Evaluation of four isolation techniques for honey aroma compounds

The analysis of the volatile fraction of honey provides useful information for the determination of the botanical and geographical origin. However, the results obtained vary greatly upon the extraction procedure employed. Four different isolation techniques were compared, that is hydrodistillation (HD), micro‐simultaneous steam distillation–solvent extraction (MSDE), ultrasound‐assisted extraction (USE) and solid‐phase microextraction (SPME). From the data obtained, USE and SPME seem to be more suitable for the isolation of potent marker compounds. HD and MSDE have main drawbacks because of the drastic conditions used that lead to the formation of artefacts and the degradation of sensitive compounds. These drawbacks are avoided when employing USE and SPME. Copyright © 2004 Society of Chemical Industry     

Rapid determination of safranal in the quality control of saffron spice (Crocus sativus L.)

A method to determine safranal content based on non-polar solvent extraction followed by UV–Vis analysis available in the industry for quality control of saffron spice has been studied. Ultrasound-assisted extraction of safranal was carried out and optimised with respect to the solvent: diethyl ether, hexane and chloroform; the time of extraction; and the concentration of saffron in each organic solvent. Best extraction conditions were obtained when 20 g L^?1 of saffron was extracted with chloroform for 15 min. Intra-laboratory validation of the optimised conditions and analysis by UV–Vis spectrophotometry showed satisfactory results in linearity, repeatability, intermediate precision and recovery. The limit of detection was 1 mg safranal kg^?1 saffron and the limit of quantification was 3 mg safranal kg^?1 saffron.     

The in vitro antioxidant and antimicrobial activities of the essential oil and various extracts of Origanum syriacum L var bevanii

The present work examines the in vitro antioxidant and antimicrobial properties of the essential oil and various extracts from the herbal parts of Origanum syriacum L var bevanii. Polar subfractions of methanol extracts from both deodorised and non‐deodorised materials showed the highest DPPH (2,2‐diphenyl‐l‐picrylhydrazyl) radical‐scavenging activity, with IC₅₀ values of 21.40 and 26.98 µg ml^?1 respectively, whereas the IC₅₀ of the essential oil was 134.00 µg ml^?1. The antioxidant potential of the extracts appeared to be closely related to the presence of polar phenolics. However, the inhibitive effect on linoleic acid oxidation might be promoted by the presence of non‐polar phenolics, as both hexane and dichloromethane extracts showed high antioxidant activities. The antimicrobial activity of the essential oil was superior to those of the other extracts. Nineteen compounds representing 962 g kg^?1 of the essential oil were identified; carvacrol (669 g kg^?1) was the main component. Overall, the results suggest that the essential oil and extracts from the herbal parts of O syriacum could be used as natural preservative ingredients in the food industry. Copyright © 2004 Society of Chemical Industry     

Milk β-lactoglobulin complexes with tea polyphenols

The effect of milk on the antioxidant capacity of tea polyphenols is not fully understood. The complexation of tea polyphenols with milk proteins can alter the antioxidant activity of tea compounds and the protein secondary structure. This study was designed to examine the interaction of β-lactogolobulin (β-LG) with tea polyphenols (+)-catechin (C), (−)-epicatechin (EC), (−)-epicatechin gallate (ECG) and (−)-epigallocatechin gallate (EGCG) at molecular level, using FTIR, CD and fluorescence spectroscopic methods as well as molecular modelling. The polyphenol binding mode, the binding constant and the effects of polyphenol complexation on β-LG stability and secondary structure were determined. Structural analysis showed that polyphenols bind β-LG via both hydrophilic and hydrophobic interactions with overall binding constants of K_C–β-LG = 2.2 (±0.8) × 10³ M⁻¹, K_EC–β-LG = 3.2 (±1) × 10³ M⁻¹, K_ECG–β-LG = 1.1 (±0.6) × 10⁴ M⁻¹ and K_EGCG–β-LG = 1.3 (±0.8) × 10⁴ M⁻¹. The number of polyphenols bound per protein molecule (n) was 1.1 (C), 0.9 (EC), 0.9 (ECG) and 1.3 (EGCG). Molecular modelling showed the participation of several amino acid residues in polyphenol–protein complexation with extended H-bonding network. The β-LG conformation was altered in the presence of polyphenols with an increase in β-sheet and α-helix suggesting protein structural stabilisation. These data can be used to explain the mechanism by which the antioxidant activity of tea compounds is affected by the addition of milk.     

The effect of salinity on the growth,yield and essential oils of turnip‐rooted and leaf parsley cultivated within the Mediterranean region

BACKGROUND: Turnip‐rooted parsley, a field‐crop of northern Europe, has recently been introduced to the Mediterranean region for fresh consumption or production of essential oil. Because of soil salinity within this area, the sensitivity of turnip‐rooted and two other parsley subspecies (plain‐ and curly‐leafed) to salt was studied. RESULTS: NaCl or CaCl₂ additions to the irrigation water raised the electrical conductivity (EC) in increments from 0.5 dS m^?1 to 4.5 dS m^?1 (year 1) or 6.0 dS m^?1 (year 2), reducing parsley foliage weight in year 2, but increasing the root weight of turnip‐rooted parsley in year 1. Raising the EC with NaCl increased the yield of foliar essential oil from curly‐leafed parsley (both years), but not from the other cultivars. CaCl₂ had less effect on oil yield. The relative concentrations of the principal aroma constituents (β‐phellandrene, myristicin, β‐myrcene and apiole) of the foliar essential oil were affected by NaCl or CaCl₂ in a way that differed between cultivars. Oil yield from parsley roots was very low and apparently unaffected by salinity. CONCLUSION: All three parsley subspecies are moderately sensitive to salinity, but may be cultivated at <4.5 dS m^?1 EC. Salinity may assist oil production by increasing oil yield (curly‐leafed parsley) and positively affecting certain aroma constituents. Copyright © 2009 Society of Chemical Industry     

Solid-phase microextraction/gas-chromatographic/mass spectrometric analysis of p-dichlorobenzene and naphthalene in honey

Protection of honeycombs from the Wax moth, Galleria mellonella, involves the use of physical, biological or chemical control methods. As chemical control may result in residues in the extracted honey, the presence of p-dichlorobenzene and naphthalene residues was investigated by solid-phase microextraction (SPME) coupled to gas-chromatographic/mass spectrometry (GC/MS). The method was linear between 5 and 200 microg kg(-1) honey for p-dichlorobenzene and 1 and 200 microg kg(-1) for naphthalene. Limits of detection were 1 and 0.1 microg kg(-1), respectively, for p-dichlorobenzene and naphthalene, while relative standard deviations were 2.6 and 7.9%, respectively. Application of the method to 90 unifloral Greek honeys revealed that, in 25.6% of the samples, the concentration of either one of the pesticides exceeded the maximum residue level (MRL). Maximum concentrations were 163.03 microg kg(-1) honey for p-dichlorobenzene and 193.74 microg kg(-1) honey for naphthalene. Naphthalene was found in traceable amounts in 78.9% of the samples, but only 5.6% of them contained concentrations above the MRL, which indicates the use of pre-contaminated honeycomb foundations or built combs. Nevertheless, because naphthalene is naturally present in some plant species growing in Greece, the contribution of nectar from such a floral source should not be overlooked.     

Flavour compounds of Greek cotton honey

Finding marker compounds is a powerful tool in the determination of the botanical origin of honey. For this purpose the flavour fraction of Greek cotton honey was investigated. A striking characteristic of this type of honey is the presence of more than 35 phenolic compounds in the extract, accounting for almost 60% of the total amount of compounds positively identified by gas chromatography/mass spectrometry. In comparison with honeys of nine different origins, a total of 15 compounds could serve as potent markers for cotton honey, namely cinnamaldehyde (0.44%), cinnamyl alcohol (1.79%), cinnamic acid (1.13%), neryl and geranyl nitrile (0.16 and 0.41% respectively), benzenepropanol (0.5%), homovanillyl alcohol (0.6%), (E)‐ and (Z)‐p‐methoxy‐cinnamic acid (0.48 and 0.14% respectively), 2‐methyl‐p‐phthalaldehyde (0.22%), coniferaldehyde (0.47%), p‐coumaric acid (1.77%), ferulic acid (0.51%), scopoletin and scoparone (0.47%). Copyright © 2005 Society of Chemical Industry     

Antimicrobial and antioxidant properties of the essential oils and methanol extract from Mentha longifolia L. ssp. longifolia

This study was designed to evaluate antimicrobial and antioxidant activities of the essential oil and methanol extract from Mentha longifolia ssp. longifolia. The essential oil showed strong antimicrobial activity against all 30 microorganisms tested whereas the methanol extract almost remained inactive. In contrast, the extract showed much better activity than the essential oil in antioxidant activity assays employed, e.g. in the inhibition of free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene/linoleic acid systems. In the former, the extract was able to reduce the stable free radical DPPH with an IC₅₀ of 57.4 μg/ml while that of the oils was 10 700 μg/ml. When compared to BHT, a synthetic antioxidant, both showed weaker antioxidative potential. Similarly, in β-carotene/linoleic acid assay, these samples were not effectively able to inhibit the linoleic acid oxidation; exhibiting only 24% and 36% inhibitions at 2 mg/ml, respectively; both were far below than that of BHT. Total phenolic constituent of the extract was 4.5 g/100 g as gallic acid equivalent. GC–MS analysis of the oil resulted in the identification of 45 constituents, cis-piperitone epoxide, pulegone and piperitenone oxide being the main components.     

Investigation of the antioxidant properties of Ferula orientalis L. using a suitable extraction procedure

The present work examines the in vitro antioxidant properties of the essential oil and various extracts prepared from the herbal parts of Ferula orientalis A. (Apiaceae). The highest 2,2-diphenyl-l-picrylhydrazyl (DPPH) radical-scavenging activity was found in the polar extract, e.g. methanol–water (1:1), obtained from non-deodorised materials with IC₅₀ values at 99.1 μg/ml. In the β-carotene/linoleic acid assay, the deodorised acetone extract exhibited stronger activity than the polar one. The relative antioxidant activities (RAA%) of the extracts ranged from 10.1% to 76.1%, respectively. Extraction with methanol–water (1:1) mixture was concluded to be the most appropriate method in terms of higher extract yield, as well as effectiveness, observed in both assays. Although the essential oil showed antioxidative potential, it was not as strong as that of positive control (BHT). GC/MS analysis of the essential oil resulted in the identification of 39 compounds, β-phellandrene (23.6%), (E)-β-ocimene (13.8%), α-pinene (12.5%), α-phellandrene (11.5%) and dehydro-sesquicineole (10.1%) being the major components.