HMF and diastase activity in honeys: A fully validated approach and a chemometric analysis for identification of honey freshness and adulteration

Authenticity of Greek honey based on phenolic compounds and physicochemical characteristics

The main technique for classifying honey according to its botanical origin is melissopalynology, using pollen analysis. However, there is an issue where beekeepers collect pollen at the entrance to the hive or pollen is added to the honey after it is harvested with the aim of deceiving consumers. In the current work, the potential to authenticate Greek honeys based on their phenolic profile and some of their physicochemical characteristics, such as electrical conductivity, HMF content, and diastase activity, since they are the main quality parameters of honey, was studied. Initially, 95 honey samples from 11 botanical sources were collected from different places in Greece. Pollen analysis was performed to classify the honeys into individual species, and then HMF content, diastase activity, electrical conductivity values, total phenolic content, and 23 individual phenolic compounds were determined. An authenticity study was carried out using ANOVA and MANOVA, and PCA, LDA, OPLS-DA as well as logistic regression. It was found that the phenolic compound chlorogenic acid can be used as a marker for Greek chestnut honey, homogentisic acid and 2-cis,4-trans-abscisic acid can be used as markers for Greek Arbutus honey and the combination of gallic acid and protocatechuic acid can be used as markers for Greek oak honeydew honey, and are proposed as alternative or complementary ways of ensuring the authenticity of Greek honey.

Physicochemical Characteristics, Antioxidant Capacity, and Antimicrobial Activity of Stingless Bee Honey from Malaysia: Heterotrigona itama, Lophotrigona canifrons, and Tetrigona binghami

The composition and bioactivity of honey are influenced by its botanical, geographical, and entomological origins. This study investigates the physicochemical characteristics, antioxidant capacity, and antimicrobial activity of stingless bee honey (SBH) produced by three Malaysian stingless bee species: Heterotrigona itama, Lophotrigona canifrons, and Tetrigona binghami. The moisture content ranges from 25.44% to 40.36%, while the honey color varies from light amber to dark amber. The fructose, glucose, and sucrose contents range from 5.45 to 16.91 g/100 g, 3.85 to 19.64 g/100 g, and undetectable to 2.47 g/100 g, respectively. Trehalulose is present at a level of 15.42 to 43.75 g/100 g, with L. canifrons honey exhibiting the highest trehalulose concentration. All samples show low 5-HMF content and no detectable diastase activity. T. binghami honey has the lowest pH, highest electricity conductivity and acidity, and exhibits the strongest antimicrobial activity against Staphylococcus aureus and Escherichia coli. H. itama honey exhibits the highest antioxidant potential based on ABTS, FRAP, and DPPH assays. Among the three species, L. canifrons honey contains the highest total phenolic content. These findings provide valuable insights into the unique properties of SBH, supporting further research, quality assessment, and the development of international standards.

Bacillus subtilis Contributes to Amylase Production in the Honey Sac of Apis mellifera

BACKGROUND

Amylase activity is a critical biomarker for assessing the freshness of honey. Historically, bees have been considered the sole source of honey amylase. However, recent studies suggest that Bacillus subtilis may also contribute to amylase production in the honey sac of Apis mellifera.

METHODS

In this study, amylase levels were measured in samples of nectar, honey sac fluid, and honey. The identification of B. subtilis in nectar, honey sac, and honey was evaluated. An in vitro bacterial culture system and a feeding experiment were developed to simulate honey sac conditions.

RESULTS

Our results showed that B. subtilis was detected in all sample groups, with the highest concentration in honey sac samples. Amylase levels in honey sac and honey samples were significantly higher than those in nectar. In the simulation experiment, amylase activity was only observed in cultures containing both B. subtilis and sucrose/nectar; no activity was detected in cultures containing only H2O or no B. subtilis. In the feeding experiment, bees fed sucrose or nectar showed higher amylase activity in their honey sacs than those fed water.

CONCLUSIONS

Our data show that B. subtilis can produce amylase and offer potential for more standardized quality assessment of honey.

Rainy and Dry Seasons Are Relevant Factors Affecting Chemical and Antioxidant Properties of Meliponini Honey

Brazilian stingless bee species produce honey with distinct physicochemical and bioactive properties shaped by environmental factors. This study investigated the effects of the rainy and dry seasons on the physicochemical characteristics, chemical fingerprinting, mineral content, and antioxidant capacity of honey from Melipona mondury and Melipona bicolor. The honey samples were analyzed for their phytochemical properties (official methods), total phenolics (Folin-Ciocalteu method), flavonoid content (aluminum complex formation method), antioxidant capacity (FRAP and ABTS assays), and antioxidant activity (erythrocyte model). The mineral content was assessed via TXRF spectroscopy, and chemical fingerprinting was conducted using mass spectrometry. Chemometric tools were used for the samples' discriminating analyses, including Principal Component Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA). Seasonal variations significantly affected the moisture, total soluble solids, and acidity. In turn, the antioxidant capacity was influenced mainly by the bee species. The mineral composition, particularly potassium, phosphorus, and calcium, remained stable. Multivariate analysis identified m/z ions (VIP scores > 2.5), rather than physicochemical or antioxidant capacity parameters, as critical for seasonal discrimination. The antioxidant activity, assessed by oxidative hemolysis prevention, was robust across the seasons, with M. mondury honey (2 mg·mL-1) from the rainy season outperforming ascorbic acid. These findings underscore the impact of the rainy and dry seasons and the potential of secondary metabolite fingerprinting to identify collection periods.

Preliminary Research on the Health-Promoting Value of Honeydew Honey Enriched with Bee Bread

Since the imbalance between free radicals and antioxidants in the body plays a significant role in the physiology of common, often dangerous diseases, an emphasis is placed on enriching the daily diet with compounds characterized by antioxidant activity. Good sources of natural antioxidants are bee products such as honey, bee pollen, bee bread and propolis, and the best path for introducing the latter products into the diet is mixing them with honey. However, the characteristics of bee product mixtures are not yet fully understood. Therefore, the aim of this study is to verify the health-promoting properties of a mixture of honeydew honey and multifloral bee bread. The profile of phenolic compounds, radical scavenging activity, total phenolic content, diastase number, and also proline and HMF content were determined. The obtained results indicated the improved health-promoting value of this mixture, as increases in radical scavenging activity (from 82.7 to 88.4%), in the total content of phenolic compounds (from 74.6 to 118.8 mg·100 g-1), and also in the proline content (from 64.0 to 95.5 mg·100 g-1) and diastase activity (from 22.6 to 38.8 Schade units) were observed when 5% of bee bread (w/w) was added. Moreover, the bee bread addition provided two important flavonoids to the honeydew honey, i.e., rutin and kaempferol.

Citrus limon var. pompia Camarda var. nova: A Comprehensive Review of Its Botanical Characteristics, Traditional Uses, Phytochemical Profile, and Potential Health Benefits

Citrus limon var. pompia Camarda var. nova, commonly known as pompia, is a distinctive citrus ecotype native to Sardinia, notable for its unique botanical, phytochemical, and potential health benefits. It holds cultural significance as a traditional food product of Sardinia, recognized by the Italian Ministry of Agricultural Food and Forestry Policies. This comprehensive review examines pompia's traditional uses, taxonomic classification, pomological characteristics, phytochemical profile, and potential health benefits. Pompia phytochemical analyses reveal a rich composition of flavonoids and terpenoids, with notable concentrations of limonene, myrcene, and various oxygenated monoterpenes. Pompia essential oils are primarily extracted from its peel and leaves. Peel essential oils exhibit a high concentration of the monoterpene limonene (82%) and significantly lower quantities of myrcene (1.8%), geranial (1.7%), geraniol (1.5%), and neral (1.4%). In its rind extract, flavanones such as naringin (23.77 µg/mg), neoeriocitrin (46.53 µg/mg), and neohesperidin (44.57 µg/mg) have been found, along with gallic acid (128.3 µg/mg) and quinic acid (219.67 µg/mg). The main compounds detected in the essential oils from pompia leaves are oxygenated monoterpenes (53.5%), with limonene (28.64%), α-terpineol (41.18%), geranial (24.44%), (E)-β-ocimene (10.5%), linalool (0.56%), and neryl acetate (13.56%) being particularly prominent. In pompia juice, the presence of phenolic compounds has been discovered, with a composition more similar to lemon juice than orange juice. The primary flavonoid identified in pompia juice is chrysoeriol-6,8-di-C-glucoside (stellarin-2) (109.2 mg/L), which has not been found in other citrus juices. The compound rhoifolin-4-glucoside (17.5 mg/L) is unique to pompia juice, whereas its aglycone, rhoifolin, is found in lemon juice. Other flavonoids identified in pompia juice include diosmetin 6,8-C-diglucoside (54.5 mg/L) and isorhamnetin 3-O-rutinoside (79.4 mg/L). These findings support the potential of pompia in developing nutraceuticals and natural health products, further confirmed by its compounds' antioxidant, anti-inflammatory and antibacterial properties. Future research should focus on optimizing extraction methods, conducting clinical trials to evaluate efficacy and safety, and exploring sustainable cultivation practices. The potential applications of pompia extracts in food preservation, functional foods, and cosmetic formulations also warrant further investigation. Addressing these areas could significantly enhance pompia's contribution to natural medicine, food science, and biotechnology.

Assessment of 5-Hydroxymethylfurfural in Food Matrix by an Innovative Spectrophotometric Assay

Foods contaminants pose a challenge for food producers and consumers. Due to its spontaneous formation during heating and storage, hydroxymethylfurfural (HMF) is a prevalent contaminant in foods rich in carbohydrates and proteins. Colorimetric assays, such as the Seliwanoff test, offer a rapid and cost-effective method for HMF quantification but require careful optimization to ensure accuracy. We addressed potential interference in the Seliwanoff assay by systematically evaluating parameters like incubation time, temperature, and resorcinol or hydrochloric acid concentration, as well as the presence of interfering carbohydrates. Samples were analyzed using a UV-Vis spectrophotometer in scan mode, and data obtained were validated using HPLC, which also enabled quantification of unreacted HMF for assessing the protocol's accuracy. Incubation time and hydrochloric acid percentage positively influenced the colorimetric assay, while the opposite effect was observed with the increase in resorcinol concentration. Interference from carbohydrates was eliminated by reducing the acid content in the working reagent. HPLC analyses corroborated the spectrophotometer data and confirmed the efficacy of the proposed method. The average HMF content in balsamic vinegar samples was 1.97 ± 0.94 mg/mL. Spectrophotometric approaches demonstrated to efficiently determine HMF in complex food matrices. The HMF levels detected in balsamic vinegars significantly exceeded the maximum limits established for honey. This finding underscores the urgent need for regulations that restrict contaminant levels in various food products.

Unraveling the Physicochemical, Nutritional and Antioxidant Properties of the Honey Produced from the Fallopia japonica Plant

Fallopia japonica (FJ), commonly known as Japanese knotweed, is now recognized as one of the most invasive plants in Europe and globally. Despite its widespread presence in Europe and its significant nectar production, there is currently limited scientific data on the unique unifloral honey derived from it. This study examines the physicochemical composition of Fallopia japonica honey (FJH) samples collected from various regions in Romania. Additionally, the nutritional and antioxidant profiles of FJH were assessed. The sensory analysis revealed a honey with a brown-caramel color and an intense flavor, characterized by fine, consistent crystals during crystallization. The results indicated that FJH has a high carbohydrate content (fructose: 35.12-40.65 g/100 g; glucose: 28.06-37.79 g/100 g); elevated electrical conductivity (387-692 µS/cm), diastase activity (9.11-17.01 DN), and acidity (21.61-42.89 meq/kg); and substantial total phenolic (89.87-120.08 mg/100 g) and flavonoid (18.13-39.38 mg/g) contents. These findings highlight FJH's favorable nutritional properties, aligning with the standard codex for honey. The antioxidant profile of FJH demonstrated strong DPPH and ferric reduction antioxidant power (FRAP) activities, comparable to those of buckwheat honey, underscoring its potential health benefits and commercial value. These results provide new insights into how this invasive plant can be harnessed as a valuable resource for sustainable beekeeping practices.

The Importance of Testing the Quality and Authenticity of Food Products: The Example of Honey

The aim of this study was to review methods of honey testing in the assessment of its quality and authenticity. The quality of honey, like other food products, is multidimensional. This quality can be assessed not only on the basis of the characteristics evaluated by the consumer during purchase and consumption, but also on the basis of various physicochemical parameters. A number of research methods are used to verify the quality of honeys and to confirm their authenticity. Obligatory methods of assessing the quality of honey are usually described in legal acts. On the other hand, other, non-normative methods of honey quality assessment are used worldwide; they can be used to determine not only the elementary chemical composition of individual types of honey, but also the biological activity of honey and its components. However, so far, there has been no systematization of these methods together with a discussion of problems encountered when determining the authenticity of honeys. Therefore, the aim of our study was to collect information on the methods of assessing the quality and authenticity of honeys, and to identify the problems that occur during this assessment. As a result, a tabular summary of various research methods was created.

Quality of Commercially Available Manuka Honey Expressed by Pollen Composition, Diastase Activity, and Hydroxymethylfurfural Content

Manuka honey plays a significant role in modern medical applications as an antibacterial, antiviral, and antibiotic agent. However, although the importance of manuka honey is well documented in the literature, information regarding its physicochemical characteristics remains limited. Moreover, so far, only a few papers address this issue in conjunction with the examination of the pollen composition of manuka honey samples. Therefore, in this study, two parameters crucial for honey quality control-the diastase number (DN) and the hydroxymethylfurfural (HMF) content-as well as the melissopalynological analysis of manuka honey, were examined. The research found a large variation in the percentage of Leptospermum scoparium pollen in honeys labeled and sold as manuka honeys. Furthermore, a significant proportion of these honeys was characterized by a low DN. However, since low diastase activity was not associated with low HMF content, manuka honey should not be considered as a honey with naturally low enzymatic activity. Overall, the DN and HMF content results indicate that the quality of commercially available manuka honey is questionable.

Accelerated loss of diastase in mānuka honey: Investigation of mānuka specific compounds

Diastase is used internationally as a quality monitor for excessive heat treatment and prolonged storage of honey; honey must contain an activity of at least 8 diastase numbers (DN) for it to be considered export quality. Freshly harvested mānuka honey can have diastase activity close to the export threshold of 8 DN without excess heating, increasing susceptibility for export failure. This research investigated the effect of compounds unique to or high in concentration in mānuka honey on diastase activity. Investigation of the effect of methylglyoxal, dihydroxyacetone, 2-methoxybenzoic acid, 3-phenyllatic acid, 4-hydroxyphenyllactic acid and 2'-methoxyacetophenone on diastase activity was carried out. Mānuka honey was stored at 20 and 27 °C and clover honey spiked with compounds of interest were stored at 20, 27 and 34 °C and monitored overtime. Methylglyoxal and 3-phenyllactic acid were found to accelerate the loss of diastase above the loss normally observed with time and elevated temperature.

The Bioactive Value of Tamarix gallica Honey from Different Geographical Origins

This study was conducted to assess the bioactive value of Tamarix gallica honey samples collected from three countries. In total, 150 Tamarix gallica honey samples from Saudi Arabia (50), Libya (50), and Egypt (50) were collected and compared, based on the results of the melissopalynological analysis, their physicochemical attributes, antioxidant and antimicrobial activities, and biochemical properties, together with their total phenolic and total flavonoid contents. Depending on the geographical origin, we observed different levels of growth suppression for six resistant bacterial strains. The pathogenic microorganisms tested in this study were Staphylococcus aureus, Streptococcus mutans, Klebsiella pneumoniae, Escherichia coli, Proteus vulgaris, and Pseudomonas aeruginosa. There was a strong correlation between the polyphenol and flavonoid contents, as well as significant (p < 0.05) radical scavenging activities. The melissopalynological analysis and physicochemical properties complied with the recommendation of the Gulf and Egyptian Technical Regulations on honey, as well as the Codex Alimentarius of the World Health Organization and the European Union Normative related to honey quality. It was concluded that Tamarix gallica honey from the three countries has the capacity to suppress pathogenic bacterial growth and has significant radical scavenging activities. Moreover, these findings suggest that Tamarix gallica honey may be considered as an interesting source of antimicrobial compounds and antioxidants for therapeutical and nutraceutical industries or for food manufacturers.

Quality assessment and chemometrics application on physicochemical characteristics, antioxidant properties, and 5-HMF content of Malaysian stingless bee honey from different topographical origins

The popularity of Malaysian stingless bee honey is rising among health-conscious individuals; thus, chemical and physical evaluations of Malaysian stingless bee honey are vital to ensure the honey has achieved the optimum limits set by Malaysian and international regulatory standards so that it can be commercialized locally and internationally. Therefore, in the present study, the physicochemical characteristics (moisture content, total dissolved solids, pH, free acidity, electrical conductivity, and ash content), antioxidant properties (total phenolic and flavonoid contents), and 5-hydroxymethylfurfural (5-HMF) of Heterotrigona itama (H. itama) honey from different sites in Peninsular Malaysia were investigated. Subsequently, the correlation between these chemical and physical parameters was studied using Spearman correlation coefficients. The significant difference between H. itama honey from different topographical origins was studied using univariate analysis (one-way ANOVA followed by post hoc Tukey's test). The discrimination pattern of 45 honey samples based on their topographical origins was evaluated using cluster analysis (heatmap and dendrogram) and chemometrics analysis (partial least squares-discriminant analysis). Results showed that some samples of certain parameters (electrical conductivity, free acidity, and moisture content) have exceeded the limit set by the international regulatory standard. However, the 5-HMF content of all samples was within the allowed range. A statistically significant difference (p < 0.05) has been observed for all the parameters except electrical conductivity and ash content in terms of inter-topographical origins. Although the profiles of H. itama honey from different origins were close, most of them were separated according to their topographical origins and were validated using a permutation test.

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.

In Vitro and Predictive Computational Toxicology Methods for the Neurotoxic Pesticide Amitraz and Its Metabolites

The Varroa destructor parasite is responsible for varroasis in honeybees worldwide, the most destructive disease among parasitic diseases. Thus, different insecticides/acaricides have been widely used within beehives to control these parasitic diseases. Namely, amitraz is the most used acaricide due to its high efficacy shown against Varroa destructor. However, pesticides used for beehive treatments could be incorporated into the honey and accumulate in other hive products. Hence, honeybee health and the impairment of the quality of honey caused by pesticides have gained more attention. Amitraz and its main metabolites, N-(2,4-dimethylphenyl) formamide (2,4-DMF) and 2,4-dimethylaniline (2,4-DMA), are known to be potent neurotoxicants. In this research, the cytotoxicity of amitraz and its metabolites has been assessed by MTT and PC assays in HepG2 cells. In addition, possible target receptors by in silico strategies have been surveyed. Results showed that amitraz was more cytotoxic than its metabolites. According to the in silico ADMEt assays, amitraz and its metabolites were predicted to be compounds that are able to pass the blood-brain barrier (BBB) and induce toxicity in the central and peripheral nervous systems. The main target class predicted for amitraz was the family of A G protein-coupled receptors that comprises responses to hormones and neurotransmitters. This affects, among other things, reproduction, development, locomotion, and feeding. Furthermore, amitraz and its metabolites were predicted as active compounds interacting with diverse receptors of the Tox21-nuclear receptor signaling and stress response pathways.

Levels of Contamination by Pesticide Residues, Polycyclic Aromatic Hydrocarbons (PAHs), and 5-Hydroxymethylfurfural (HMF) in Honeys Retailed in Europe

Honey is consumed worldwide because of its nutritional, therapeutic and medicinal properties. Generally, honey should reach the consumer in a pure form, but it is often contaminated in various ways. Thus, this study was designed to check for the presence of pesticide residues, polycyclic aromatic hydrocarbon (PAH) levels, and the content of 5-hydroxymethylfurfural (HMF) in selected European honeys (26 samples) obtained from shops. The most frequently detected organochlorine pesticide (OCPs) was 4,4'-DDD, which was found in fourteen honey samples. Slovakian rapeseed honey was most polluted due to the presence of eight OCPs. The presence of organophosphorus pesticides (OPs) was detected in all the analysed samples, and at least one OP in each tested sample exceeded the acceptable limit. PAHs were detected in most of the analysed samples. As for PAH4s, benzo[a]pyrene was found in forest honey from Slovakia and in Polish lime tree honey, whereas wild flower honey from the UK contained the highest level of PAH4. The investigated honeys from Spain and France met the requirements for HMF content, while honeys of Slovak, Italian and Polish origin in most cases exceeded the established levels (40 mg/kg).

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.

Evaluation of Biological Activities and Medicinal Properties of Honey Drops and Honey Lozenges

Raw honey naturally possesses a number of health benefits that are imbued by its components, including phenolics acids, flavonoids, enzymes, sugars, and organic acids. Processing of raw honey at high temperatures, often leads to a loss of biological activity and active ingredients, hence, reducing the medicinal benefits of processed honey samples. This study describes that the processing of raw honey into honey-based candies slightly changed the physicochemical properties of raw honey, as was observed by the loss of diastase activity and reduction in hydrogen peroxide content in honey-based candies. However, the overall health benefits of honey-based candies were maintained. The processing of honey into candies (lozenges and drops) maintained antibacterial and anti-inflammatory activities of honey candies relative to the raw honey samples.

Effect of harvest time span on physicochemical properties, antioxidant, antimicrobial, and anti-inflammatory activities of Meliponinae honey

BACKGROUND

The maturity of honey has a great impact on its quality and contents. Additionally, stingless bee honey contains high moisture, which allows microorganisms to survive and ferment, contributing to honey's variable flavor and physicochemical properties. Therefore, there is a need for better quality control of the honey process, especially the harvest time of honey.

RESULTS

We gathered honey from the nest of stingless bees Heterotrigona itama and Tetrigona binghami over different time periods, i.e. 15, 30, and 45 days. The results show harvest time considerably affects the physicochemical properties, antioxidant activity, and antimicrobial activity of honey. Good antioxidant activity and antimicrobial activity can be found in honey produced from a longer harvest time. Compared with 15-day harvest time, at 30- or 45-day harvest time water, trehalulose, and protein content and total acidity increased, and the content of reducing sugars, fructose and glucose, and pH values, decreased in both types of honey. Moreover, compared with 15-day harvest time, the sum of six organic acids in the 45-day honey of H. itama fluctuated between 2.78 to 4.12 g 100 g^-1 and in the 45-day honey of T. binghami increased from 1.66 to 3.61 g 100 g^-1 , respectively.

CONCLUSION

Honey harvest time had a significant effect on the physicochemical properties, antioxidant activity, and antimicrobial activity of stingless bee honey (H. itama or T. binghami). This study provides a reference for beekeepers to adjust harvest time to obtain honey with suitable physicochemical parameters. © 2022 Society of Chemical Industry.

Kelulut Honey Ameliorates Oestrus Cycle, Hormonal Profiles, and Oxidative Stress in Letrozole-Induced Polycystic Ovary Syndrome Rats

Kelulut honey (KH) has been proven to have excellent antioxidative and anti-inflammatory properties with unique physicochemical characteristics. Therefore, we investigated the isolated and combined effects of KH, metformin, or clomiphene in alleviating oxidative stress and reproductive and metabolic abnormalities in polycystic ovary syndrome (PCOS). Female Sprague-Dawley (SD) rats were given 1 mg/kg/day of letrozole for 21 days to induce PCOS. PCOS rats were then divided into six treatment groups: untreated, metformin (500 mg/kg/day), clomiphene (2 mg/kg/day), KH (1 g/kg/day), combined KH (1 g/kg/day) and metformin (500 mg/kg/day), and combined KH (1 g/kg/day) and clomiphene (2 mg/kg/day). All treatments were administered orally for 35 days. The physicochemical characteristics of KH were assessed through hydroxymethylfurfural, free acidity, diastase number, moisture content, sugar profile, metals, and mineral compounds. Additionally, we determined the semivolatile organic compounds present in KH through gas chromatography-mass spectrometry (GC/MS) analysis. KH and its combination with metformin or clomiphene were shown to improve the oestrus cycle, hormonal profile, and oxidative stress in PCOS rats. However, KH did not reduce the fasting blood glucose, insulin, and body weight gain in PCOS rats. These findings may provide a basis for future studies to discover the potential use of KH as a complementary treatment for women with PCOS.

Exploring the Palynological, Chemical, and Bioactive Properties of Non-Studied Bee Pollen and Honey from Morocco

Bee products are known for their beneficial properties widely used in complementary medicine. This study aims to unveil the physicochemical, nutritional value, and phenolic profile of bee pollen and honey collected from Boulemane–Morocco, and to evaluate their antioxidant and antihyperglycemic activity. The results indicate that Citrus aurantium pollen grains were the majority pollen in both samples. Bee pollen was richer in proteins than honey while the inverse was observed for carbohydrate content. Potassium and calcium were the predominant minerals in the studied samples. Seven similar phenolic compounds were found in honey and bee pollen. Three phenolic compounds were identified only in honey (catechin, caffeic acid, vanillic acid) and six phenolic compounds were identified only in bee pollen (hesperidin, cinnamic acid, apigenin, rutin, chlorogenic acid, kaempferol). Naringin is the predominant phenolic in honey while hesperidin is predominant in bee pollen. The results of bioactivities revealed that bee pollen exhibited stronger antioxidant activity and effective α-amylase and α-glycosidase inhibitory action. These bee products show interesting nutritional and bioactive capabilities due to their chemical constituents. These features may allow these bee products to be used in food formulation, as functional and bioactive ingredients, as well as the potential for the nutraceutical sector.

The role of 5-hydroxymethylfurfural in food and recent advances in analytical methods

The thermal processing, storage, and transportation of foodstuffs (e.g., fruit juices, coffee, honey, and vinegar) generate 5-hydroxymethylfurfural (HMF). The food industry uses this compound as a quality marker, thus increasing the demand for fast and reliable analytical methods for its determination. This review focuses on the formation of HMF in food, its desirable and toxic effects, and recent advances in analytical methods for its determination in foodstuffs. The advantages and limitations of these analytical approaches are discussed relative to the main analytical features.

Quantitative determination of acacia honey adulteration by terahertz-frequency dielectric properties as an alternative technique

The dielectric characteristics in the terahertz region contribute to a revealing insight into the material components and provide intermolecular information. The dielectric properties of adulterated honey, described as the real and imaginary parts of the complex dielectric constant (Re[ε] and Im[ε]), were obtained from 0.3 to 1.5 THz. The relationship between invert syrup proportions and complex dielectric constants at different frequencies implied the possibility of using the dielectric property as an indicator of honey authenticity. The selected effective dielectric variables of Re[ε] and Im[ε] and their combination were chosen by stability competitive adaptive reweighted sampling (SCARS) algorithm and then used to establish PLS models. The accuracy and uncertainty result revealed SCARS-PLS model based on the combination of Re[ε] and Im[ε] is the best model relatively. These findings indicated the potential utility of this rapid, non-destructive, and on-site method for authenticity verification.

The bioactive, antioxidant, antibacterial, and physicochemical properties of a range of commercially available Australian honeys

Honey is a supersaturated sugar solution produced from plant nectar, with its composition influenced by geographic and floral origins, and with several properties contributing to its health-related abilities. This study aimed to determine the bioactive composition, antioxidant characteristics, antibacterial activity, and physicochemical properties of commercial Australian honeys. In total, 42 commercial Australian honeys were selected, and categorised according to front-label descriptions. Honeys were analysed: quality (Hydroxymethylfurfural); colour (colour intensity, L*,a*,b*); bioactive composition (phenolic, flavonoid, and carotenoid content); antioxidant characteristics (DPPH, CUPRAC, FRAP); antibacterial activity (MIC50); physicochemical properties (pH, TSS, viscosity, a w). Colour intensity correlated with each assessed bioactive compound and antioxidant characteristic (p ≤ 0.001). MIC50 (S. aureus) was associated with FRAP and a w, suggesting mechanisms of action for honey's antibacterial activity. Manuka-type honeys had higher colour intensity (1440 (98.5) mAU) than other categories (p ≤ 0.05), and consistently higher bioactive and antioxidant properties. This provides the potential to inform antioxidant-related health outcomes.

Meliponinae and Apis mellifera honey in southern Brazil: Physicochemical characterization and determination of pesticides

This study evaluated the physicochemical parameters and the occurrence of pesticides in multi-flower honey produced by six species of Meliponinae and Apis mellifera and collected in different seasons, floral species and sites in southern Brazil. Meliponinae honey were found to exhibit higher moisture, free acidity and sucrose concentration and lower concentration of reducing sugars than the standard of Apis mellifera honey in Brazil. Regarding Apis mellifera honey, reducing sugars and sucrose did not comply with the legislation. The Principal Component Analysis (PCA) showed that most of the composition variability was defined by free acidity, moisture, soluble solids, fructose, glucose, and reducing sugars. Determination of pesticides was carried out by the citrate QuEChERS method and gas chromatography tandem mass spectrometry (GC-MS/MS). However, no pesticide residues at concentrations above the limit of quantification were found in the twenty honey samples. Results show that this region has the potential to produce honey.

The Influence of Chemical Contaminants on the Physicochemical Properties of Unifloral and Multifloral Honey

The aim of this study was to evaluate and compare the effect of antibiotic and pesticide residues on the physicochemical properties of unifloral and multifloral honey. The mineral elements content of honey was analyzed and correlated with antibiotic and pesticide residues, and a positive correlation was found between manganese and neonicotinoids. Potassium was found to be the most abundant mineral compound. Correlations were found between mineral content, color, and the content of antibiotic and pesticide residues of honey. In meadow honey, residues of antibiotics and pesticides were undetectable. In some of the other types of honey, the maximum residue limits regulated by European legislation were exceeded. Endosulfan residue was found in mint and rapeseed, honey with 0.42 and 5.14 ng/g, respectively. Neonicotinoids were found in 27% of the analyzed honey samples. Chloramphenicol was identified only in rapeseed honey, with concentrations ranging from 0.2 ng/g to 0.8 ng/g. Nitrofurans were found in 14%, and nitroimidazoles were found in 6% of the analyzed samples. According to EU legislation that is in force, the use of antibiotics in beekeeping is not allowed. The MRLs for neonicotinoids are 50 ng/g, and for coumaphos, the maximum limit is 100 ng/g. For the other pesticide residues, the maximum limit is 10 ng/g. The results of statistical analysis obtained using principal component analysis (PCA) showed a major difference in the levels of contamination of raspberry and meadow honey and the other types of honey.

Chemical Analyses and Antimicrobial Activity of Nine Kinds of Unifloral Chinese Honeys Compared to Manuka Honey (12+ and 20+)

Honey has good antimicrobial properties and can be used for medical treatment. The antimicrobial properties of unifloral honey varieties are different. In this study, we evaluated the antimicrobial and antioxidant activities of nine kinds of Chinese monofloral honeys. In addition, headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) technology was used to detect their volatile components. The relevant results are as follows: 1. The agar diffusion test showed that the diameter of inhibition zone against Staphylococcus aureus of Fennel honey (21.50 ± 0.41 mm), Agastache honey (20.74 ± 0.37 mm), and Pomegranate honey (18.16 ± 0.11 mm) was larger than that of Manuka 12+ honey (14.27 ± 0.10 mm) and Manuka 20+ honey (16.52 ± 0.12 mm). The antimicrobial activity of Chinese honey depends on hydrogen peroxide. 2. The total antioxidant capacity of Fennel honey, Agastache honey, and Pomegranate honey was higher than that of other Chinese honeys. There was a significant positive correlation between the total antioxidant capacity and the total phenol content of Chinese honey (r = 0.958). The correlation coefficient between the chroma value of Chinese honey and the total antioxidant and the diameter of inhibition zone was 0.940 and 0.746, respectively. The analyzed dark honeys had better antimicrobial and antioxidant activities. 3. There were significant differences in volatile components among Fennel honey, Agastache honey, Pomegranate honey, and Manuka honey. Hexanal-D and Heptanol were the characteristic components of Fennel honey and Pomegranate honey, respectively. Ethyl 2-methylbutyrate and 3-methylpentanoic acids were the unique compounds of Agastache honey. The flavor fingerprints of the honey samples from different plants can be successfully built using HS-GC-IMS and principal component analysis (PCA) based on their volatile compounds. Fennel honey, Agastache honey, and Pomegranate honey are Chinese honey varieties with excellent antimicrobial properties, and have the potential to be developed into medical grade honey.

Physicochemical properties, total phenolic content, and antioxidant activity of chestnut, rhododendron, acacia and multifloral honey

The aim of this study is to investigate the physicochemical properties, antioxidant activities, and total phenolic contents of the plateau (multifloral), chestnut, rhododendron, and acacia honey collected from Ordu province in Turkey. The rhododendron honey had the highest acidity (p < 0.05) while the chestnut honey showed the highest conductivity (1.13 ± 0.25 mS/cm) among all (p < 0.05). The highest diastase activities and the lowest HMF contents were determined in the multifloral and chestnut honey. Considering the DPPH and FRAP assays, the multifloral honey showed the highest antioxidant activity. Accordingly, the highest total phenolic content was determined in the multifloral honey followed by rhododendron, chestnut, and acacia honey. A moderate correlation was determined between the total phenolic content and antioxidant activities (r = 0.575 for FRAP and r = 0.697 for DPPH). Consequently, the plateau honey could be recommended for nutritional and health purposes due to its relatively higher antioxidant activity and total phenolic content together with relatively lower HMF content and higher diastase activity. Considering that Ordu is the largest honey producer city in Turkey, the second top honey producer country, this work could shed light for future studies and be taken as a reference providing insights on the characteristics of different types of honey for both local and worldwide producers.

The sources and quality of Iranian honey

Iran is one of the largest honey-producing countries worldwide and is considered as an important source of honey for international markets. However, since Iran is not registered for honey export to Europe, the quality of Iranian honey remains unknown to European traders. As the first step in filling this gap, we analyzed 225 honey samples using palynology, sensory, nuclear magnetic resonance (NMR) and conventional physicochemical analyses as outlined by the European Union coordinated control plan. The results show that while various types of genuine unifloral honey can be harvested in Iran, 85% of collected samples were adulterated. Performing principal component analysis on physicochemical parameters reveals that feeding tablet sugar and syrup of C4 origin to bees during the foraging season is a common mode of fraud. Replacement of natural nectar with sugar syrup together with presence of intensive aftertaste from Taraxacum and Eryngium affect the taste of unifloral honeys produced in Iran.

Polymer film as starch azure container for the easy diastase activity determination in honey

A new original application for a polyacrylic film based on the monomers 2-(dimethylamino)ethyl methacrylate (NNDA), 2-hydroxyethyl acrylate (2HEA) and methylmethacrylate (MMA) as a starch azure container has been set up for a simple determination of honey diastase activity. The proposed method is based on the correlation of reducing sugars generated during the enzymatic process with the Schade reference assay. The polyacrylic film is charged with starch azure acting as a container for this substance; thus, the starch does not interfere in the measurement of reducing sugars, so that the diastase activity is easily calculated. The method has been contrasted with Schade method, showing good correlation and differences under 0.4% between methods in some honey samples. The polyacrylic film has great potential for the routine honey diastase activity assessment in small laboratories, dramatically reducing analysis time and cost.

A single honey proteome dataset for identifying adulteration by foreign amylases and mining various protein markers natural to honey

Honey adulteration is a common practice that deceives consumers and devalues the unique curative and food properties of honey. For marketing, each honey must satisfy an internationally valid Codex standard. One of the quality parameters is diastase/amylase activity, which, if lowered, may be compensated for by the addition of foreign amylases. However, the estimation of enzyme activity does not enable identification of artificially added amylases. 45 honey samples were analyzed using label-free nanoLC-MS/MS proteomics. Four honeys were found to contain the foreign amylases from Aspergillus niger, Bacillus amyloliquefaciens and/or Bacillus licheniformis. This result was confirmed via proof of specificity at multiple levels. Furthermore, we identified a series of plant-related protein groups. Despite plant-related proteins constituting a significant portion of honey proteins, they were minor components compared to the major honey bee-derived proteins. Bioinformatic analysis also provided evidence for aphid and catalase proteins in honey, but the limited specificity of the MS/MS identified peptides must be considered. Overall, we demonstrate a proteomics approach employing LC-MS/MS that is useful for proving adulteration and assessing honey quality. As an resource useful for reference, we provide curated sequence databases. In addition, we provide many markers that are naturally found in honey for future studies. SIGNIFICANCE: Honey is unique natural product used since ancient times as a food and natural medicine. Humans strive to understand honey components because they can characterize different types of honey and be used for authentication and origin assessment. One of the important honey components are proteins. The proteins present in honey can naturally occur in honey, but some of them can be used to mask deficiencies in some honey quality properties. Diastases/amylases are such proteins, and their activity, a measure of honey freshness, can decrease in time or due to processing. To our knowledge, we for the first time specifically identify foreign amylases in honey. However, this study provided new information on other non-honey bee proteins in honey. Thus, this study is also of importance due to its identification of plant and aphid proteins and catalase-related proteins. This study provides a clue explaining the controversial presence of catalase in honey, since catalases can be identified and their origin determined via proteomics.

Antibacterial activity and characterisation of some Egyptian honey of different floral origin

The aim of the current study was to evaluate the antibacterial activity and to analyse the physicochemical properties of some Egyptian honey of different botanical origin in comparison with Manuka honey from New Zealand. Antibacterial activity of Egyptian honey of different floral origin was evaluated against five reference bacterial strains including both Gram-positive and Gram-negative bacteria using well diffusion method. Pollen analysis was used to confirm the floral origin of honey. Meanwhile, the physicochemical parameters including total phenolic and total flavonoid contents were measured to assess the quality of honey. Some honey types including Flowers, Aashab, Bardakosh, and Black seed honey showed significant antibacterial activity against Staphylococcus aureus (ATCC 25923) when compared with clindamycin. The same types of honey, except Black seed honey exhibited significant antibacterial activity against Citrobacter diversus (ATCC 13315). The total phenolic and total flavonoid contents ranged from 130.5±9.0 to 175.3±11.3 mg GAE/100 g honey and 22.3±1.7–30.9±2.6 mg RE/100 g honey, respectively. The results indicated that Egyptian honey is a promising natural product that can be potentially used as an alternative to synthetic antibiotics. Authentication of honey through the investigation of its physicochemical characteristics is a very important determinant of its biological activity. Separation and investigation of the antimicrobial activity of each of the active compounds of honey will provide more information on the efficacy and the mechanism of its biological activity. Further studies are still needed to identify and standardise protocols for the use of honey either in the protection against or the treatment of microbial infections.