Page 4 - Aboud_etal2011

Characterization of Sicilian honeys
and magnetically stirred for 20 min at 40°C to allow equilibrium.
Then, the SPME fiber was inserted through the septum and exposed
to the vapor phase above the sample for 30 min. The fiber was then
retracted and introduced on the GC injector and held for 3 minutes
to allow the desorption of the analytes onto the column. Analysis of
organic volatile compounds was carried out using a gas-
chromatograph and mass-spectrometer (GC-MS) system (Hewlett-
Packard 5890 and 5973 MS). The column used was a HP5–MS (5%
diphenyl- 95% dimetil polisiloxano 30 m x 0.2 mm, 0.25 μm film,
J&W Scientific, Folsom CA, USA). The oven temperature was
maintained at 40°C for 5 min, then raised 5°C/min to 280°C and
held for 10 min. Helium was used as carrier gas with a flow rate of 1
mL min; injection mode was splitless. The injection port temperature
was 280oC.
MS full-scan method was used and the electron impact
ionization spectra were obtained at 70 eV, recording mass spectra
from m/z 42 to 550 UMA. The compounds’ mass spectra were
compared with those of data bank MS NIST 05 and the
identifications were confirmed by using standard products (all 99%
purity – Fluka, Sigma-Aldrich Chemie GmbH, Switzerland). Blank
samples were run after conditioning the fiber at the manufacture’s
recommended temperature in order to characterize possible
contaminants from the fiber or chromatographic system.
Results
Pollen identification
The pollen grains from all the samples were investigated
microscopically. Twenty four honeys were considered to be
monofloral, four were multifloral, and one was a honeydew honey
(Table 1). The percentages of the most abundant pollen types in
each honey sample, as well as the nectar and pollen character of
these plants were taken into account. Following the criteria of
Zander (1950), when the percentage of the most abundant pollen
type was over 45%, the honey sample was classified as unifloral,
with an exception of eucalyptus pollen at 70%. Lower percentages
were classified as polyfloral.
Eucalyptus camaldulensis was the predominant pollen type
presented in 4 honey samples (H17, H27, H28 and H29), whereas
other species like E. globules and E. viminalis were also presented.
These species grow in many countries of the Mediterranean region,
and are generally defined as eucalyptus. The botanical identification characterize a unifloral honey. This is in accord with European
of this kind of honey is rather easy, because its pollen is
overrepresented in the spectra, reaching more than 90%, with a
content of more than 100,000 pollen grains per 10 g of honey.
Pollen analysis may extend the identification of other particles in
honey than of pollen, e.g. eucalyptus honey sample (H17) showed
the presence of honeydew elements such as fungal spores and
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mycelium. Hedysarum coronarium L. (Sulla) was the second most
abundant pollen type identified, being the dominant pollen in 6
honey samples (H4, H9, H12, H16, H19 and H22) at more than 45%.
This source is largely used by honeybees in Sicily. It is an important
nectariferous plant belonging to the Leguminosea family, which is
abundant throughout the world, comprising of more than 10,000
species. Sulla honey is produced in Italy in large amounts and there
are 408 species grouped in 58 genera. The quantitative and
qualitative value of the pollen prevalent in this honey is normally
represented with a 2000-9000 pollen grains / g. Honey sample H19
was also contaminated by some honey elements like the sample H17.
Ericaceae are important melliferous plants in the Mediterranean
area (Terrab et al., 2003 a and b). In Italian honeys this family is
represented by 10 genera and 24 species (Ricciardelli and Oddo,
1981). The pollen of Erica arborea was predominant in samples H14
and H18 and it was secondary in one sample (H15). Ericaceae family
has a substantial interest for bees and many genera are assiduously
visited by bees for pollen and nectar. This pollen is underrepresented
because of the large size of the granule. Also the flowers are curved
backwards which means that they are not contaminated by other
pollens, making it a good source for monofloral honey.
Rutaceae family, commonly known as the citrus family, is
represented in Italy by 14 species, subdivided in 4 genera: Ruta,
Dictamnus, Haplophyllum and Citrus. The most economically
important is Citrus, which includes the orange (C. sinensis), lemon
(C. limon), grapefruit (C. paradise), and lime (C. aurantifolia). The
Citrus aurantium represents the predominance in honey production.
Citrus pollen is generally under-represented in citrus honey (Maurizio,
1949, 1958; Vorwohl, 1973) and the results confirm that one sample
(H20) from Palermo (Termini Imerese) was low in pollen content.
Also, an essential characteristic of this kind of honey pollen is the
presence of some indices of honeydew honey: spores, microscopic
green algae, fragments of mycelium, and frequently the presence of
starch grains. Two samples were listed as thyme honey (H6, H25)
from Palermo (Termini Imerese) and Trapani (Favignana)
respectively. Absolute counts for thyme pollen varied from 3700 to
9100 /g in the purest samples examined (H6, H25). On this basis
thyme pollen was under-represented in the samples and it was
calculated that a minimum of 20% thyme pollen was required to
experience (Maurizio and Louveaux, 1965; Maurizio, 1975). Castanea
sativa Miller (chestnut) pollen was over-represented in the samples
(H5 and H13); the percentage of pollen in the sediment was higher
than 90%. Also here, sample H5 demonstrated the existence of some
honeydew elements, as a result of attacks by Myzocallis castanicola
insect. Chestnut is often visited for its yellow pollen. The botanical
and geographical origin of all the honey samples are summarized in
Table 1.