Phenolic compounds and abscisic acid as potential markers for the floral origin of two Polish unifloral honeys

The phenolic profiles of Polish honey samples from heather (Calluna vulgaris L.) and buckwheat (Fagopyrum esculentum L.) were determined. The phenolic components were isolated from honey samples using Amberlite-XAD-2 as a solid-phase extraction sorbent. For the determination of the composition of the honey extracts HPLC with photodiode array detector was applied. Identification and quantification of phenolics was performed by comparison of their retention times and UV spectra with those of standard solutions of pure reference substances and by using those references as external standards. From among 20 commercially available standards over 15 of them were identified as present in all analysed samples. Taking into account the samples of the same unifloral honeys, similar qualitative but slightly quantitatively different phenolic characteristic profiles were observed. These profiles might be considered as “fingerprints” of heather and buckwheat honeys.     

HPLC flavonoid profiles as markers for the botanical origin of European unifloral honeys

The HPLC phenolic profiles of 52 selected unifloral honey samples produced in Europe were analysed to detect possible markers for the floral origin of the different honeys. Lime‐tree (five markers), chestnut (five markers), rapeseed (one marker), eucalyptus (six markers) and heather (three markers) honeys had specific markers with characteristic UV spectra. In addition, the flavanone hesperetin was confirmed as a marker for citrus honey, as well as kaempferol for rosemary honey and quercetin for sunflower honey. Abscisic acid, which had been reported to be a possible marker for heather honey, was also detected in rapeseed, lime‐tree and acacia honeys. Ellagic acid in heather honey and the hydroxycinnamates caffeic, p‐coumaric and ferulic acids in chestnut, sunflower, lavender and acacia honeys were also detected. The characteristic propolis‐derived flavonoids pinocembrin, pinobanksin and chrysin were present in most samples in variable amounts. © 2001 Society of Chemical Industry     

The determination of phenolic profiles of Serbian unifloral honeys using ultra-high-performance liquid chromatography/high resolution accurate mass spectrometry

Polyphenolic profiles of 44 unifloral Serbian honeys were analyzed using ultra-high-performance liquid chromatography (UHPLC) coupled with hybrid mass spectrometer which combines the Linear Trap Quadrupole (LTQ) and OrbiTrap mass analyzer. Rapid UHPLC method was developed in combination with a high sensitivity accurate mass scan and a simultaneous data dependent scan. The honey samples were of different botanical origin: acacia (Robinia pseudoacacia), sunflower (Helianthus annuus), linden (Tilia cordata), basil (Ocimum basilicum), buckwheat (Fagopyrum esculentum), oilseed rape (Brassica napus), and goldenrod (Solidago virgaurea). The presence of 43 compounds, mainly flavonoids, was proven in all honey samples by their characteristic mass spectra and fragmentation pattern. Relatively high amounts of chrysin, pinocembrin and galangin were identified in all honey extracts. p-Coumaric acid was not detected in basil, buckwheat and goldenrod honey extracts. A larger amount of gallic acid (max value 1.45 mg/kg) was found in the sunflower honey, while a larger amount of apigenin (0.97 mg/kg) was determined in the buckwheat honey in comparison with other honeys. The samples were classified according to the botanical origin using pattern recognition technique, Principal Component Analysis (PCA). The LTQ OrbiTrap technique was proven to be reliable for the unambiguous detection of phenolic acids, their derivatives, and flavonoid aglycones based on their molecular masses and fragmentation pattern.     

Phenolic profile,antioxidant activity and palynological analysis of stingless bee honey from Amazonas,Northern Brazil

In this study honey samples produced by Melipona (Michmelia) seminigra merrillae, collected in seven counties distributed in the central and southern region of Amazonas state in Brazil, were analysed for their botanical origin, content and profile of phenolic compounds, and antioxidant and antimicrobial activities. Twenty-two pollen types were identified. The total phenolic content ranged from 17 to 66 mg GAE/g of extract; the highest contents were found in honeys produced from pollen types such as Clidemia and Myrcia. The antioxidant activity was higher in the samples that contained higher quantities of phenolic compounds. In relation to the antibacterial activity, samples CAD3, CAD4 and SAD3 presented the best results. Fourteen phenolic compounds were determined. Among them, we identified the flavonoid taxifolin, which has not previously been described in honeys from stingless bees, and we report the identification of catechol in Brazilian honey samples for the first time.     

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.     

Antioxidant properties and phenolic content of sulla (Hedysarum spp.) honeys from Southern Italy

The geographical origin greatly influences the qualitative and nutraceutical characteristics of honey. In this study, a total of twenty‐four sulla honeys from eight different geographical areas of Southern Italy have been examined for total phenolic content (Folin–Ciocalteu method), antioxidant activity (FRAP and DPPH assays), colour intensity (ABS₄₅₀), and identification and quantification of phenolic acids (RP‐HPLC/UV‐VIS method). The total phenolic content ranged from 47.9 (Potentino honeys) to 248.3 mg GAE per kg honey (Penisola Sorrentina honeys). The antioxidant activity ranged from 47.06% (Basso Pollino honeys) to 88.25% (Penisola Sorrentina honeys), and from 98.26 μM Fe (II) (Potentino honeys) to 786.53 μm Fe (II) (Tarantino honeys) for DPPH and FRAP assays, respectively. Major phenolic acids identified in analysed samples were gallic, caffeic and ferulic acids. Correlations between the parameters analysed were statistically significant (P < 0.05). The results of the study showed that the parameters studied are greatly affected by the peculiarities of their production area.     

Determination of the geographical origin of Slovenian black locust,lime and chestnut honey

The geographical origin of three Slovenian unifloral honey types (black locust, lime and chestnut) was investigated by analysis of some physico-chemical parameters, the elemental content using total reflection X-ray fluorescence spectrometry (TXRF) and the stable carbon and nitrogen isotope ratios using isotope ratio mass spectrometry (IRMS). The results were interpreted by chemometric methods. A total of 122 samples of Slovenian black locust, lime and chestnut honeys were collected from domestic beekeepers all over Slovenia for three years. Slovenia is a small country by area, but paedologically and climatically diverse, therefore offering interesting possibilities for studying geographical influences. The combination of the investigated parameters offers the possibility of distinguishing among samples of specific honey types from the four different Slovenian natural-geographical macroregions, namely the Alpine, Dinaric, Pannonnian and Mediterranean regions. Lime honey samples were 100% correctly classified, while the success rates for black locust and chestnut honeys were slightly lower at 98.2% and 94.6%, respectively.     

Raw Millefiori honey is packed full of antioxidants

Total polyphenols, flavonoids and antioxidant power of raw honey samples from two of the most common Italian varieties, i.e., Millefiori and Acacia, were evaluated. Phenolic content, expressed as caffeic acid equivalents, ranged from 12.5 to 17.5 mg/100 g and from 3 to 11 mg/100 g in Millefiori and Acacia honeys, respectively. All Millefiori samples exhibited the highest flavonoid concentration being between 1.23 and 2.93 mg catechin equivalents (CE)/100 g honey. Total flavonoids in 100 g Acacia honeys were in the range of 0.45–1.01 mg CE. Acacia honeys had lower total antioxidant power, as assessed by ferric reducing/antioxidant power assay, than Millefiori. The relationship between phenolic content and antioxidant power was discussed. Comparative experimental analysis was performed with an artificial honey and processed honeys. Raw Millefiori honey is rich in both amount and variety of antioxidant substances, and its inclusion in the diet may be recommended to complement other polyphenol sources.     

Evaluation of the phenolic content,antioxidant activity and colour of Slovenian honey

Honey samples from the seven most common honey types in Slovenia were screened for total phenolic content by the modified Folin–Ciocalteu method, for potential antioxidant activity using the ferric reducing antioxidant power (FRAP) assay and by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method for antiradical activity. In addition the colour characteristics of honey samples were analysed. The results of the study showed that total phenolic content, antioxidant activity and colour parameters differ widely among different honey types. Phenolic content expressed as gallic acid equivalent ranged from 44.8 mg/kg in acacia honey to 241.4 mg/kg in fir honey. Antioxidant activity was the lowest in the brightest acacia and lime honeys and the highest in darker honeys, namely fir, spruce and forest. The colour of the Slovenian honeys, analysed in this study was very variable and ranged from pale yellow to dark brown. Correlations between the parameters analysed were found to be statistically significant (p < 0.05).     

Ling Heather Honey Authentication by Thixotropic Parameters

This paper assesses the actual reliability of four rheological parameters to help describe honeys that exhibit non-Newtonian behavior, being the most representative of which, ling heather (Calluna vulgaris (L.) Hull) honeys. Sampling included a representative number of unifloral ling heather honeys, non-unifloral honeys close to ling heather uniflorality, and other non-unifloral honeys containing ling heather. All experiments were performed at 25 °C and consisted on researching viscosity curves at different shear rates, as well as the time dependency of honey samples at a constant shear rate. Viscosity curves were correctly fitted by the Ostwald-de Waele model. Consistency coefficients (k) and flow behavior indexes (n) were calculated, and the Weltmann model was used to determine the stress decay behavior. The influence of honey moisture on k value was also researched. Hysteresis area and time-dependent thixotropic index B proved to be the most suitable parameters for a reliable ling heather honey authentication.     

Antioxidant capacity and vasodilatory properties of Mediterranean food: The case of Cannonau wine,myrtle berries liqueur and strawberry-tree honey

The aim of this work was to use different assays to evaluate the antioxidant and vasodilatory properties of three typical food products from the Mediterranean area and to correlate these activities with their phenolic content. For this purpose, red wines Cannonau, liqueurs obtained by cold maceration of myrtle (Myrtus communis L.) berries and bitter honeys obtained from strawberry-tree flowers (Arbutus unedo L.) were analysed. The total phenolic (TP) content was measured spectrophotometrically with a modified Folin–Ciocalteau method and phenolic compounds were identified and dosed by HPLC-DAD and LC-MS/MS. Antioxidant activities were evaluated with DPPH, FRAP and ABTS assays and the in vitro vasodilatory effects were assessed using norepinephrine precontracted rat aortic rings. Cannonau wines and myrtle liqueurs showed high levels of TP (1978 ± 279 and 1741 ± 150 mg GAE/L, respectively), linearly correlated to the results of FRAP, ABTS, and DPPH assays. Their maximal vasodilatory activity was 61.7 ± 4.1% and 53.0 ± 3.0%, respectively. Although strawberry-tree honey contained relatively high levels of phenolic compounds (922 ± 38 mg GAE/kg), it did not induce vasodilation, even at the highest dose tested (0.206 g/L). These results indicate that foods with high levels of phenolic compounds should be studied using several different biological assays before being recommended to the general public as functional foods.     

HPTLC Phenolic Profiles as Useful Tools for the Authentication of Honey

The present study reveals the utility of high-performance thin-layer chromatographic (HPTLC) fingerprinting of phenolic constituents for the authentication of monofloral honeys. The obtained data enables a more complete assessment of honey quality and the identification of emerging threats to honey quality. The developed procedure facilitates differentiation of varietal honeys and detection of honey adulterations. We used an HPTLC fingerprint analysis to determine the characteristic patterns of different honey types (willow, buckwheat, heather, pine honeydew, and manuka honey). The HPTLC chromatograms were used to determine the differences in the botanical origin of the honey samples on the basis of the band profiles, which are characteristic for each honey type. Identification of 11 polyphenols was performed by comparison of the color and R_f of the bands with available standards. Additionally, the results were confirmed by an HPLC analysis.     

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.     

Determination of some individual phenolic compounds and antioxidant capacity of mead produced from different types of honey

The aim of this study was to promote mead (honey wine) production by testing the appropriateness of different honey varieties which were obtained from the flora of Turkey for the production of mead. Cotton‐Mezda (Gossypium spp.), pine (Pinus spp.) and flower honeys were used in the fermentation studies. Pure culture Saccharomyces cerevisiae yeasts were used in the mead studies. While determining the phenolic contents of meads via HPLC method, five phenolic acids and two flavonoids were used as standards with known antioxidant properties. In addition, total antioxidant activity was analysed in meads using trolox equivalent antioxidant capacity (TEAC). Among the phenolic acids, the most abundant one was protocatechuic acid (75.12–179.03 μg/L) and among flavonoids it was catechin (10.38–125.55 μg/L). It was found out that total phenolic content ranged from 103.56 GAE to 167.89 GAE mg/L. Copyright © 2017 The Institute of Brewing & Distilling     

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.     

Phenolic content,antioxidant and physico‐chemical properties of Sardinian monofloral honeys

In this study, fifty‐one monofloral Sardinian honeys from ten various floral origins were screened for their phenolic content, antioxidant activity, colour and electrical conductivity. The total phenolic amounts have been evaluated by Folin–Ciocalteu method, whereas quantification of several phenolic compounds (phenolic acids and flavonoids) has been carried out by HPLC‐DAD technique. The richest sample in phenolic compounds resulted strawberry tree honey with about 40 mg GAE/100 g, as well FRAP test and DPPH˙ test confirm that antioxidant activity of strawberry tree honey extract exceed both honey extracts and synthetic antioxidants like BHA and BHT. Among the studied phenolic compounds a total of five phenolic acids (ferulic, syringic, trans‐cinnamic, chlorogenic and p‐hydroxycinnamic) and nine flavonoids (catechin, kaempferol, rutin, quercetin, luteolin, apigenin, galangin, pinocembrin and pinobanksin) were identified. Our results show good correlations between total polyphenol amount and antioxidant activity and between colour and electrical conductivity.     

Phenolic compounds and methylglyoxal in some New Zealand manuka and kanuka honeys

The principal phenolic compounds and methylglyoxal were analysed in New Zealand Leptospermum scoparium (manuka) and Kunzea ericoides (kanuka) honeys. These honeys shared six phenolic acids as primary components and differentiation was possible as relative proportions varied. Manuka honey contained an elevated concentration of a trimethoxybenzoic acid and methylglyoxal; and 2-methoxybenzoic acid and methylglyoxal concentrations were linearly correlated in fresh manuka honey. Kanuka honey contained an elevated concentration of methoxyphenyllactic acid. The concentration of the phenolic components increased with maturation in both honey types; and this profile development, along with a corresponding increase of methylglyoxal concentration, was linear in manuka honey. Nectar analysed from the plant species contained the same phenolic components as the honeys. These results demonstrated the phenolic profile could be used to differentiate the honey types, heat treatment of honey could be identified, and the presence of these components may contribute to the efficacy of these honeys in therapeutic uses.     

Phenolic acids in Australian Melaleuca,Guioa, Lophostemon,Banksia and Helianthus honeys and their potential for floral authentication

Eight phenolic acids and two abscisic acid isomers in Australian honeys from five botanical species (Melaleuca, Guioa, Lophostemon, Banksia and Helianthus) have been analyzed in relation to their botanical origins. Total phenolic acids present in these honeys range from 2.13 mg/100 g sunflower (Helianthus annuus) honey to 12.11 mg/100 g tea tree (Melaleuca quinquenervia) honey, with amounts of individual acids being various. Tea tree honey shows a phenolic profile of gallic, ellagic, chlorogenic and coumaric acids, which is similar to the phenolic profile of an Australian Eucalyptus honey (bloodwood or Eucalyptus intermedia honey). The main difference between tea tree and bloodwood honeys is the contribution of chlorogenic acid to their total phenolic profiles. In Australian crow ash (Guioa semiglauca) honey, a characteristic phenolic profile mainly consisting of gallic acid and abscisic acid could be used as the floral marker. In brush box (Lophostemon conferta) honey, the phenolic profile, comprising mainly gallic acid and ellagic acid, could be used to differentiate this honey not only from the other Australian non-Eucalyptus honeys but also from a Eucalyptus honey (yellow box or Eucalyptus melliodora honey). However, this Eucalyptus honey could not be differentiated from brush box honey based only on their flavonoid profiles. Similarly, the phenolic profile of heath (Banksia ericifolia) honey, comprising mainly gallic acid, an unknown phenolic acid (Ph1) and coumaric acid, could also be used to differentiate this honey from tea tree and bloodwood honeys, which have similar flavonoid profiles. Coumaric acid is a principal phenolic acid in Australian sunflower honey and it could thus be used together with gallic acid for the authentication. These results show that the HPLC analysis of phenolic acids and abscisic acids in Australian floral honeys could assist the differentiation and authentication of the honeys.     

Carbohydrate composition of Spanish unifloral honeys

As part of a research project aiming to characterise the most important Spanish floral honeys, the carbohydrate analysis of 109 honey samples was carried out. The main unifloral sources, identified by pollen analysis, were Citrus, heather, Eucalyptus, rosemary, Echium and Rosaceae. A high proportion of multifloral samples were also present.     

Flavonoid pattern of sage (Salvia officinalis L.) unifloral honey

The aim of the present paper was to determine the flavonoids in monofloral sage (Salvia officinalis L.) honey which is characteristic and specific for the area of Croatian coast and islands. For that purpose 38 sage honey samples from two production seasons were analysed. After specific pollen content determination, and analyses of selected physicochemical parameters which confirmed that samples are in compliance with national and international regulations and can be regarded as unifloral sage honeys, flavonoid fraction was isolated and analysed using RP-HPLC/DAD method. The HPLC analysis showed that all examined sage honey samples contain quercetin (3,3′,4′,5,7-pentahydroxyflavone), luteolin (3′,4′,5,7-tetrahydroxyflavone), kaempferol (3,4′,5,7-tetrahydroxyflavone), apigenin (4′,5,7-trihydroxyflavone), chrysin (5,7-dihydroxyflavone) and galangin (3,5,7-trihydroxyflavone), as well as p-coumaric (trans-4-hydroxycinnamic acid) and caffeic acid (3,4-dihydroxycinnamic acid). Total amount of identified flavonoids varied from 109.4 μg/100 g of honey to 589.9 μg/100 g of honey, with the average of 288.5 μg/100 g of honey. All analysed honey samples showed common and specific flavonoid profile which could be the basis for differentiating sage from other monofloral honeys.