Geographical discrimination of pine and fir honeys using multivariate analyses of major and minor honey components identified by 1H NMR and HPLC along with physicochemical data

Analytical insights for ensuring authenticity of Greek agriculture products: Unveiling chemical marker applications

Food authentication, including the differentiation of geographical or botanical origin, the method of production i.e. organic vs. conventional farming as well as the detection of food fraud/adulteration, has been a rapidly growing field over the past two decades due to increasing public awareness regarding food quality and safety, nutrition, and health. Concerned parties include consumers, producers, and legislators. Thus, the development of rapid, accurate, sensitive, and reproducible analytical methods to guarantee the authenticity of foods is of primary interest to scientists and technologists. The aim of the present article is to summarize research work carried out on the authentication of Greek agricultural products using spectroscopic (NIR, FTIR, UV-Vis, Raman and fluorescence spectroscopy, NMR, IRMS, ICP-OES, ICP-MS) and chromatographic (GC, GC/MS, HPLC, HPLC/MS, etc.) methods of analysis in combination with chemometrics highlighting the chemical markers that enable product authentication. The review identified a large number of chemical markers including volatiles, phenolic substances, natural pigments, elements, isotopes, etc. which can be used for (i) the differentiation of botanical/geographical origin; conventional from organic farming; production procedure and vintage year, etc. and (ii) detection of adulteration of high quality plant and animal origin foods with lower value substitutes. Finally, the constant development of reliable analytical techniques in combination with law enforcement authorities will ensure authentic foods in terms of quality and safety for consumers.

Impact of floral and geographical origins on honey quality parameters in Saudi Arabian regions

This article examined the effect of geographical (different climate conditions) and floral origins on some quality parameters of honey including the activity of diastase enzyme. Moreover, some non-quality parameters were investigated such as the pH, fructose, glucose, ratio of fructose/glucose and invertase. The honey samples were collected from Asir (cold climate) and Jazan (hot climate) regions at the southwestern part of Saudi Arabia. The geographical origin significantly affected the mean value moisture of the Acacia honey (p-value = 0.02), conductivity of the polyfloral honey (p-value = 0.03), sucrose of the Acacia honey (p-value = 0.02), diastase activity of the Acacia (p-value = 0.001), Ziziphus (p-value = 0.046) and polyfloral honey (p-value ≤ 0.001), fructose of the Acacia honey (p-value = 0.01), glucose of the Ziziphus honey (p-value = 0.03), fructose/ glucose ratio of the Ziziphus honey (p-value = 0.035), and invertase activity of the polyfloral honey (p-value ≤ 0.001). Regarding the effect of the floral origin of the honey from Asir region, the sucrose percentage of the Acacia honey was significantly more than that of the polyfloral honey (p- value = 0.003), the diastase activity of the Acacia honey was significantly more than its activity in the Ziziphus honey (p- value = 0.044), glucose percentage of the Ziziphus honey was significantly more the glucose percentage of the Acacia honey (p-value = 0.009) and the fructose/ glucose ratio of the Ziziphus honey was significantly more than that of the Acacia and polyforal honeys (p-value = 0.011 and p-value = 0.045, respectively). Concerning the significant effects of the floral origin on the quality parameters of the honey samples from Jazan region, the moisture of the Ziziphus honey was significantly increased when compared to the moisture of the Acacia honey (p-value = 0.038), the acidity of the polfloral honey was significantly more than the acidity of the Acacia honey (p-value = 0.049), the sum of fructose and glucose of the polyfloral honey was significantly increased compared to that of the Acacia honey (p-value = 0.015), the pH of the Ziziphus hiney was significantly more than the pH of the polyfloral honey (0.011) and the fructose of the polfloral honey was significantly more than that of the Acacia honey (p-value = 0.031). The effect of the geographical origin of the honey samples on their quality parameters depends on their floral origin and the effect of their floral origin differs according to their geographical origin. This article suggests considering collectively the geographical and floral origins effect when developing honey standards. However, the Codex standards for honey started considering this issue when it changed the standard concentration of HMF in honey from not more than 80-40 mg/Kg for honeys from cold climate and 80 mg/Kg for honeys from hot climates.

Analysis of Free Amino Acid Composition and Honey Plant Species in Seven Honey Species in China

Honey is well-known as a food product that is rich in active ingredients and is very popular among consumers. Free amino acids (FAAs) are one of the important nutritional components of honey, which can be used not only as a nutritional indicator of honey but also as an indicator of plant source identification. In this study, the contents of 20 FAAs in seven types of honey from 11 provinces in China were examined for the first time. The 20 FAAs were analyzed by ultra-performance liquid chromatography-mass spectrometry/mass spectrometry (UPLC-MS/MS). By analyzing 93 honey samples from seven types of honey, the FAAs were found to range from 394.4 mg/kg (linden honey) to 1771.7 mg/kg (chaste honey). Proline ranged from 274.55 to 572.48 mg/kg, and methionine was only present in some of the linden honey, chaste honey, acacia honey, and rape honey. Evaluated by amino acid principal component analysis, multifloral grassland honey had the highest overall evaluation score, acacia and jujube honey were the most similar, while chaste honey was the least similar to the other types of honey. In addition, DNA was extracted from 174 Xinjiang grassland honey samples and different plant leaves for PCR and sequencing to identify the species of nectar plants. As a result, 12 families and 25 species of honey plants were identified. The results confirmed the diversity of FAAs in dissimilar types and sources of honey. This study provides a reference for expanding honey quality standards and verifying the authenticity of honey.

Quality of Honey Imported into the United Arab Emirates

This study was performed to assess the physicochemical quality characteristics of honey imported by the United Arab Emirates (UAE) via Dubai ports between 2017 and 2021. There were 1330 samples analyzed for sugar components, moisture, hydroxymethylfurfural (HMF) content, free acidity, and diastase number. Of the honey tested, 1054 samples complied with the Emirates honey standard, but 276 (20.8%) did not; this was due to non-compliance with one or more quality parameters, thus suggesting some level of adulteration, improper storage or inappropriate heat treatment. For the non-compliant samples, the average values of sucrose content ranged from 5.1 to 33.4%; the sum of glucose and fructose ranged from 19.6 to 88.1%; the moisture content varied from 17.2 to 24.6%; the HMF occurred in a range from 83.2 to 663.0 mg/kg, and the acidity varied from 52 to 85 meq/kg. The non-compliant honey samples were grouped according to their country of origin. India was shown to be the country having the highest percentage of non-compliant samples at 32.5% and Germany had the lowest at 4.5%. This study emphasized that the inspection of honey samples traded internationally should involve physicochemical analysis. A comprehensive inspection of honey at the Dubai ports should reduce incidents of adulterated products being imported.

Insight into the Recent Application of Chemometrics in Quality Analysis and Characterization of Bee Honey during Processing and Storage

The application of chemometrics, a widely used science in food studies (and not only food studies) has begun to increase in importance with chemometrics being a very powerful tool in analyzing large numbers of results. In the case of honey, chemometrics is usually used for assessing honey authenticity and quality control, combined with well-established analytical methods. Research related to investigation of the quality changes in honey due to modifications after processing and storage is rare, with a visibly increasing tendency in the last decade (and concentrated on investigating novel methods to preserve the honey quality, such as ultrasound or high-pressure treatment). This review presents the evolution in the last few years in using chemometrics in analyzing honey quality during processing and storage. The advantages of using chemometrics in assessing honey quality during storage and processing are presented, together with the main characteristics of some well-known chemometric methods. Chemometrics prove to be a successful tool to differentiate honey samples based on changes of characteristics during storage and processing.

¹H-NMR Metabolic Profiling, Antioxidant Activity, and Docking Study of Common Medicinal Plant-Derived Honey

The purpose of this investigation was to determine ¹H-NMR profiling and antioxidant activity of the most common types of honey, namely, citrus honey (HC1) (Morcott tangerine L. and Jaffa orange L.), marjoram honey (HM1) (Origanum majorana L.), and clover honey (HT1) (Trifolium alexandrinum L.), compared to their secondary metabolites (HC2, HM2, HT2, respectively). By using a ¹H-NMR-based metabolomic technique, PCA, and PLS-DA multivariate analysis, we found that HC2, HM2, HC1, and HM1 were clustered together. However, HT1 and HT2 were quite far from these and each other. This indicated that HC1, HM1, HC2, and HM2 have similar chemical compositions, while HT1 and HT2 were unique in their chemical profiles. Antioxidation potentials were determined colorimetrically for scavenging activities against DPPH, ABTS, ORAC, 5-LOX, and metal chelating activity in all honey extract samples and their secondary metabolites. Our results revealed that HC2 and HM2 possessed more antioxidant activities than HT2 in vitro. HC2 demonstrated the highest antioxidant effect in all assays, followed by HM2 (DPPH assay: IC₅₀ 2.91, 10.7 μg/mL; ABTS assay: 431.2, 210.24 at 50 ug/mL Trolox equivalent; ORAC assay: 259.5, 234.8 at 50 ug/mL Trolox equivalent; 5-LOX screening assay/IC₅₀: 2.293, 6.136 ug/mL; and metal chelating activity at 50 ug/mL: 73.34526%, 63.75881% inhibition). We suggest that the presence of some secondary metabolites in HC and HM, such as hesperetin, linalool, and caffeic acid, increased the antioxidant activity in citrus and marjoram compared to clover honey.

Analysis of 18 Free Amino Acids in Honeybee and Bumblebee Honey from Eastern and Northern Europe and Central Asia Using HPLC-ESI-TQ-MS/MS Approach Bypassing Derivatization Step

The profile of amino acids and mono- and disaccharides in conventional polyfloral honey originated from Latvia and Tajikistan and less found in nature bumblebee honey from Russia was investigated. The analysis of free amino acids (FAAs) accomplished by multiple reaction monitoring (MRM) using triple quadrupole mass selective detection (HPLC-ESI-TQ-MS/MS) revealed the presence of 17 FAAs. The concentration of FAAs varied in the range of 0.02–44.41 mg 100 g−1 FW. Proline was the main representative of FAAs, contributing to the total amount of FAAs from 41.7% to 80.52%. The highest concentration of proline was found in bumblebee and buckwheat honey, corresponding to 44.41 and 41.02 mg 100 g−1, respectively. The concentration of essential amino acids (AAs), i.e., leucine, and isoleucine was found to be the highest in buckwheat honey contributing up to 12.5% to the total amount of FAAs. While, the concentration of branched-chain AAs fluctuated within the range of 1.08–31.13 mg 100 g−1 FW, with buckwheat honey having the highest content and polyfloral honey the lowest, respectively. The results of this study confirmed the abundance of FAAs both in honeybee and bumblebee honey. However, the concentration of individual FAAs, such as proline, aspartic acid, leucine, and isoleucine in bumblebee honey was many folds higher than observed in honeybee polyfloral honey.

Chemical Profile, Antioxidant and Enzyme Inhibition Activities of Natural Saudi Sidr and Talh Honeys

Honey is used since ancient time as a food and to cure many diseases. The present study investigated the chemical constituents, antioxidant and enzyme inhibition activities of natural Saudi Sidr (SH) and Talh (TH) honeys. Beside entire honey samples, ethyl acetate, ethanol and water extracts were prepared. The total polyphenolic content of SH, TH and their extracts was in the range of 2.86-7.21 and 3.80-17.33 mg gallic acid equivalents/g, respectively and the total flavonoids content was in the range of 0.05-1.17 and 0.18-2.38 mg rutin equivalents/g, respectively. Out of the 53 standards analyzed by HPLC, 27 compounds were detected with highest number of compounds identified in the ethyl acetate extract of TH (45 %, 24/53) and SH (26 %, 14/53), respectively. Quinic acid was dominant compound identified in all honey samples with the highest content determined in TH ethanol extract (4454 μg/g). The majority of tested samples possessed considerable anti-radicals and reducing ions capacity with the ethyl acetate extract from TH exerted significantly (p<0.05) the highest activity. All honey samples did not show chelating iron metal property. Honey samples revealed variable enzyme inhibition activity with TH (entire and/or ethyl acetate extract) showed significantly (p<0.05) the highest acetylcholinesterase, butyrylcholinesterase, tyrosinase and α-amylase inhibition activity. In conclusion, ethyl acetate is the best solvent for extraction of bioactive molecules from the two honey types. Moreover, the dark-colored TH contained the highest number of molecules and consequently exerted the best antioxidant and enzyme inhibition activities in most assays.

An attempt to classify the botanical origin of honey using visible spectroscopy

BACKGROUND

The production of honey, and especially the unifloral varieties, is limited by factors such as weather conditions or the availability of nectar flow and honeydew. This results in a deficit in supply leading to the adulteration of honey. If they are not properly labeled, customers cannot distinguish artificial / synthetic products from real honey. Currently, the basic, commonly used method for determining the varieties of honey (botanical origin) is palynological analysis. However, this procedure is quite difficult owing to the dearth of experienced staff in the field of melissopalynology.

RESULTS

A method for identifying and classifying natural honey accurately based on its botanical origin has therefore been proposed. This analysis would rely on the visible light spectra transmitted through a relatively thin layer of the substance of interest, regardless of deviations in thickness. We present algorithms for analyzing the transmittance spectra-parametrization based on polynomial approximation (PMA) and applying a method for spectra selection and reduction (SSR) and a classical classification model (decision tree). A comparison is presented of the classification of four varieties of honey, confirmed by pollen analysis, obtained from the analysis of optically measured transmittance spectra of the samples. The algorithms that are compared contain a decision tree that uses raw data, data reduced by principal component analysis (PCA), and data after calculations based on the proposed algorithms alone (PMA and SSR) and together with the PCA method.

CONCLUSION

This novel method produced outstanding results in comparison with the standard PCA method and is helpful in identifying the botanical origin of honey effectively. © 2021 Society of Chemical Industry.

Current status of the gastrointestinal digestion effects on honey: A comprehensive review

In the past five years, more than 8000 scientific reports have been published on honey composition and its potential bioactivity as a source of pro-health components. However, the potential effectiveness of nutrients and other compounds in the human body is greatly influenced by the individual digestion conditions. Consequently, changes in the structure of honey components and their interactions with other constituents are expected and they may affect the bioaccessibility, the bioavailability, and further physiological functions of honey nutrients and bioactives. In this context, in addition to present key physiological characteristics for each step of the human digestion and their simulation aspects, this review also summarizes and discusses available data regarding the effect of the digestion (in vitro and in vivo) on honey compounds. Additionally, we consider the influence of the digestion on biological activities described for the compounds in the honey.

Suitability of sugar, amino acid, and inorganic ion compositions to distinguish fir and spruce honey

Honeydew honey is produced by bees from excretions of plant-feeding insects, such as aphids and scale insects. Honeydew on conifers, like fir (Abies alba) or spruce (Picea abies), is produced by different species of the genera Cinara and Physokermes. This means that honeydew honey can stem from different botanical as well as zoological origins, but so far it is not possible to clearly distinguish the different types of honeys. In the attempt to identify distinguishing markers, 19 sugars, 25 amino acids and 9 inorganic ions were quantified in three groups of honeydew honey (fir/Cinara, spruce/Cinara and spruce/Physokermes) with 20 honey samples each. It could be demonstrated that the contents of isomaltose, raffinose, erlose, two undefined oligosaccharides, several amino acids, sulfate, and phosphate differed significantly between the three groups of honey. Furthermore, multivariate analyses resulted in a separation of spruce/Physokermes honey from spruce- or fir/Cinara honey due to its higher contents of phosphate, sulfate, erlose and two undefined oligosaccharides. Moreover, the amino acid composition and the isomaltose as well as the raffinose contents proved useful in the distinction between fir/Cinara and spruce/Cinara honey. In sum, the contents of sugars, amino acids, and inorganic ions in German fir and spruce honeys provide useful information about the botanical and zoological origin of honeydew honeys.

Classification of the botanical and geographical origins of Chinese honey based on 1H NMR profile with chemometrics

In this paper, we report a newly developed non-target ¹H NMR detection associated with chemometrics method to classify the botanical and geographical origins of the monofloral Chinese honey. ¹H NMR tests of 218 monofloral honey samples of 8 classes (Acacia, Jujube, Linden, Longan, Orange, Rape, Sunflower, Vitex) collected in 2017-2019 across China were conducted under the optimal sample preparation conditions and NMR acquisition parameters. The whole profiles of NMR spectra instead of individual or partial signals from specific components were processed and extracted, then fed to SIMCA-P to classify the botanical and geographical origins through non-target statistical analysis. For the botanical origins, most of them could be classified clearly according to Principal Component Analysis (PCA) with both R² and Q² close to 1. Orthogonal Partial Least Squares Discrimination Analysis (OPLS-DA) model could classify the honey floral types successfully with R²Y and Q² greater than 0.85. It is found that the integral bin for data extraction has no obvious influence on the classification. For the geographical origins, the classification at different geographical levels (providence and town) could be successfully distinguished by OPLS-DA model. The promising preliminary results with the geographical classification at 40 km level unambiguously demonstrate the application of this NMR-based multi-species non-targeted method for the honey authenticity. Successful result is obtained on a pilot prediction of the geographical classification. Comparing with the methods based on other techniques, the advantages of this reported one are less sample amount needed, simple preparation, short test time, and non-targeted multi-species detection.

NMR carbohydrate profile in tracing acacia honey authenticity

The sugar profile in honey can be used as a fingerprint to confirm the authenticity or reveal the adulteration of the product by sweetener addition. In this work, we have accurately determined the profile of 20 minor saccharides in a set of 46 European acacia honeys using a recently proposed NMR approach based on the CSSF-TOCSY experiment. Comparison of this reference profile with the sugar composition of several Chinese honey samples of the same declared botanical origin has revealed important differences. A detailed analysis of the saccharide profile of these Chinese honeys suggests product adulteration by overfeeding bee colonies with industrial sugars syrups during the main nectar flow period.

The potentiality of NMR-based metabolomics in food science and food authentication assessment

In the last years, there was an increasing interest on nuclear magnetic resonance (NMR) spectroscopy, whose applications experienced an exponential growth in several research fields, particularly in food science. NMR was initially developed as the elective technique for structure elucidation of single molecules and nowadays is playing a dominant role in complex mixtures investigations. In the era of the "omics" techniques, NMR was rapidly enrolled as one of the most powerful methods to approach metabolomics studies. Its use in analytical routines, characterized by rapid and reproducible measurements, would provide the identification of a wide range of chemical compounds simultaneously, disclosing sophisticated frauds or addressing the geographical origin, as well as revealing potential markers for other authentication purposes. The great economic value of high-quality or guaranteed foods demands highly detailed characterization to protect both consumers and producers from frauds. The present scenario suggests metabolomics as the privileged approach of modern analytical studies for the next decades. The large potentiality of high-resolution NMR techniques is here presented through specific applications and using different approaches focused on the authentication process of some foods, like tomato paste, saffron, honey, roasted coffee, and balsamic and traditional balsamic vinegar of Modena, with a particular focus on geographical origin characterization, ageing determination, and fraud detection.

Two-Way Characterization of Beekeepers' Honey According to Botanical Origin on the Basis of Mineral Content Analysis Using ICP-OES Implemented with Multiple Chemometric Tools

Asfaka, fir, flower, forest flowers and orange blossom honeys harvested in the wider area of Hellas by professional beekeepers, were subjected to mineral content analysis using inductively coupled plasma optical emission spectrometry (ICP-OES). The main purpose of this study was to characterize the mineral profile and content of toxic metals such as lead, cadmium and chromium, and investigate whether specific minerals could assist accurately in the botanical origin discrimination with implementation of chemometrics. Twenty-five minerals were identified (Ag, Al, As, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Se, Si, Ti, Tl, V, Zn) and quantified. Results showed that the mineral content varied significantly (p < 0.05) according to honey botanical origin, whereas lead, cadmium, and chromium contents ranged between 0.05–0.33 mg kg⁻¹, <0.05 mg kg⁻¹, and in the range of <0.12 to 0.39 mg kg⁻¹, respectively. Fir honeys from Aitoloakarnania region showed the highest mineral content (182.13 ± 71.34 mg kg⁻¹), while flower honeys from Samos Island recorded the highest silicon content (16.08 ± 2.94 mg kg⁻¹). Implementation of multivariate analysis of variance (MANOVA), factor analysis (FA), linear discriminant analysis (LDA), and stepwise discriminant analysis (SDA) led to the perfect classification (100%) of these honeys according to botanical origin with the use of Al, As, Ca, Mg, Mn, Ni, Pb, Sb, Si, Zn and total mineral content. However, the higher lead content in the majority of samples than the regulated upper limit (0.10 mg kg⁻¹), sets the need for further improvements of the beekeepers’ practices/strategies for honey production.

Physicochemical Properties and Pollen Profile of Oak Honeydew and Evergreen Oak Honeydew Honeys from Spain: A Comparative Study

This work investigates the similarities and differences of oak honeydew (Quercus pyrenaica Willd.) and evergreen honeydew (Quercus ilex L.) honey produced in Spain. For this purpose, the physicochemical characteristics of 17 samples from oak honeydew and 11 samples from evergreen honeydew collected in different geographical regions were analyzed. All the samples accomplished European Union requirements for honey consumption. Both honey types had amber dark color; however, the evergreen oak honey was clearer than oak honey, having higher mean values in a* and b* coordinates of CIELab scale. In general, both honey types exhibited high electrical conductivity, a moderate value of pH, medium to low water content, and high diastase activity. The reducing sugar content was significantly lower and maltose content was significantly higher in evergreen honeydew. In addition, total phenols and total flavonoid contents, the antioxidant activity and the melissopalynological analysis was performed. The oak honeydew honey had a higher abundance of Castanea, Rubus and Erica pollen grains, while the evergreen oak honeydew honey had a higher abundance of Lavandula, Olea europaea or Anthyllis cytisoides. A multivariate analysis using the most representative pollen types and physicochemical components facilitated the differentiation of the honey samples, thus this information can be useful for the honey characterization.

An overview of physicochemical characteristics and health-promoting properties of honeydew honey

Honeydew honey has differentiated chemical and physicochemical characteristics besides potential functional properties such as antimicrobial, anti-inflammatory and antioxidant. In this sense, the interest and consumption of this honey as a functional product by the food industry and consumers have increased. Honeydew honeys usually present dark color, a lower content of monosaccharides and higher values of pH, acidity, electric conductivity, proteins, minerals, phenolic compounds, and oligosaccharides compared to blossom honeys, which contribute to its outstanding biological activities. Consequently, contaminations and adulterations of this honey can occur and compromise the quality, safety and authenticity of honeydew honey. Thus, detailed knowledge of the composition and properties of honeydew honeys is of great importance, especially considering that honeydew honeys are still few studied and therefore underestimated. Therefore, in this review, the physicochemical characteristics, chemical and bioactive composition, functional and health-promoting properties of honeydew honey as well as contamination, adulteration and authenticity of this honey are summarized.

Characterization of Sicilian Honeys Pollen Profiles Using a Commercial E-Tongue and Melissopalynological Analysis for Rapid Screening: A Pilot Study

Honey is usually classified as "unifloral" or "multifloral", depending on whether a dominating pollen grain, originating from only one particular plant, or no dominant pollen type in the sample is found. Unifloral honeys are usually more expensive and appreciated than multifloral honeys, which highlights the importance of honey authenticity. Melissopalynological analysis is used to identify the botanical origin of honey, counting down the number of pollens grains of a honey sample, and calculating the respective percentages of the nectariferous pollens. In addition, sensory properties are also very important for honey characterization, and electronic senses emerged as useful tools for honey authentication. In this work, a comparison of the results obtained from melissopalynological analysis with those provided by a potentiometric electronic tongue is given, resulting in a 100% match between the two techniques.