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).     

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     

Geographical characterisation of multifloral honeys from the Marche region (Italy) according to their antioxidant activity and colour using a chemometric approach

Multifloral honeys produced in the Marche region (Italy) were analysed leading to the antioxidant and colour characterisation of this type of regional honeys: the antioxidant activity was determined measuring total phenolic content (TPC), and using ABTS and DPPH assays. The elaboration of data with multivariate analyses enabled differentiation of the geographical origin of honey samples, namely as coming from the Mid/Coastal Hilly or from the High Hilly/Submountain belt of the Marche region. The cluster analysis applied to a selection of samples divided honeys belonging to the Mid/Coastal Hilly belt into three groups showing low, medium and high antioxidant activity and in part located in different areas of the region. Finally, using data of unifloral honeys from the Marche region previously determined, it was possible to have an indication of the prevalent nectar contained in most of the multifloral honey samples harvested in 2012 in the Marche region.     

Jujube Honey from China: Physicochemical Characteristics and Mineral Contents

We investigated and compared the physicochemical properties (moisture, color, ash, pH, electrical conductivity, free acidity, lactonic acidity, total acidity, fructose, glucose, sucrose, diastase activity, and HMF) and mineral contents (Al, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, As, Cd, Pb, and Zn), as well as total proline and total protein contents of 23 jujube honey samples collected from different regions of China. The mineral content was determined by inductively coupled plasma‐optical emission spectrometry (ICP‐OES). The physicochemical values were in the range of approved limits (conforming to EU legislation) in all 23 samples. The physicochemical properties of jujube honey showed significant variations among samples. The mean pH value of the jujube honeys was 6.71. The most abundant minerals were potassium, calcium, sodium, and magnesium, ranging between 1081.4 and 2642.9, 97.1 and 194.2, 7.79 and 127.8, and 10.36 and 24.67 mg/kg, respectively, and potassium made up 71% of the total mineral content. This study demonstrated remarkable variation in physicochemical parameters and mineral contents of jujube honey, mainly depending on its geographic source.     

基于代谢组学技术的神农百花蜜真实性鉴别

目的 通过非靶向代谢组学鉴定真实神农百花蜜特征标志物,并建立基于偏最小二乘（partial least squares, PLS）的神农百花蜜判别模型。方法 采用基于超高效液相色谱-四极杆串联飞行时间质谱（ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry, UPLC-Q-TOF-MS）的非靶向代谢组学方法分析神农百花蜜样本,利用V+S图、聚类热图和受试者工作特征（receiver operating characteristic, ROC）曲线确定真实神农百花蜜特征标志物,利用神农百花蜜特征标志物构建PLS判别模型。结果 多元统计分析结果显示,主成分分析（principal component analysis, PCA）和正交偏最小二乘-判别分析（orthogonal partial least squares discriminant analysis, OPLS-DA）可以实现真实神农百花蜜和对照组蜂蜜的区分;分别在正、负离子模式下筛选出了19种和27种差异代谢物,其中13种差异代谢物在真实神农百花蜜中的含量较高,可作为其潜在标志物;通过ROC曲线评估,确定了女贞甙、鸟苷、半胱氨酰-苯丙氨酸和4''-O-甲基甘醇W等13种化合物可以作为真实神农百花蜜的特征标志物;利用神农百花蜜特征标志物建立PLS判别模型,对未知样本的鉴别准确率可以达到100%。结论 非靶向代谢组学技术在神农百花蜜的鉴别中具有可行性。     

Characterization of Spanish honeys with protected designation of origin "Miel de Granada" according to their mineral content

Honey attributes such as geographical origin or specified botanical sources often command a premium price due to their organoleptic or pharmacoactive properties. "Miel de Granada" is a highly quality product with protected designation of origin (PDO) which includes six monofloral honeys and two multifloral honeys. Our objective was the characterization of "Miel de Granada" according to their metal content. Metal content was specific enough and allowed discrimination from honeys of different botanical and geographical origins and confirmed the authenticity of PDO labelling as Granada product with the determination of only five elements (K, Na, Ca, Mg and Zn). Chemometric techniques as cluster analysis and ANOVA were used to classify honeys according to their botanical and geographical origin in the metal data. Metal content marks the differences in honey samples and can be used as a tool to assess the quality of honeys. ANOVA showed significant differences among rosemary honeys from different geographical areas despite the botanical factor weight. Our research contributes to the groundwork studies to determine the geographical origin of Spanish honeys.     

Physico chemical and bioactive properties of honeys from Northwestern Argentina

Honey is used for its nutritional and functional properties. The Argentinean Northwest is a region with a growing potential for honey production, but up to now, few physicochemical and biological studies have been carried out. The aim of this study is to characterize monofloral (Prosopis sp and Citrus lemon) and multifloral honey samples from the Argentinean Northwest from a physicochemical and functional standpoint. The results showed that the honeys had good properties of stability and freshness. The highest content of flavonoid and phenolic compounds correspond to multifloral honeys. A positive correlation was observed between colour intensity and flavonoid or phenolic compounds content (R² = 0.98 and R² = 0.92, respectively). The flavonoids, chrysin and pinocembrin were present in all samples analyzed, while hesperidin and hesperetin were numerically more important in lemon honey (>1 mg/kg), providing a valuable marker of botanical origin.The highest antioxidant activity against ABTS radical cation was detected in the darkest honey samples. All tested honeys showed antibacterial activity with MIC values between 0.10 and 0.25 g/mL on Gram-positive and Gram-negative antibiotic resistant bacteria. Neither pH nor osmolarity affected bacterial growth. The phenolic compounds and hydrogen peroxide were responsible for antimicrobial activity by bioautographic assays.The antioxidant and antimicrobial properties found in honeys from the Argentinean Northwest make them products of high added value and excellent quality.     

Analysis of minority honey components: Possible use for the evaluation of honey quality

The minerals (Al, B, Ca, Cu, Mg, Mn, Ni, Zn) of 24 authentic Czech nectar and honeydew honey samples (2003 and 2004 harvests) were determined, to find the relationship between their content and the origin or type of honey. The concentrations of analytes in the digests, obtained via optimised dry decomposition of honey samples, were measured by flame atomic absorption spectrometry (F-AAS), as well as optical emission spectrometry with inductively coupled plasma (ICP-OES). With regard to its speed of analysis and cost, ICP-OES was the more favourable method. By combining the analytical data and electrolytic conductivities of samples, the honey samples could be divided into two groups – honeydew honeys and nectar honeys. Like Slovak and Polish honeys, samples of Czech honeys had higher nickel levels than honeys originating from other parts of the world.     

Vitamin C and sugar levels as simple markers for discriminating Spanish honey sources

In this work, 7 Spanish honeys with different botanical origins were studied. The honey origins were rosemary, chestnut, lavender, echium, thyme, multifloral, and honeydew. The chemical compounds determined were ascorbic acid (vitamin C), hydroxymethylfurfural, and major sugar contents (glucose and fructose). The physicochemical parameters, pH, conductivity, moisture, free acidity, and color, were also measured. Vitamin C is an important antioxidant in food, and the possibility to use it as discriminate parameter among different honeys was studied. The determination of vitamin C in honey samples was carried out by 2 different methods, volumetric and chromatographic comparing the results by both statistically. Vitamin C content was higher in thyme honeys than in the other types; however a wide dispersion in the values was found. Through a linear discriminant analysis (LDA), conductivity, glucose, fructose, and vitamin C content were the most important discriminant parameters. PRACTICAL APPLICATION: Vitamin C content in different honey sources has been determined by a simple and rapid chromatographic method (less than 3 min) in honeys from 6 botanical origins. The results together with glucose and fructose content and some physicochemical parameters have been studied in order to discriminate the botanical origin of honeys and in the future certified their quality. A statistical LDA was applied to the data, and differentiation of honey sources was possible with very good agreement. The vitamin C content found in thymus honeys was significantly higher than in other types. This fact makes vitamin C a special marker for thymus honeys that have a higher antioxidant effect than the others giving it special properties. The identification of honey sources is essential for beekeepers in order to certify honeys for consumers.     

Physicochemical and melissopalynological characterization of Estonian summer honeys

The samples of 14 honeys, retained from Estonian beekeepers, were analyzed for parameters such as pH, moisture content, free acidity, electrical conductivity, diastase activity, hydroxymethylfurfural (HMF) content and mineral content, including sodium (Na), potassium (K), magnesium (Mg) and calcium (Ca). Fructose, glucose and disaccharide content were also identified and fructose/glucose ratio was calculated. In addition melissopalynological analyses were carried out for characterization of honeys. The mean values of analyzed honeys were: pH 3.8; moisture 17.3%; free acidity 20.4 mmol/kg; electrical conductivity 0.2 mS/cm; diastase activity 23.1 DN and HMF was below 3.8 mg/kg. Within the mineral content, potassium was quantitatively the most important mineral in the range of 125.79 to 1381.53 mg/kg followed by calcium of 20.37-63.65 mg/kg, magnesium 5.53-25.49 mg/kg and sodium 4.77- 19.44 mg/kg. The predominant sugar in honey samples was fructose having the mean value of 35.91 g/100 g followed by glucose 35.00 g/100 g. The disaccharide average content was 6.00 g/100 g. The melissopalynological analyzes showed that the most dominant pollens in honey samples were cruciferous (Cruciferae)-mainly rape (Brassica napus); rosacean (Rosaceae)-mainly raspberry (Rubus idaeus); white clover (Trifolium repens); sweet clover (Melilotus officinalis) and willow (Salix). The results of honey pollen profile analysis and calculated fructose/glucose ratios (0.89-1.17) both indicated to flower honeys. All of the analyzed honeys were found to meet European Legislation (EC Directive 2001/110) for all parameters.     

Palynological and physicochemical data characterisation of honeys produced in the Entre‐Douro e Minho region of Portugal

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 physicochemical properties may increase the commercial value of these products. The characteristics of thirty‐one honeys produced in the Entre‐Douro e Minho region in Portugal were studied. Pollen features and some physicochemical parameters (moisture, ash, pH, free acidity, electrical conductivity, hydroxymethylfurfural contain, apparent sucrose, reducing sugars and diastase activity) were determined. The samples were found to meet international honey specifications. The present study found a linear regression between the ash content of honeys and their specific conductivity. Five samples are listed as Eucalyptus honey, one sample as Citrus honey, and twenty‐five samples as multifloral honeys. Of the total, 87.1% exceeded the quality parameters and should be labelled as ‘virgin’ honey.     

PREDICTION OF HONEY SHELF LIFE

Fourteen commercial honey samples of different botanical origin (acacia, chestnut, citrus, eucalyptus, multifloral) were stored for up to 18 months at room temperature. Both 5-hydroxymethylfurfural (HMF) and diastase were evaluated and kinetics carried out. The highest HMF increase was in citrus and eucalyptus honeys at 3 mg/kg/month; the lowest in chestnut at 0.256 mg/kg/month. The highest diastase deactivation was in eucalyptus honey at 0.485 DU/kg/month; the lowest was in chestnut at 0.258 DU/kg/month. Honey shelf life was estimated for both indices, HMF and diastase, using a Bayesian approach. The results show that commercial honey shelf life depends on botanical origin as well as processing. Except chestnut, all other honeys showed shorter shelf lives than the declared one (usually 36 months). The shortest values, 15 months, were for citrus and eucalyptus honeys. The longest, 20 months, was for acacia and multifloral honeys.

PRACTICAL APPLICATIONS

Both kinetic equations and results of simulations can be used to estimate, for quality control purposes as well as regulation requirements, the most probable value of shelf life for a specific honey.     

A comparative study on phenolic profile,vitamin C content and antioxidant activity of Italian honeys of different botanical origin

The aim of our study was to identify and quantify the phenolic acids, flavonoids and vitamin C and to evaluate the antioxidant activity in ninety Italian honeys of different botanical origins (chestnut, sulla, eucalyptus, citrus and multifloral). The results showed that total phenolic and flavonoid contents varied from 11.08 to 14.26 mg GAE per 100 g honey and from 5.82 to 12.52 mg QE per 100 g honey, respectively. HPLC–UV analysis showed a similar but quantitatively different phenolic profile of the studied honeys. Vitamin C is present in all samples. Multifloral honey showed the highest amount of the detected total phenolic compounds and the highest vitamin C content. The DPPH value varied from 55.06 to 75.37%. Among the unifloral honeys, chestnut honey presented the highest levels of phenolic acids, flavonoids and vitamin C, which are closely associated with its high antioxidant activity. The results show that honey contains high amount of biologically active compounds, which play an important role in defining the nutraceutical quality of the product, and that the distribution of these compounds is influenced by the botanical origin.     

Determination of trace and minor elements in Slovenian honey by total reflection X-ray fluorescence spectroscopy

Trace and minor elements in Slovenian honey were analysed by total reflection X-ray fluorescence spectroscopy. Upto 16 elements (K, Cl, S, P, Ca, Mn, Rb, Cu, Fe, Ni, Cr, Br, Ti, Pb, Sr and As) were detected, in a range of average content from 1.24 mg kg⁻¹ for Sr to 2590 mg kg⁻¹ for K. Statistically significant differences were established between different types of honey (acacia, floral, lime, chestnut, spruce, fir, forest and Metcalfa pruinosa honeydew honey). The highest content of elements was determined in forest honey and the lowest in acacia honey. Honeys were also separated according to their botanical origin as nectar honey or honeydew honey. Total elemental content and the content of S, Cl, K and Rb in honeydew honey was statistically significantly higher than in nectar honey. Chestnut honey differed in statistically its significantly higher contents of Rb and Ca from nectar and honeydew honeys. The year of honey production proved to have no statistically significant influence on elemental content. A comparison of our data with the literature data showed a relatively large diversity.     

Mineral content and electrical conductivity of the honeys produced in Northwest Morocco and their contribution to the characterisation of unifloral honeys

In this study the mineral content, ash content and electrical conductivity of 98 honey samples from Northwest Morocco were studied. Using inductively coupled plasma atomic emission spectrometry (ICP‐AES), six minerals were identified and quantified: K, Mg, Mn, Cu, Fe and Zn. Potassium was the predominant mineral (accounting for 80% of the total minerals quantified), followed by Mg and Fe (9 and 3% respectively). The ash content values were lower than 0.6% in 95 of the samples. The higher electrical conductivity values corresponded to the honeydew honeys ( x = 1734 µS cm^?1). In addition, characterisation of the main unifloral honeys by principal component analysis (PCA), linear discriminant analysis (LDA) and multilayer perceptrons (MLP) was carried out. The PCA showed that the cumulative variance was approximately 67%. On the other hand, the LDA and MLP allowed perfect classification of the honeydew (100% correct classification) and Eucalyptus (92%) honeys. © 2003 Society of Chemical Industry     

Determination of the total phenolic,flavonoid and proline contents in Burkina Fasan honey,as well as their radical scavenging activity

Several honey samples (27) from Burkina Faso were analyzed to determine their total phenolic, flavonoid and proline contents as well as their radical scavenging activity. These samples consisted of 18 multifloral, 2 honeydew and 7 unifloral honeys, derived in the latter cases from flowers of Combretaceae, Vitellaria, Acacia and Lannea plant species. The total phenolic contents varied considerably with the highest values obtained for honeydew honey. Similarly, much variation was seen in total flavonoid and proline content, with Vitellaria honey having the highest proline content. Vitellaria honey was also found to have the highest antioxidant activity and content. The correlation between radical scavenging activity and proline content was higher than that for total phenolic compounds. This suggests that the amino acid content of honey should be considered more frequently when determining its antioxidant activity.     

Evaluation of antioxidant activity and total phenolics of selected Czech honeys

Honey serves as a good source of natural antioxidants, which are effective in reducing the risk occurrence of heart disease, cancer, cataracts, different inflammatory processes and immune-system decline. In the fresh selected Czech honey samples originated mainly from the region North Moravia antioxidant activity and total polyphenol content were determined. A total of 40 honey samples (multifloral, lime, rape, raspberry, mixture and honeydew honeys) native to different stations gained in the period from May by August year 2006 were analysed. Total phenolics (TP) content was determined by the modified Folin-Ciocalteau method [TP was expressed as mg of gallic acid equivalent (GA eq.) per kg of honey]. For evaluation of the antioxidant activity (AOA) three different methods were used, the ferric reducing antioxidant power (FRAP) assay, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and the 2,2′-azinobis(3-ethylbenzothiazolin)-6-sulfphonate (ABTS) assay. AOA was expressed in mg ascorbic acid equivalent (AA eq.) per kg of honey. The results indicated that TP and AOA in Czech honey varied greatly between the honey kinds, location and time of the harvest. Average TP ranged from 89.9 mg GA eq. kg^-1 in lime honey to 215.2 mg GA eq. kg⁻¹ in honeydew honey. Antioxidant activity determined by the DPPH, ABTS and FRAP methods was lowest in floral honeys. The highest values were obtained for honeydew and mixture honeys. ABTS and FRAP assays have been shown to be the optimal methods for AOA determination in honey. A positive linear correlation between AOA and TP was observed (in FRAP assay R² = 0.852). It indicates that phenolics are one of the main components responsible for antioxidant behaviour of honey. The obtained results support and extend complete knowledge about the content of bioactive phenolics and antioxidant activity in the Czech honeys.     

糖源蜜、花源蜜和市售蜂蜜品质的比较研究

该文对糖源蜜、花源蜜以及市售蜂蜜(黑蜂雪蜜、洋槐蜂蜜、天然蜂蜜、紫云英蜂蜜)的水分含量、电导率值、色度、果糖、葡萄糖、蔗糖、pH值、游离酸、总酸和蛋白质含量等基本理化成分以及矿物质含量、淀粉酶活性、总酚酸含量、总黄酮含量等活性成分进行测定.结果表明:糖源蜜、花源蜜以及市售4种蜂蜜的基本理化成分含量均符合我国国家标准,表...     

STUDIES ON LIBYAN HONEYS

Ten honey samples representing various floral types were obtained from different areas in Libya. Two other samples were obtained from hives, where bees were fed on sugar syrup and date syrup, respectively. The chemical composition and some characteristics of these samples were studied. The data obtained generally showed that the specifications of honeys produced in Libya conformed with those required for table honey. The application of thin-layer chromatography on cellulose-coated plates for the analysis of honey sugars yielded clear resolution and discrete spots. Some measures — such as high level of calcium, low level of potassium and UV-absorption spectra of honeys were suggested to be used for identifying the sugar-honeys and for ensuring the quality of blossom honeys. An attempt has been made to predict the granulation behavior of honeys and a derived regression formula was suggested.     

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.