 meq kg^?1 except for one sample) indicated absence of undesirable fermentation; also, the mean pH of around 4.77 is usual in this kind of honey. The values for ash content and electrical conductivity were high (0.77% and 798 µS cm^?1 respectively) and typical of dark honeys. K was the predominant mineral (accounting for 73% of the total minerals quantified), followed by Na (10%). Copyright © 2004 Society of Chemical Industry     

Unifloral honeys of the province of Buenos Aires,Argentine

Samples of 63 unifloral honeys of the province of Buenos Aires, Argentina, from Eucalyptus spp, Lotus spp, Helianthus annuus, Melilotus albus, Brassicaceae, clovers other than Lotus and Melilotus, and Sagittaria montevidensis, were obtained by cold extraction at the laboratory. The frequencies of occurrence of pollen types, and the moisture, hydroxymethylfurfural, ash, acidity and proline contents were determined. Electrical conductivity, pH and colour were also analysed. Honey presented a high percentage (about 40%) of unifloral honey. The most frequent unifloral honeys were from Eucalyptus spp, Lotus spp and Helianthus annuus. Samples had a low pollen diversity with six to 19 pollen types, the most important nectariferous taxa being those that characterized the unifloral honeys. All samples presented moisture, hydroxymethylfurfural, ash and free acidity contents according to international standards. The colour of the honey was from water white to light amber, and all samples had a very low ash content. Significant differences at the 5% level in the hydroxymethylfurfural content, electrical conductivity, colour and proline content were observed among honeys from different floral origins. However, a high variability between samples from the same floral origin was observed, indicating that other factors such as accompanying pollen and geographical origin affect the physicochemical characteristics of honey. Copyright © 2005 Society of Chemical Industry     

Pattern of pH and electrical conductivity upon honey dilution as a complementary tool for discriminating geographical origin of honeys

Seven physicochemical parameters (water content, ash, water activity, free, lactone and total acidity, pH and electrical conductivity) were analyzed in 19 nectar honeys of different floral origin and from several regions of Argentina. In addition, the pattern of electrical conductivity and pH upon honey dilution were also studied with increasing honey concentration, the pH values decreased exponentially. The dependence of specific electrical conductivity (κ) on honey concentration was characterized by a maximum at a κ value (κ_max) corresponding to a dry solids of honey concentration of 30–35% (w/w). For a given geographical region, ash and acidity values were useful for discriminating honeys of different floral origins. The most adequate parameters for discriminating honeys of different geographical origin were those which described the patterns of pH and electrical conductivity with changes of honey concentration.     

Efficiency of the FT‐IR ATR spectrometry for the prediction of the physicochemical characteristics of Melipona subnitida honey and study of the temperature's effect on those properties

The efficiency of ATR FT‐IR spectrometry was compared with recommended methodologies for physicochemical parameters of eighteen samples of Melipona subnitida honey. Significant differences were found between the values obtained using those techniques for hydroxymethylfurfural, ash and electrical conductivity. The results for the other parameters did not differ significantly, suggesting that this rapid and nondestructive methodology may predict parameters usually used to assess honeys’ quality. The effects of different storage conditions (room temperature, fridge and freezer) on the quality parameters of the product stored during 12 months were studied. Darkening of the honey was observed, particularly in the fridge and freezer. However, the changes occurring in the honey kept on the fridge were not statistically different from those occurring in the product kept on the freezer, except for free acidity. The results obtained for the honey stored at room temperature, best way to preserve, differed significantly from those obtained for the honey kept under the other conditions.     

Physicochemical attributes and pollen spectrum of Portuguese heather honeys

The qualities of selected honey samples of “Serra da Lousã” (Portugal) from three consecutive harvests (20 samples from each harvest) were evaluated by determing the pollen spectrum and physicochemical attributes. The following determinations were carried out: moisture, electrical conductivity, hydroxymethylfurfural, diastase activity, pH, acidity (free, lactone and total), formol number, reducing sugars, apparent sucrose, insoluble material and ash. The samples were found to meet all major national and international honey specifications. Honeys were considered to be monofloral whenever the dominant pollen was found to be over 45% of total pollen. From the 60 studied samples, 70% were monofloral honeys from Erica sp., 17% monofloral honeys from Ericaceae (Erica sp. and Calluna vulgaris (L.) Hull) and 13% multifloral honeys with a high percentage of Erica sp.     

Aroma profile and physico‐chemical properties of artisanal honey from Tabasco,Mexico

The aim of this work was to characterise, physico‐chemically, sugar composition and aroma profile of ten honey samples collected by small producers during two seasons and produced in different agricultural ecosystems from Tabasco State (Mexico). The mean values obtained for the physico‐chemical parameters were: pH 3.63; 19.25% moisture; 78.8°Brix sugar; 0.64% ash; 0.25 mS cm^?1 electrical conductivity and 0.58 water activity. Based on colour parameters, Tabasco honeys can be placed in the group of dark honeys. In the analysed samples; fructose was the major sugar (39.45%), followed by glucose (35.74%) while sucrose only represented 2.93%. The volatile profiles of the ten honey samples were obtained by gas chromatography‐mass spectrometry. All the honeys were characterised by their high contents of benzene and furan‐related compounds. As a result, artisanal honeys from Tabasco (Mexico) can be considered to present a good level of quality.     

Characterization and classification of Thymus capitatus (L.) honey according to geographical origin based on volatile compounds,physicochemical parameters and chemometrics

Greek thyme honeys (Thymus capitatus L.) were characterized and classified according to geographical origin based on the determination of volatile compounds and physicochemical parameters using MANOVA and Linear Discriminant Analysis. Forty two thyme honey samples were collected during the harvesting period in 2011 from 5 different regions in Greece known to produce thyme honey of good quality. The analysis of volatile compounds was performed by Headspace Solid Phase Microextraction coupled to Gas chromatography/Mass spectroscopy. Forty seven volatile compounds were identified and semi-quantified. Physicochemical analysis included the determination of pH, free, lactonic and total acidity, electrical conductivity, moisture, ash, lactonic/free acidity ratio and color parameters: L*, a*, b*. Using 9 volatile compounds and 11 physicochemical parameters the honey samples were satisfactorily classified according to geographical origin using volatile compounds (64.3% correct prediction), physicochemical parameters (92.7% correct prediction), and the combination of both (92.9% correct prediction).     

Sugar profile and physicochemical properties of Ethiopian monofloral honey

Three hundred twenty honey samples were collected from Ethiopia, and categorized into nine monofloral honeys using melissopalynology. Theses monofloral honeys were investigated for their sugar profile, physicochemical properties, and quality of honeys. Sugars (fructose, glucose, sucrose, maltose, turanose, and isomaltose) were identified using high-performance liquid chromatography and physicochemical properties (moisture, water activity, pH, acidity, ash, minerals, conductivity, colour) using the Harmonized Method of the International Honey Commission. Moisture and water activity showed a strong regression coefficient (r² = 0.92). Moisture content alone did not sufficiently describe the quality of honey during storage and processing.     

Characterisation of Slovenian honeys on the basis of sensory and physicochemical analysis with a chemometric approach

The purpose of this study was sensory and physicochemical characterisation of Slovenian honeys with a chemometric approach. Honey samples were obtained from the beekeepers in different natural geographical macroregions of Slovenia. The sensory characteristics of the seven main types of Slovenian honeys are described, together with the physicochemical analyses. The average results of electrical conductivity (0.19–1.61 mS cm^?1), pH (4.01–5.51), free acidity (13.3–30.9 meq kg^?1), proline content (317–558 mg kg^?1), protein content (1.70–3.53 g kg^?1), optical rotation (–19.6 to 12.6), phenolic content (44.9–232.5 mg GAE kg^?1) and antioxidant activity [69.6–456.4 μm Fe(II)] show wide variability among analysed honey types. Statistically significant differences were obtained among different honey types, generally lower values of the analysed parameters were determined in the light honeys, as the acacia, linden and multifloral honeys, while the higher values are characteristic for darker honeys, as the chestnut, fir, spruce and forest honeys. Linear discriminant analysis was performed to classify the honey samples according to their botanical origin and proved that physicochemical parameters analysed can provide enough information for the classification and distinction of acacia, linden, multifloral and chestnut honeys, and the group of honeydew honeys (fir, spruce and forest honeys).     

Comparative study of the physicochemical and palynological characteristics of honey from Melipona subnitida and Apis mellifera

Twenty‐four samples of Apis mellifera honey and twenty‐four samples of Melipona subnitida (Jandaira) honey were collected in the northeast of Brazil. Moisture, hydroxymethylfurfural, free acidity, insoluble solids in water, diastase activity, ashes, electrical conductivity, proteins, lipids, total carbohydrates, energy and sugars were the parameters analysed. The efficiency of the qualitative tests (Fiehe's test, Lugol's reaction, Lund's reaction) was tested. Pollen types and the corresponding plant species were identified in all samples (3 in Apis and 1 in Melipona). Apis mellifera honey samples demonstrated parameters in accordance with the Brazilian Legislation, while the Melipona subnitida honey samples displayed moisture (24.80%) and diastase activity (null) in discordance with the established by the regulation for Apis mellifera honeys. Apis honey samples presented higher values of electric conductivity (284.00 μS cm^?1) than the obtained from the Jandaira honey samples (102.77 μS cm^?1) as well as a darker colour (26.67 mmPfund) when compared with Jandaira honey (7.00 mmPfund). The concentration of the glucose, fructose and sucrose was higher in the Apis honeys than in the Jandaira honey. The characteristics of the two types of honey were very different, highlighting the need of developing specific legislation for stingless bees' honey.     

Differentiation of blossom and honeydew honeys using multivariate analysis on the physicochemical parameters and sugar composition

Multivariate analysis was applied on physicochemical parameters (moisture, water activity, electric conductivity, colour, hydroxymethyl furfural, acidity, pH, proline, diastase and invertase), sugar composition (fructose, glucose, sucrose, maltose, isomaltose, trehalose, turanose and melezitose) and palinological parameters determined in blossom and suspected honeydew honeys in order to differentiate them. The majority of the physicochemical, sugar composition and palinological parameters evaluated presented significant differences in the mean values between the suspected honeydew and blossom honeys, with the exception of moisture, water activity, diastase, fructose and maltose. Blossom honey samples tend to differentiate from the suspected honeydew honeys after applying factor analysis on the physicochemical parameters and sugar composition. Stepwise linear discriminant analysis allows the correct classification of all blossom honeys, and only one honeydew honey was erroneously included as blossom honey. So, the use of multivariate analysis on physicochemical parameters and sugar composition can be a useful tool to differentiate these types of honeys.     

Characterization of artisanal honeys from Madrid (Central Spain) on the basis of their melissopalynological,physicochemical and volatile composition data

Forty-six artisanal honey samples, from different places of Madrid province (Central Spain), were characterized on the basis of their melissopalynological, physico-chemical and volatile composition data. Results were submitted to principal component analysis and stepwise discriminant analysis in order to evaluate the existence of data patterns and the possibility of differentiation of Madrid honey samples according to their botanical source (honeydew, nectar) and geographical collection place (mountain, plain). Colour, electrical conductivity, acidity, ash content and pH were the physicochemical parameters with higher discrimination power in the differentiation of nectar and honeydew honeys while, among the volatile components, concentrations of borneol, 1-(2-furanyl)-ethanone and 3-hydroxy-2-butanone were the most discriminant variables. In the differentiation of honey samples from mountain and plain zones, 2,3-butanediol and 1-(2-furanyl)-ethanone were the most significant volatiles, while physicochemical data were not useful for distinguishing between collection places. The honeydew percentage in a honey sample (HD%) was estimated from physicochemical measures and also from volatile concentrations; 2,3-butanediol, 3-hydroxy-2-butanone, 1-hydroxy-2-propanone and 1-(2-furanyl)-ethanone were found to be related to HD%.     

Characterization and Discrimination of the Floral Origin of Sidr Honey by Physicochemical Data Combined with Multivariate Analysis

Sidr honey represents one of the most expensive monofloral honeys worldwide. The quality control of such honey types usually depends on pollen analysis or comparison of physicochemical characters. In the presented work, 38 different honey samples of which 13 represented genuine Sidr (Ziziphus spina-christy) honey samples were collected from various areas of Yemen. All samples were characterized by physicochemical parameters including moisture content, pH, electrical conductivity, and free acidity. The physicochemical data was subjected to multivariate data analysis including principal component analysis (PCA) and hierarchical cluster analysis (HCA). The development of partial least square discriminant analysis (PLS-DA) model on validation gave 100 % correct classification of the test set samples. All tested honey samples were within the level permitted by the international standards for honey quality. The application of the discriminant technique PLS-DA presented excellent potential for discriminating the botanical origin of Yemeni Sidr honey from other non-Sidr samples and may serve as a discriminant model to be applied to other honey types worldwide.     

Characterisation of Argentinean honeys and evaluation of its inhibitory action on Escherichia coli growth

The aim of this work was to evaluate the physicochemical, sensory and Escherichia coli growth inhibitory characteristics of honey of different botanical sources from two geographic origin of Argentina. Honeys were obtained from apiaries located in two zones. The floral identification of honeys allowed to clustered them as monofloral, mixed and polyfloral honeys. The study of the physicochemical parameters such as colour, free acidity, pH and moisture showed that the last one reflected significant differences between honeys. These differences were markedly reflected in the average values of moisture content for each zone, being 18.96% and 14.29% to centre and east zone, respectively. In general, honeys evaluated presented an inhibitory effect on the E. coli growth at different periods of time (bacteriostatic action). Only, two of the samples would show a bactericide action against E. coli at 48 h of incubation. Honeys with higher non‐hydrogen peroxide activity, were collected from a same geographic place at the same season of year, showing a relationship between the antimicrobial activity and the geographic origin, which could be associated with the typical flora of the place.     

Differentiation of Greek Thyme Honeys According to Geographical Origin Based on the Combination of Phenolic Compounds and Conventional Quality Parameters Using Chemometrics

The aim of the present study was to differentiate Greek thyme honeys according to geographical origin, based on phenolic compound content and conventional physicochemical parameters using MANOVA and Linear Discriminant Analysis. Thirty-five thyme honey samples were collected during the harvesting period 2011 from four different regions in Greece (Irakleio, Hania, Kefalonia and Lakonia) known to produce thyme honey of good quality. The analysis of phenolic compounds (quercetin, myricetin, kaempferol, chrysin, and syringic acid) was performed by high pressure liquid chromatography. Conventional quality parameter analysis included the determination of the following: pH, free, lactonic and total acidity, electrical conductivity, moisture, ash, as well as lactonic/free acidity ratio and colour parameters L*, a*, b*. Using five phenolic compounds and 11 conventional quality parameters, thyme honey samples were satisfactorily classified (91.2 % correct prediction) according to geographical origin.     

Antioxidant capacity of Spanish honeys and its correlation with polyphenol content and other physicochemical properties

Thirty‐six Spanish honeys of different floral origins (nectars and honeydews) were assessed to estimate their radical‐scavenging capacity against the stable free radical DPPH (1,1‐diphenyl‐2‐picrylhydrazyl), their ability to inhibit enzymatic browning in apple homogenate and their clarifying effect on apple juice. These capacities were evaluated spectrophotometrically. Physicochemical parameters such as pH, acidity, net absorbance, electrical conductivity and total polyphenol content of the samples were also evaluated. It was observed that all these parameters presented a strong correlation with radical‐scavenging capacity, whereas antibrowning capacity had a low correlation with conductivity and no correlation with honey pH. When data of nectar and honeydew honeys were evaluated separately, net absorbance and honey acidity seemed to be good parameters to evaluate the antioxidant activity of nectar honeys; however, in honeydew honeys there were only relationships between radical‐scavenging activity and honey conductivity and between browning inhibition of homogenates and total acidity. In general, honeydew honeys showed higher antioxidant capacities than nectar honeys. Copyright © 2007 Society of Chemical Industry     

Chemometrics Classification of Argentine Clover and Eucalyptus Honeys According to Palynological,Physicochemical, and Sensory Properties

Palynological, physicochemical, and sensory methods were applied to ascertain the most discriminant variables for honey characterization. Fifteen physicochemical parameters, six indicators of antioxidant capacity and eight sensory attributes were considered. Clover and eucalyptus honeys were differentiated when the linear discriminant analysis was applied. Electrical conductivity, sugars, ferric ion reducing, and Trolox equivalent antioxidant capacity were the most discriminant variables. Odor and color intensities were the sensory attributes scoring the major differences between honeys. The canonical correlations technique pointed out that differences were related primarily to the content of pollen from Trifolium, Medicago sativa, and Lotus. These standards of quality provide a differentiating tool to classify unifloral honeys.     

Volatile fraction composition and physicochemical parameters as tools for the differentiation of lemon blossom honey and orange blossom honey

BACKGROUND: Volatile fraction profile and physicochemical parameters were studied with the aim of evaluating their effectiveness for the differentiation between lemon blossom honey (Citrus limon L.) and orange blossom honey (Citrus spp.). They would be useful complementary tools to the traditional analysis based on the percentage of pollen. RESULTS: A stepwise discriminant analysis constructed using 37 volatile compounds (extracted by purge and trap and analysed by gas chromatography–mass spectrometry), and physicochemical and colour parameters (diastase, conductivity, Pfund colour and CIE L*a*b*) together provided a model that permitted the correct classification of 98.3% of the original and 96.6% of the cross‐validated cases, indicating its efficiency and robustness. This model proved its effectiveness in the differentiation of both types of honey with another set of batches from the following year. CONCLUSION: This model, developed from the volatile compounds, physicochemical and colour parameters, has been useful for the differentiation of lemon and orange blossom honeys. Furthermore, it may be of particular interest for the attainment of a suitable classification of orange honey in which the pollen count is very low. These capabilities imply an evident marketing advantage for the beekeeping sector, since lemon blossom honey could be commercialized as unifloral honey and not as generic citrus honey and orange blossom honey could be correctly characterized. Copyright © 2011 Society of Chemical Industry     

Correlations of sensory parameters with physicochemical characteristics of Argentinean honeys by multivariate statistical techniques

Honey acceptability is mainly determined by its colour, crystallisation degree and aroma. In the present work, the sensory characteristics and physicochemical parameters of Argentinean honeys from different ecoregions were analysed. Moisture content, Pfund colour, diastase activity, hydroxymethylfurfural content, electrical conductivity, sugar profile and volatile compounds were analytically determined in honey samples, while sensory characteristics (crystal size, fluency score, sweetness, persistence, granularity, crystallisation, colour intensity and aroma) were evaluated by a trained panel. Significant correlations were found between honey crystallisation degree and hydroxymethylfurfural content and diastase activity (P ≤ 0.05). It could be confirmed that honey crystallisation interferes with the visual perception of colour. Floral, fresh fruit, ripe fruit, balsamic and wood aromas could be successfully linked to honey volatile profile (P ≤ 0.05). These results demonstrate that the parameters that could best guarantee the consumers’ preference can be successfully associated with the chemical composition of honey by multivariate statistical analysis.