A short review of headspace extraction and ultrasonic solvent extraction for honey volatiles fingerprinting

Honey volatiles exhibit a potential role in distinguishing honeys as a function of botanical origin, but heating of honey generates artefacts such as compounds of Strecker degradation and Maillard reaction products. This short review is focused on the most recently applied methods for honey volatiles fingerprinting (without generation of thermal artefacts): headspace extraction (dynamic headspace extraction (DHE), headspace solid-phase microextraction (HS-SPME)) and ultrasonic solvent extraction (USE). These methods display a varying degree of selectivity and effectiveness depending upon the compounds involved and the extraction conditions. Recent developments of these methods are discussed, with application examples drawn from the literature as well from our own research. Flavour qualities of the honey are very much dependent on the volatile and semivolatile organic compounds present in both the sample matrix and the headspace aroma. Therefore the use of one single technique is not adequate for reliable honey volatiles profiling, but combined use of headspace extraction and ultrasonic solvent extraction could be a useful tool for the characterization of the honey and identification of its botanical source through typical volatile marker compounds

Screening of Satureja subspicata Vis. honey by HPLC-DAD, GC-FID/MS and UV/VIS: prephenate derivatives as biomarkers

The samples of Satureja subspicata Vis. honey were confirmed to be unifloral by melissopalynological analysis with the characteristic pollen share from 36% to 71%. Bioprospecting of the samples was performed by HPLC-DAD, GC-FID/MS, and UV/VIS. Prephenate derivatives were shown to be dominant by the HPLC-DAD analysis, particularly phenylalanine (167.8 mg/kg) and methyl syringate (MSYR, 114.1 mg/kg), followed by tyrosine and benzoic acid. Higher amounts of MSYR (3-4 times) can be pointed out for distinguishing S. subspicata Vis. honey from other Satureja spp. honey types. GC-FID/MS analysis of ultrasonic solvent extracts of the samples revealed MSYR (46.68%, solvent pentane/Et2O 1:2 (v/v); 52.98%, solvent CH2Cl2) and minor abundance of other volatile prephenate derivatives, as well as higher aliphatic compounds characteristic of the comb environment. Two combined extracts (according to the solvents) of all samples were evaluated for their antioxidant properties by FRAP and DPPH assay; the combined extracts demonstrated higher activity (at lower concentrations) in comparison with the average honey sample. UV/VIS analysis of the samples was applied for determination of CIE Lab colour coordinates, total phenolics (425.38 mg GAE/kg), and antioxidant properties (4.26 mmol Fe2+/kg (FRAP assay) and 0.8 mmol TEAC/kg (DDPH assay)

GISAXS/GIXRD View of ZnO Films with Hierarchical Structural Elements

ZnO films constituted of porous sheet-like structures, formed by calcination of precursor, were examined using scanning electron microscopy and simultaneous small-angle scattering and diffraction of the synchrotron-sourced X-rays, under the grazing-incidence conditions. The presented analysis enabled insight into the complexity of the film morphology, which revealed substrate sensitivity on the microscopic and nanoscopic length scales. The average size and spatial arrangement of nanoparticles, single-crystal domains, and the average size and features of nanopores in sheet-like structures were determined for films deposited on glass, polycrystalline ZnO layer, and silicon

A short review of headspace extraction and ultrasonic solvent extraction for honey volatiles fingerprinting

Honey volatiles exhibit a potential role in distinguishing honeys as a function of botanical origin, but heating of honey generates artefacts such as compounds of Strecker degradation and Maillard reaction products. This short review is focused on the most recently applied methods for honey volatiles fingerprinting (without generation of thermal artefacts): headspace extraction (dynamic headspace extraction (DHE), headspace solid-phase microextraction (HS-SPME)) and ultrasonic solvent extraction (USE). These methods display a varying degree of selectivity and effectiveness depending upon the compounds involved and the extraction conditions. Recent developments of these methods are discussed, with application examples drawn from the literature as well from our own research. Flavour qualities of the honey are very much dependent on the volatile and semivolatile organic compounds present in both the sample matrix and the headspace aroma. Therefore the use of one single technique is not adequate for reliable honey volatiles profiling, but combined use of headspace extraction and ultrasonic solvent extraction could be a useful tool for the characterization of the honey and identification of its botanical source through typical volatile marker compounds

Biodiversity of Salix spp. honeydew and nectar honeys determined by RP-HPLC and evaluation of their antioxidant capacity

Rare unifloral willow (Salix spp.) honeys obtained from nectar or honeydew were investigated by direct RP-HPLC-DAD method in order to identify and quantify compounds that can be used as possible markers of their origin. Antioxidant and antiradical activities of willow honeys were evaluated using FRAP (=ferric reducing antioxidant assay) and DPPH (=1,1-diphenyl-2-picrylhydrazyl radical) tests, respectively. Also HMF (=5-(hydroxymethyl)furfural), diastase activity, and CIE L*a*b*C*h* chromatic coordinates were evaluated. Abscisic acids (ABA) are typical of willow nectar honey, with a predominance of (Z,E)-ABA on (E,E)-ABA (98.2 and 31.7mg/kg, resp.). Kinurenic acid and salicylic acid are useful to mark willow honeydew honey. The proposed HPLC-DAD method proved to be easy and reliable to identify the two different Salix spp. honeys, being not affected from any sample preparation artifact. Total antioxidant activity measured with the FRAP assay ranged from 3.2 to 12.6mmol Fe2+/kg, and the antiradical activity measured with the DPPH assay ranged from 0.6 to 3.0mmol TEAC (=Trolox equivalent antioxidant capacity)/kg in nectar and honeydew honeys, respectively. Salix spp. nectar and honeydew honeys proved to be two completely different honeys, because, besides color attributes, they show different antioxidant properties and specific compounds

Screening of Coffea spp. honey by different methodologies: theobromine and caffeine as chemical markers

Coffea spp. honey was screened by UV/VIS, HS-SPME/GC-MS/FID, USE/GC-MS/FID and HPLC-DAD. The direct HPLC-DAD methodology overcame the major limitations of the other methods used. The obtained results constitute a breakthrough since dominant xanthine derivatives were found (theobromine and caffeine with HPLC-DAD and caffeine by USE/GC-MS/FID). Phenylacetaldehyde was the major headspace compound

Croatian Agriculture Towards World Market Liberalization

Due to the limited domestic market and a loss of traditional markets, Croatian economic development today is based on export orientation with an important role of agriculture. Since 1990’s Croatian economy began transformation from communistic economy towards a liberal market economy. At the same time, Croatia intensified association processes to world and European trade organizations (WTO in 2000, free trade agreements with some European countries, signing Stabilization and Association Agreement - SAA in 2001 as well as beginning of EU accession negotiation process in 2005). Croatian agriculture experienced numerous transitional problems (mentioned loss of traditional markets, failures in privatizing state-owned land, poorly organized markets, technological and educational limitations, producer insolvency, an export-import deficit etc). The aim of this paper is to explore limitations of Croatian agriculture as well as possibilities that come along with associations to world and European organizations and associations

Comprehensive study of Mediterranean (Croatian) Propolis peculiarity: headspace, volatiles, anti-Varroa-treatment residue, phenolics, and antioxidant properties

Eight propolis samples from Croatia were analyzed in detail, to study the headspace, volatiles, anti-Varroa-treatment residue, phenolics, and antioxidant properties. The samples exhibited high qualitative/quantitative variability of the chemical profiles, total phenolic content (1,589.3-14,398.3 mg GAE (gallic acid equivalent)/l EtOH extract), and antioxidant activity (11.1-133.5 mmol Fe2+/l extract and 6.2-65.3 mmol TEAC (Trolox® equivalent antioxidant capacity)/l extract). The main phenolics quantified by HPLC-DAD at 280 and 360 nm were vanillin, p-coumaric acid, ferulic acid, chrysin, galangin, and caffeic acid phenethyl ester. The major compounds identified by headspace solid-phase microextraction (HS-SPME), simultaneous distillation extraction (SDE), and subsequent GC-FID and GC/MS analyses were α-eudesmol (up to 19.9%), β-eudesmol (up to 12.6%), γ-eudesmol (up to 10.5%), benzyl benzoate (up to 28.5%), and 4-vinyl-2-methoxyphenol (up to 18.1%). Vanillin was determined as minor constituent by SDE/GC-FID/MS and HPLC-DAD. The identified acaricide residue thymol was ca. three times more abundant by HS-SPME/GC-FID/MS than by SDE/GC-FID/MS and was not detected by HPLC-DA

Cornflower (Centaurea cyanus L.) honey quality parameters: chromatographic fingerprints, chemical biomarkers, antioxidant capacity and others

The samples of cornflower (Centaurea cyanus L.) honey from Poland were subjected to ultrasonic solvent extraction applying the mixture of pentane and diethyl ether 1:2 v/v (solvent A) as well as dichloromethane (solvent B). The major compounds of the extracts (analysed by GC–MS/GC–FID) were C13 and C9 norisoprenoids. Among them, (E)-3-oxo-retro-a-ionol (2.4–23.9% (solvent A); 3.9–14.4% (solvent B)) and (Z)-3-oxo-retro-a-ionol (3.7–29.9% (solvent A); 8.4–20.4% (solvent B)) were found to be useful as chemical biomarkers of this honey. Other abundant compounds were: methyl syringate (0.0–31.4% (solvent A); 0.0–25.4% (solvent B)) and 3-hydroxy-4-phenylbutan-2-one (1.6–15.8% (solvent A); 5.1–15.1% (solvent B)). HPLC–DAD analysis of the samples revealed lumichrome (4.7–10.0 mg/kg), riboflavin (1.9–2.7 mg/kg) and phenyllactic acid (112.1–250.5 mg/kg) as typical compounds for this honey type. Antioxidant and antiradical properties as well as total phenolic content of the samples were found to be rather moderate by FRAP (ferric reducing antioxidant power), DPPH (1,1-diphenyl-2-picrylhydrazyl radical) and Folin–Ciocalteu assays, respectively. Additionally, CIE L⁄a⁄b⁄C⁄h chromatic coordinates were evaluated. Colour attributes of cornflower honey were characterised by elevated values of L* and particularly high values of b* and h coordinates, which correspond to medium bright honey with intense yellow colour