Characterization of Eucalyptus, Chestnut and Heather Honeys from Portugal Using Multi-Parameter Analysis and Chemo-Calculus

Chemical Profiles and Biological Effects of Polyphenols in Eucalyptus Genus: A Comprehensive Review on Their Applications in Human Health and the Food Industry

The genus Eucalyptus is an important member of the family Myrtaceae. Eucalyptus plants contain unique and diverse phytochemicals, contributing to their remarkable ecological and economic values. Although the chemical components of several Eucalyptus food products (e.g., essential oil, honey, and wax) have been studied, research efforts are directed to other less characterized Eucalyptus phytochemicals, particularly polyphenols. Notably, some Eucalyptus polyphenols, such as formyl phloroglucinol meroterpenoids, have unique chemical structures with promising health-promoting effects. Thus, chemical characterization and biological evaluation of Eucalyptus polyphenols are critical to promoting their applications. Herein, this review provides a comprehensive summary of the phytochemical studies of Eucalyptus polyphenols and their biological activities, including antimicrobial, antiviral, anticancer, antioxidant, and anti-inflammatory effects. Eucalyptus polyphenols' structure-activity relationship is analyzed in the context of the development of their biological applications. In addition, the utilization of polyphenols from Eucalyptus plants in food preservation and production is summarized.

Quantifying the Impact of High-Pressure Processing on the Phenolic Profile, Antioxidant Activity, and Pollen Morphology in Honey

Honey can benefit from non-thermal processing techniques such as high-pressure processing (HPP) to improve its quality and bioactivity. This study investigated the impact of HPP (600 MPa for 5, 10, and 15 min) on honey's quality, including the levels of hydroxymethylfurfural (HMF), antioxidant activity, total phenolic content (TPC), and phenolic profile. HPP treatment did not significantly affect HMF or TPC levels but led to selective changes in the phenolic profile. Despite a reduction in certain phenolic compound content, HPP for 5 and 15 min caused a significant increase in the antioxidant activity (2,2-diphenyl-1-picrylhydrazyl [DPPH]) of honey from the mean value of 41.8% to values of 45.4% and 49.6%, respectively. On the other hand, HPP for 10 min did not change the antioxidant activity of tested honey. A 27.5% reduction in the equatorial diameter of pollen grains was observed after HPP combined with temperature at 75°C, suggesting an improved release of bioactive compounds. The content of specific phenolic compounds, including caffeic acid, p-coumaric acid, sinapic acid, naringin, kaempferol, and the TPC, significantly affected the DPPH activity. The increment in the antioxidant activity of HPP honey may be attributed to selective changes in the content of certain phenolic compounds and improved their extraction from pollen grains.

Analysis of the Volatile and Enantiomeric Compounds Emitted by Plumeria rubra L. Flowers Using HS-SPME-GC

The volatile components emitted by fresh aromatic flowers of Plumeria rubra L., harvested in southern Ecuador during three different months were determined to evaluate the fluctuation of secondary metabolites. The volatile compounds were analyzed using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography coupled to mass spectrometry (GC-MS) and a flame ionization detector (GC-FID) using two types of columns: a non-polar (DB-5ms) and polar column (HP-INNOWax). The principal chemical groups were hydrocarbon sesquiterpenes (43.5%; 40.0%), oxygenated sesquiterpenes (23.4%; 26.4%), oxygenated monoterpenes (14.0%; 11.2%), and hydrocarbon monoterpenes (12.7%; 9.3%). The most representative constituents were (E,E)-α-Farnesene (40.9-41.2%; 38.5-50.6%), (E)-nerolidol (21.4-32.6%; 23.2-33.0%), (E)-β-ocimene (4.2-12.5%; 4.5-9.1%), (Z)-dihydro-apofarnesol (6.5-9.9%; 7.6-8.6%), linalool (5.6-8.3%; 3.3-7.8%), and perillene (3.1-5.9%; 3.0-3.2%) in DB-5ms and HP-INNOWax, respectively. Finally, we reported for the first time the enantiomeric distribution of P. rubra flowers, where the enantiomers (1R,5R)-(+)-α-pinene, (S)-(-)-limonene, (S)-(+)-Linalool, and (1S,2R,6R,7R,8R)-(+)-α-copaene were present as enantiomerically pure substances, whereas (S)-(+)-(E)-Nerolidol and (R)-(+)-(E)-Nerolidol were observed as scalemic mixtures. This study provides the first comprehensive and comparative aroma profile of Plumeria rubra cultivated in southern Ecuador and gave us a clue to the variability of P. rubra chemotypes depending on the harvesting time, which could be used for future quality control or applications in phytopharmaceutical and food industries.

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.

Effect of Temperature and Time on the Physicochemical and Sensory Properties of Crystallized Honey

This research explores the crystallization process of honey during storage with a focus on its dissolution dynamics and essential characteristics. The investigation includes the examination of the effects of heat treatment at different temperatures (45-90 °C) and durations (23-960 min) on the induced crystallization of honey at 14 °C. Various analyses were conducted, including pH, acidity, color, sugar profile, phenolic and flavonoid contents, DPPH-scavenging activity, hydroxymethylfurfural (HMF), viscosity, and sensory attributes. The results indicated a reduction in the moisture content and pH, an increase in acidity, and higher levels of HMF at elevated temperatures. While the ash content remained relatively unchanged, variables such as color, glucose, fructose, total phenol, flavonoid, and antioxidant content exhibited variations with temperature. Viscosity decreased with an increase in temperature, suggesting Newtonian behavior and implying potential colloidal changes. Consumer sensory tests revealed significant differences among samples, with honey treated at 75 °C demonstrating superior physicochemical and sensory attributes. This study offers valuable insights into the dynamics of crystallized honey, providing information for both production practices and understanding consumer preferences.

Bioactivities and Phenolic Profiles of Honeys Derived from Plants of the Goldfields, Esperance and Wheatbelt Regions of Western Australia

The aim of this study was to examine a collection of 79 honeys derived from plants endemic to several Western Australian unique bioregions for bioactivity and physicochemical characteristics. For physicochemical analyses, total phenolic content, high performance thin layer chromatography (HPTLC) fingerprints, pH, Brix, colour and hydrogen peroxide generation were examined. Brix (82.6±1.3) and pH (4.34±0.24) values were within expected ranges, whereas hydrogen peroxide levels determined using an o-dianisidine/horseradish peroxidase assay were relatively low, ranging from 0-244 μM. Antibacterial activity determined by the broth microdilution assay showed that Moort (Eucalyptus platypus) and Yate (Eucalyptus occidentalis) honeys had the highest overall activity with mean minimum inhibitory concentrations of 24.8 % and 25.1 % (w/v) honey, respectively. Yate honey also had the highest overall antioxidant activity (4.38±0.58 mmol Fe2+ /kg of honey), followed by Mallee honeys from various eucalypts, as determined by FRAP (Ferric reducing antioxidant power) and DPPH⋅ (2,2-Diphenyl-1-picrylhydrazyl) assays. This study identified new sources of honeys with potentially useful therapeutic properties from bioregions within Western Australia.

Chemometric classification of chestnut honeys from different regions in Turkey based on their phenolic compositions and biological activities

The objective of this study was to investigate the phenolic composition and biological properties of chestnut honeys of 41 stations in Turkey's the Black Sea and Marmara regions. A total of sixteen phenolic compounds and organic acids were detected using HPLC-DAD and levulinic, gallic, protocatechuic, vanilic, trans-cinnamic acids and (4-hydroxyphenyl) ethanol were identified in all studied chestnut honeys. Antioxidant activities were measured by ABTS^•+, β-carotene-linoleic acid, CUPRAC, DPPH^•, and metal chelating assays. Antimicrobial activities were carried out against gram positive, gram negative bacteria and Candida species using well diffusion test. Anti-inflammatory activities were evaluated against COX-1 and COX-2 whereas enzyme inhibitory activities were assessed on AChE, BChE, urease, and tyrosinase. The chemometric classification of chestnut honeys were carried out using PCA and HCA and it was seen that some phenolic compounds contributed significantly to the classification of chestnut honeys from various geographical origin.

Thymol@activated Carbon Nanohybrid for Low-Density Polyethylene-Based Active Packaging Films for Pork Fillets' Shelf-Life Extension

Τhe replacement of food packaging additives and preservatives with bio-based antioxidant/antibacterial compounds has been a common practice in recent years following the trend of bioeconomy and nanotechnology. Such bio-additives are often enclosed in nanocarriers for a controlled release process. Following this trend in this work, a thymol (TO)-rich activated carbon (AC) nanohybrid was prepared and characterized physicochemically with various techniques. This TO@AC nanohybrid, along with the pure activated carbon, was extruded with low-density polyethylene (LDPE) to develop novel active packaging films. The codenames used in this paper were LDPE/xTO@AC and LDPE/xAC for the nanohybrid and the pure activated carbon, respectively. X-ray diffractometry, Fourier-transform infrared spectroscopy, and scanning electron microscopy measurements showed high dispersity of both the TO@AC nanohybrid and the pure AC in the LDPE matrix, resulting in enhanced mechanical properties. The active film with 15 wt.% of the TO@AC nanohybrid (LDPE/15TO@AC) exhibited a 230% higher water/vapor barrier and 1928% lower oxygen permeability than the pure LDPE film. For this active film, the highest antioxidant activity referred to the DPPH assay (44.4%), the lowest thymol release rate (k₂ ≈ 1.5 s^-1), and the highest antibacterial activity were recorded, resulting in a 2-day extension of fresh pork fillets' shelf-life.

Multivariate Statistical Approach for the Discrimination of Honey Samples from Galicia (NW Spain) Using Physicochemical and Pollen Parameters

Raw honey is a food with a close relation to the territory in which it is produced because of factors such as soil conditions, weather patterns, and plant communities living in the area together. Furthermore, beekeeping management affects the properties of honey. Protected Geographical Indication Miel de Galicia protects the honey produced in Galicia (Northwest Spain). Various types of honeys (362 samples) from this geographical area were analyzed using chemometric techniques. Principal component analysis was favorable to analyzing the physicochemical and pollen variables with the greatest weight in the differentiation of honey. The linear discriminant analysis correctly classified 89.8% of the samples according to the botanical origin using main pollen spectra and physicochemical attributes (moisture, pH, electrical conductivity, diastase content, phenols, flavonoids, and color). Regarding unifloral honey, blackberry, eucalyptus, and heather honeys were correctly grouped, while five chestnut honeys and fourteen samples of honeydew honeys were misclassified. The chestnut and honeydew honeys have similar physicochemical properties and frequently similar pollen spectra profiles complicating the differentiation. Experimental evidence suggests the potential of multivariate statistics in the characterization of honey of the same geographical origin. Therefore, the classification results were good, with electrical conductivity, total phenol content, total flavonoid content and dominant pollens Eucalyptus, Erica, Rubus and Castanea sativa as the variables of higher importance in the differentiation of botanical origin of honeys.

Characterization of Turkish pine honey according to their geographical origin based on physicochemical parameters and chemometrics

This study was conducted to determine the characteristic properties of Turkish pine honey, which is an important honeydew honey. The geographical classification of the honey was determined by applying carbon isotope, melissopalynological, and physicochemical analyses to 373 samples collected from 47 regions between 2015 and 2017 under controlled conditions. δ13C protein-δ13Choney, C4%, electrical conductivity, moisture, ash, free acidity, color CIEL* a*b attributes, optical rotation [α]20, proline, diastases activities, and sugars (fructose, glucose, sucrose, and maltose) were used as physicochemical properties. Number of honeydew elements /number of total pollen (NHE/NTP) ratios were studied at melissopalynological analyses. The results showed that all samples exhibited honeydew properties, and that all physicochemical parameters met the criteria set by regulatory standards for honeydew. However, C4% sugar and δ13C protein-δ13C honey values did not meet the regulatory criteria and exhibited quite wide standard deviations.

In Vivo Anti-Alzheimer and Antioxidant Properties of Avocado (Persea americana Mill.) Honey from Southern Spain

There is growing evidence that Alzheimer's disease (AD) can be prevented by reducing risk factors involved in its pathophysiology. Food-derived bioactive molecules can help in the prevention and reduction of the progression of AD. Honey, a good source of antioxidants and bioactive molecules, has been tied to many health benefits, including those from neurological origin. Monofloral avocado honey (AH) has recently been characterized but its biomedical properties are still unknown. The aim of this study is to further its characterization, focusing on the phenolic profile. Moreover, its antioxidant capacity was assayed both in vitro and in vivo. Finally, a deep analysis on the pathophysiological features of AD such as oxidative stress, amyloid-β aggregation, and protein-tau-induced neurotoxicity were evaluated by using the experimental model C. elegans. AH exerted a high antioxidant capacity in vitro and in vivo. No toxicity was found in C. elegans at the dosages used. AH prevented ROS accumulation under AAPH-induced oxidative stress. Additionally, AH exerted a great anti-amyloidogenic capacity, which is relevant from the point of view of AD prevention. AH exacerbated the locomotive impairment in a C. elegans model of tauopathy, although the real contribution of AH remains unclear. The mechanisms under the observed effects might be attributed to an upregulation of daf-16 as well as to a strong ROS scavenging activity. These results increase the interest to study the biomedical applications of AH; however, more research is needed to deepen the mechanisms under the observed effects.

Monitoring the effects of field exposure of acetamiprid to honey bee colonies in Eucalyptus monoculture plantations

Eucalyptus plantations occupy 26 % of Portuguese forested areas. Its flowers constitute important sources for bees and beekeepers take advantage of this and keep their honey bee colonies within or near the plantations for honey production. Nonetheless, these plantations are susceptible to pests, such as the eucalyptus weevil Gonipterus platensis. To control this weevil, some plantations must be treated with pesticides, which might harm non-target organisms. This study aimed to perform a multifactorial assessment of the health status and development of Apis mellifera iberiensis colonies in two similar landscape windows dominated by Eucalyptus globulus plantations - one used as control and the other with insecticide treatment. In each of the two selected areas, an apiary with five hives was installed and monitored before and after a single application of the insecticide acetamiprid (40 g a.i./ha). Colony health and development, resources use, and pesticide residues accumulation were measured. The results showed that the application of acetamiprid in this area did not alter the health status and development of the colonies. This can be explained by the low levels of residues of acetamiprid detected only in pollen and bee bread samples, ~52 fold lower than the sublethal effect threshold. This could be attributed to the low offer of resources during and after the application event and within the application area, with the consequent foraging outside the sprayed area during that period. Since exposure to pesticides in such complex landscapes seems to be dependent on the spatial and temporal distribution of resources, we highlight some key monitoring parameters and tools that are able to provide reliable information on colony development and use of resources. These tools can be easily applied and can provide a better decision-taking of pesticide application in intensive production systems to decrease the risk of exposure for honey bees.

Calluna vulgaris as a Valuable Source of Bioactive Compounds: Exploring Its Phytochemical Profile, Biological Activities and Apitherapeutic Potential

Calluna vulgaris, belonging to the Ericaceae family, is an invasive plant that has widely spread from Europe all across Asia, North America, Australia and New Zealand. Being able to survive in rigid soil and environmental conditions, it is nowadays considered to be of high nature-conservation value. Known for its nutritional and medicinal properties, C. vulgaris stands out for its varied physiochemical composition, spotlighting a wide range of biological activity. Among the most important bioactive compounds identified in C. vulgaris, the phenolic components found in different parts of this herbaceous plant are the main source of its diverse pro-health properties (antioxidant, anti-inflammatory, antimicrobial, chemoprotective, etc.). Nonetheless, this plant exhibits an excellent nectariferous potential for social insects such as honeybees; therefore, comparing the bioactive compounds observed in the plant and in the final product of the beehive, namely honey, will help us understand and find new insights into the health benefits provided by the consumption of C. vulgaris-related products. Thus, the main interest of this work is to review the nutritional profile, chemical composition and biological activities of the C. vulgaris plant and its related honey in order to encourage the future exploration and use of this health-promoting plant in novel foods, pharmacological products and apitherapy.

Effect-Directed Profiling of Monofloral Honeys from Ethiopia by High-Performance Thin-Layer Chromatography and High-Resolution Mass Spectrometry

Ethiopian honey is used not only as food but also for treatment in traditional medicine. For its valorization, bioactive compounds were analyzed in nine types of monofloral Ethiopian honey. Therefore, a non-target effect-directed profiling was developed via high-performance thin-layer chromatography combined with multi-imaging and planar effect-directed assays. Characteristic bioactivity profiles of the different honeys were determined in terms of antibacterial, free-radical scavenging, and various enzyme inhibitory activities. Honeys from Hypoestes spp. and Leucas abyssinica showed low activity in all assays. In contrast, others from Acacia spp., Becium grandiflorum, Croton macrostachyus, Eucalyptus globulus, Schefflera abyssinica, Vernonia amygdalina, and Coffea arabica showed more intense activity profiles, but these differed depending on the assay. In particular, the radical scavenging activity of Croton macrostachyus and Coffea arabica honeys, the acetylcholinesterase-inhibiting activity of Eucalyptus globulus and Coffea arabica honeys, and the antibacterial activity of Schefflera abyssinica honey are highlighted. Bioactive compounds of interest were further characterized by high-resolution mass spectrometry. Identifying differences in bioactivity between mono-floral honey types affects quality designation and branding. Effect-directed profiling provides new insights that are valuable for food science and nutrition as well as for the market, and contributes to honey differentiation, categorization, and authentication.

Determination of Floral Origin Markers of Latvian Honey by Using IRMS, UHPLC-HRMS, and 1H-NMR

The economic significance of honey production is crucial; therefore, modern and efficient methods of authentication are needed. During the last decade, various data processing methods and a combination of several instrumental methods have been increasingly used in food analysis. In this study, the chemical composition of monofloral buckwheat (Fagopyrum esculentum), clover (Trifolium repens), heather (Calluna vulgaris), linden (Tilia cordata), rapeseed (Brassica napus), willow (Salix cinerea), and polyfloral honey samples of Latvian origin were investigated using several instrumental analysis methods. The data from light stable isotope ratio mass spectrometry (IRMS), ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS), and nuclear magnetic resonance (NMR) analysis methods were used in combination with multivariate analysis to characterize honey samples originating from Latvia. Results were processed using the principal component analysis (PCA) to study the potential possibilities of evaluating the differences between honey of different floral origins. The results indicate the possibility of strong differentiation of heather and buckwheat honeys, and minor differentiation of linden honey from polyfloral honey types. The main indicators include depleted δ¹⁵N values for heather honey protein, elevated concentration levels of rutin for buckwheat honey, and qualitative presence of specific biomarkers within NMR for linden honey.

Volatile Profile of Portuguese Monofloral Honeys: Significance in Botanical Origin Determination

The volatile profiles of 51 samples from 12 monofloral-labelled Portuguese honey types were assessed. Honeys of bell heather, carob tree, chestnut, eucalyptus, incense, lavender, orange, rape, raspberry, rosemary, sunflower and strawberry tree were collected from several regions from mainland Portugal and from the Azores Islands. When available, the corresponding flower volatiles were comparatively evaluated. Honey volatiles were isolated using two different extraction methods, solid-phase microextraction (SPME) and hydrodistillation (HD), with HD proving to be more effective in the number of volatiles extracted. Agglomerative cluster analysis of honey HD volatiles evidenced two main clusters, one of which had nine sub-clusters. Components grouped by biosynthetic pathway defined alkanes and fatty acids as dominant, namely n-nonadecane, n-heneicosane, n-tricosane and n-pentacosane and palmitic, linoleic and oleic acids. Oxygen-containing monoterpenes, such as cis- and trans-linalool oxide (furanoid), hotrienol and the apocarotenoid α-isophorone, were also present in lower amounts. Aromatic amino acid derivatives were also identified, namely benzene acetaldehyde and 3,4,5-trimethylphenol. Fully grown classification tree analysis allowed the identification of the most relevant volatiles for discriminating the different honey types. Twelve volatile compounds were enough to fully discriminate eleven honey types (92%) according to the botanical origin.

Establishing Relationship between Vitamins, Total Phenolic and Total Flavonoid Content and Antioxidant Activities in Various Honey Types

Honey is a well-known natural sweetener and is rich in natural antioxidants that prevent the occurrence of oxidative stress, which is responsible for many human diseases. Some of the biochemical compounds in honey that contribute to this property are vitamins and phenolic compounds such as phenolic acids and flavonoids. However, the extent to which these molecules contribute towards the antioxidant capacity in vitro is inconsistently reported, especially with the different analytical methods used, as well as other extrinsic factors that influence these molecules' availability. Therefore, by reviewing recently published works correlating the vitamin, total phenolic, and flavonoid content in honey with its antioxidant activities in vitro, this paper will establish a relationship between these parameters. Based on the literature, vitamins do not contribute to honey's antioxidant capacity; however, the content of phenolic acids and flavonoids has an impact on honey's antioxidant activity.

The antimicrobial activity of polyfloral honey and its awareness among urban consumers in Slovakia

The current interdisciplinary research studies the antimicrobial activity of selected polyfloral kinds of honey (n = 30) against three microorganisms (gram-positive bacteria Enterococcus faecalis, gram-negative bacteria Salmonella enterica, and one yeast Candida krusei) as well as investigates consumer behavior and awareness towards honey healing properties. Consumer research involved 617 honey consumers living in urban areas. T-test for Equality of means, non-parametric tests, and descriptive statistics were applied. Results showed that antimicrobial activity was found in all honey samples with a concentration of 50%. Nevertheless, better activity was obtained in honey samples from urban beekeepers compared to samples from retail stores. Results of consumer research showed that honey is mostly used as food (sweetener in beverages, ingredient in the recipe, or direct consumption) and as medicine mainly during the winter period. The consumer awareness towards honey healing effects was very high (97%), however, 1/3 of respondents were not able to list any specific examples, and only 11 % mentioned antibacterial activity. Furthermore, more than 70% of respondents did not know to explain the term “medical honey” and more than 50% of respondents are not aware of the maximum temperature used for heating honey without decreasing its biologically active compounds.

Antibiofilm Activity of Heather and Manuka Honeys and Antivirulence Potential of Some of Their Constituents on the DsbA1 Enzyme of Pseudomonas aeruginosa

Heather honey was tested for its effect on the formation of biofilms by Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Salmonella Enteriditis and Acinetobacter baumanii in comparison with Manuka honey. At 0.25 mg/mL, Heather honey inhibited biofilm formation in S. aureus, A. baumanii, E. coli, S. Enteriditis and P. aeruginosa, but promoted the growth of E. faecalis and K. pneumoniae biofilms. Manuka honey inhibited biofilm formation in K. pneumoniae, E. faecalis, and S. Enteriditis, A. baumanii, E. coli and P. aeruginosa, but promoted S. aureus biofilm formation. Molecular docking with Autodock Vina was performed to calculate the predictive binding affinities and ligand efficiencies of Manuka and Heather honey constituents for PaDsbA1, the main enzyme controlling the correct folding of virulence proteins in Pseudomonas aeruginosa. A number of constituents, including benzoic acid and methylglyoxal, present in Heather and/or Manuka honey, revealed high ligand efficiencies for the target enzyme. This helps support, to some extent, the decrease in P. aeruginosa biofilm formation observed for such honeys.

Use of kinetic data to model potential antioxidant activity: Radical scavenging capacity of Australian Eucalyptus honeys

Antioxidant activity of honeys may be beneficial in wound healing processes by protecting cells against lipid oxidation. The DPPH assay assesses the efficacy of antioxidant molecules to reduce DPPH^• to DPPHH. Studies determining EC₅₀ are limited by single time-point determinations of antioxidant effect and can miss vital information about the rate of antioxidant response. Acquisition of kinetic data allows determination of the radical scavenging capacity (RSC) of honeys. The purpose of this study was to determine the RSC of 53 honeys from 16 species of Australian Eucalyptus trees and four samples of New Zealand manuka (Leptospermum scoparium) honey. Whereas honeys could not be differentiated based on EC₅₀ values, significant differences were observed for RSC, supporting collection of kinetic data for honey analysis. The greatest RSC was observed for New Zealand manuka (4.6 ± 0.3 × 10^-5 mg.mL^-1.min^-1), grey ironbark (E. paniculate; 3.4 ± 0.2 × 10^-5 mg.mL^-1.min^-1) and river red gum honeys (E. camaldulensis; 3.2 ± 0.2 × 10^-5 mg.mL^-1.min^-1).

Description of the volatile fraction of Erica honey from the northwest of the Iberian Peninsula

Heather honey is highly appreciated by consumers for its sensorial profile, which varies depending on the flora used by the honeybees. Volatile compounds contribute to these qualities. Characterisation of the volatile profile related to the botanical origin is of great interest for the standardization of unifloral honey. For this reason, 33 heather honey samples from northwest of the Iberian Peninsula were analysed by headspace solid-phase microextraction (HS-SPME) to identify the key volatile compounds in this type of honey. The aim of this research was to provide a descriptive analysis of these compounds, and to find whether there is any relationship with the main Erica species. A total of 58 volatile organic compounds were found, with hotrienol, phenylacetaldehyde, and cis-linalool being the most abundant. A principal component analysis and Spearman's rank correlation showed the homogeneity of the volatile profile in the samples, and their close relationship with the main pollen types.

Botanical Origin, Pollen Profile, and Physicochemical Properties of Algerian Honey from Different Bioclimatic Areas

The palynological and physicochemical analysis of 62 honey samples produced in different biogeographical areas of Algeria was conducted. Results showed high variety in the botanical origin of samples and their physicochemical profile. Twenty-six samples were polyfloral honey, 30 were unifloral honey from different botanical sources such as Eucalyptus, Citrus, Apiaceae, Punica, Erica, Rosmarinus, Eriobotrya, or Hedysarum, and 6 were characterized as honeydew honey. Pollen analysis allowed the identification of 104 pollen types belonging to 51 botanical families, whereas the physicochemical profile showed important variations between samples. Multivariate techniques were used to compare the characteristics of samples from different biogeographical areas, showing significant differences between humid-area samples, located in the northeast of the country, and samples taken in semiarid, subhumid, and arid zones. Principal-component analysis (PCA) extracted nine components explaining 72% of data variance, being 30%, the sum of Component 1 and Component 2. The plot of both components showed samples grouped upon botanical and geographical origin. The results of this paper highlighted the great variability in honey production of Algeria, evidencing the importance of honey characterization to guarantee authenticity and to valorize local production.

Eucalyptus honey: Quality parameters, chemical composition and health-promoting properties

Eucalyptus honey is an important unifloral honey commercialized worldwide and much desired by consumers due to the medicinal properties attributed to it because of the plant from which it is produced. In general, eucalyptus honey has been classified as being rich in pollen grains from the eucalyptus tree as well as having physicochemical characteristics that, in a way, have made it stand out from other honeys. Similar to other types of honey, eucalyptus honey can suffer contaminations and adulterations that compromise its quality, safety and authenticity. Thus, detailed knowledge of the composition and properties of this monofloral honeys is of great importance. With this background, the aim of this review is to present and discuss recent data regarding the physicochemical characteristics, chemical and health-promoting properties of eucalyptus honey as well as microbial contamination, authenticity, processing and adulteration.

Honey Volatiles as a Fingerprint for Botanical Origin-A Review on their Occurrence on Monofloral Honeys

Honeys have specific organoleptic characteristics, with nutritional and health benefits, being highly appreciated by consumers, not only in food but also in the pharmaceutical and cosmetic industries. Honey composition varies between regions according to the surrounding flora, enabling its characterization by source or type. Monofloral honeys may reach higher market values than multifloral ones. Honey's aroma is very specific, resulting from the combination of volatile compounds present in low concentrations. The authentication of honey's complex matrix, according to its botanical and/or geographical origin, represents a challenge nowadays, due to the different sorts of adulteration that may occur, leading to the search for reliable marker compounds for the different monofloral honeys. The existing information on the volatiles of monofloral honeys is scarce and disperse. In this review, twenty monofloral honeys and honeydews, from acacia, buckwheat, chestnut, clover, cotton, dandelion, eucalyptus, fir tree, heather, lavender, lime tree, orange, pine, rape, raspberry, rhododendron, rosemary, strawberry tree, sunflower and thyme, were selected for volatile comparison purposes. Taking into consideration the country of origin, the technique of isolation and analysis, the five main volatiles from each of the honeys are compared. Whereas some compounds were found in several types of monofloral honey, and thus not considered good volatile markers, some monofloral honeys revealed characteristic volatile compounds independently of their provenance.

Honey: Chemical Composition, Stability and Authenticity

This Special Issue contains innovative research papers on the characterization, chemical composition and physical properties of honey. This constitutes very useful information to avoid frauds and to guarantee the authenticity of this food product. The knowledge of the particularities of honey is increasingly demanded by beekeepers and consumers, and also by labs to typify honeys according to their botanical origin and to check their quality. Melissopalynological, sensorial and physicochemical techniques are being used to study the characteristics of honeys samples from different plant sources and geographical areas. The combination of these analytical techniques with mathematical and statistical methods or chemometrics allows researchers to identify a set of variables or individual parameters that define independent samples, providing a practical solution to classify honey according to the geographical or the botanical origin.

Volatile Profile and Physico-Chemical Analysis of Acacia Honey for Geographical Origin and Nutritional Value Determination

Honey composition and color depend greatly on the botanical and geographical origin. Water content, water activity and color of 50 declared acacia samples, collected from three different geographical zones of Romania, together with chromatographic determination of sugar spectrum were analyzed. A number of 79 volatile compounds from the classes of: Alcohols, aldehydes, esters, ketones, sulphur compounds, aliphatic hydrocarbons, nitrogen compounds, carboxylic acids, aromatic acids and ethers were identified by solid-phase micro-extraction and gas-chromatography mass spectrometry. The overall volatile profile and sugar spectrum of the investigated honey samples allow the differentiation of geographical origin for the acacia honey samples subjected to analysis. The statistical models of the chromatic determination, physicochemical parameters and volatile profile was optimal to characterize the honey samples and group them into three geographical origins, even they belong to the same botanical origin.

Contribution to the Chromatic Characterization of Unifloral Honeys from Galicia (NW Spain)

Honey color and other physicochemical characteristics depend mainly on the botanical and geographical origin. The study of these properties could make easier a correct classification of unifloral honey. This work determined the palynological characteristics and some physicochemical properties such as pH, electrical conductivity, and color (Pfund scale and the CIELa*b* coordinates), as well as the total content of the bioactive compounds phenols and flavonoids of ninety-three honey samples. Samples were classified as chestnut, blackberry, heather, eucalyptus, and honeydew honey. The study showed a close relationship between the physicochemical variables and the botanical origin. The five types of honey presented different physicochemical properties among them. A principal component analysis showed that Hue, lightness, b*, and Chroma variables were important for the honey types classification, followed by Erica pollen, pH, Cytisus, and Castanea variables. A forward stepwise regression analysis was performed introducing as dependent variables the color (mm Pfund) and the Chroma and the Hue variables. The regression models obtained explained 86%, 74%, and 86% of the variance of the data, respectively. The combination of the chromatic and physicochemical and pollen variables through the use of multivariable methods was optimal to characterize and group the honey samples studied.