Palynological, physico-chemical and organoleptic characteristics of carob tree (Ceratonia siliqua L.) honey from Sicily

Abstract

This study shows the results of melissopalynological and sensory evaluations on twenty-five carob tree
honey samples coming from Sicily and declared unifloral by the local beekeepers. This specific carob tree
honey production is erratic and limited because of its cold weather spreading, depending on seasonal
trends that influence both the final amount and quality of honey itself. According to the melissopalynological
results on samples, a minimum of 15% carob tree pollen was considered sufficient to typify these
honeys as unifloral. The physico-chemical analysis was performed on the samples satisfying this percentage and determined the following parameters: moisture, pH, acidity, HMF, diastase activity, electrical
conductivity, ash, sugar and colour. Physico-chemical analyses showed medium to high values for diastase
activity, electrical conductivity, free acidity and moisture.

Full text

Original article
Palynological, physico-chemical and organoleptic characteristics
of carob tree (Ceratonia siliqua L.) honey from Sicily
Giovanna Ferrauto* & Pietro Pavone
Section of Plant Biology, Department of Biological, Geological and Environmental Sciences, University of Catania, A. Longo 19, I-95125
Catania, Italy
(Received 4 December 2012; Accepted in revised form 9 February 2013)
Summary This study shows the results of melissopalynological and sensory evaluations on twenty-five carob tree
honey samples coming from Sicily and declared unifloral by the local beekeepers. This specific carob tree
honey production is erratic and limited because of its cold weather spreading, depending on seasonal
trends that influence both the final amount and quality of honey itself. According to the melissopalyno-
logical results on samples, a minimum of 15% carob tree pollen was considered sufficient to typify these
honeys as unifloral. The physico-chemical analysis was performed on the samples satisfying this percent-
age and determined the following parameters: moisture, pH, acidity, HMF, diastase activity, electrical
conductivity, ash, sugar and colour. Physico-chemical analyses showed medium to high values for diastase
activity, electrical conductivity, free acidity and moisture.
Keywords Ceratonia siliqua L., melissopalynology, physico-chemical properties, sensory analysis, Sicily, unifloral honey.
Introduction
In Sicily, the main honey productions are both unifl-
oral (Longhitano et al., 2007), like orange (Citrus sp.
pl.), eucalyptus (Eucalyptus sp. pl.), chestnut (Castanea
sativa), thyme (Thymus capitatus), sweet vetch
(Hedysarum coronarium) and multifloral. Among unifl-
oral types, carob tree honey is particularly important
for its peculiar characteristics. At the moment, accord-
ing to the available data, the production of carob tree
honey in Italy is well known in Sicily and particularly
in the Iblean territory (south-eastern Sicily), while for
the rest of the Mediterranean area, it is well known in
Turkey (Ricciardelli D’Albore & Vorwohl, 1979) and
Morocco (Terrab et al., 2003). Studies hitherto con-
ducted on this honey are few (Ricciardelli D’Albore &
Vorwohl, 1979; Terrab et al., 2003) and mostly con-
cerning foreign productions, whereas very little is
known about the one produced in Italy (Ricciardelli
D’Albore, 1997, 1998; Persano Oddo et al., 2000).
Usually a honey is considered unifloral if it is pro-
duced mainly by one plant and if the pollen frequency
of that plant in the honey sediments is >45% (Louve-
aux et al., 1978). There are, however, many exceptions.
There are honeys, in fact, whose dominant pollen can
be under-represented, like Citrus and Lavandula
(Ricciardelli D’Albore, 1997; Persano Oddo & Piro,
2004), or over-represented, like Eucalyptus and Casta-
nea (Ricciardelli D’Albore & Vorwohl, 1979; Fe
as
et al., 2010). For carob tree honey, however, there are
not at the moment official parameters to establish the
needed minimum percentage of pollen from Ceratonia
to classify this honey as unifloral. According to the
data reported by Ricciardelli D’Albore (1998), the
percentage would fluctuate around 30%, so these hon-
eys would all belong to Maurizio’s Class II (Maurizio,
1975), because in 10 g of honey, their total number of
plant constituents ranges between 20.000 and 90.000
ones.
This article shows therefore the results of a study
carried out on honey samples considered unifloral.
Melissopalynological, organoleptic and physico-chemi-
cal analyses were performed on the samples. Physico-
chemical analysis determined the following parameters:
moisture, pH, acidity, HMF, diastase activity, electri-
cal conductivity, ash, sugar and colour.
Materials and methods
Twenty-five samples of carob tree were collected in
total. The samples were declared unifloral by Sicilian
beekeepers and they were collected in the Iblean terri-
tory between 2006 and 2010. The samples, transferred
to glass containers of 250 g, were stored in constant
chamber at 4 °C in the melissopalynotheque of Section
of Plant Biology. Further 100 g of the honey samples
*Correspondent: E-mail: ggferra@unict.it
International Journal of Food Science and Technology 2013, 48, 1596–1602
doi:10.1111/ijfs.12129
©2013 The Authors. International Journal of Food Science and Technology ©2013 Institute of Food Science and Technology
1596

was stored in glass containers at a temperature
between 14 and 20 °C. This to allow the normal pro-
cess of crystallisation of honey also, otherwise inhib-
ited by temperature 4°C and 25 °C (Persano
Oddo et al., 1995; Tchoumboue et al., 2007).
Pollen analysis
The botanical origin of the collected samples was deter-
mined through qualitative melissopalynological
analysis. The qualitative analysis was performed on
twenty-five samples beginning from 10 g of honey using
the methods approved by the International Commission
for Bee Botany and described by Louveaux et al.
(1978). Sediments were acetolysed according to Erdt-
man’s (1960) method. Different pollen types were identi-
fied using De Leonardis et al. (1986a) pollen types key,
plus melissopalynological data sheets of the Sicilian
Apiarian Flora (De Leonardis et al.,1982,1984a,
b,1986b,1988,1992). A minimum of 700 pollen grains
was counted for sample. The results of the analysis were
expressed in percentages and divided into the following
frequency classes (Louveaux et al., 1978): dominant pol-
len >45%, accompanying pollen 16–45%, important
pollen 4–15% and minor pollen <3%.
Sensory analysis
Visual, olfactory and taste analyses were carried out
on twenty-five samples by an expert in honey sensory
analysis according to the method adopted by the
National Register Honey Sensory Experts (Persano
Oddo et al., 1995; Piana et al., 2004) and Gonnet &
Vache (1985).
Physico-chemical parameters
Physico-chemical analyses were performed on twelve
samples unifloral according to Official Method estab-
lished for Italy (Repubblica Italiana: DM, 2003DM
25/07/2003 - GURI n.185 of 11/08/2003), in agreement
with the European Directive (The Council of the Euro-
pean Union, 2002).
pH was determined with pH meter Mettler Toledo
SG2 from a solution of 10 g of honey, dissolved in
75 ml of CO
2
–free distilled water.
Free acidity and lactonic acidity were determined
according to the potentiometric method (White et al.,
1962): the addition of 0.05 MNaOH was stopped at
pH 8.5 (free acidity), immediately a volume of 10 ml
0.05 MNaOH was added, and without delay, back-
titrate with 0.05 N HCL to pH 8.3 (lactone acidity).
Total acidity was obtained adding lactones to free
acidity (AOAC, 1990).
Electrical conductivity was measured, at 20 °C, in a
20% (dry matter basis) solution of honey in CO
2
-free
deionised distilled water using Top Tronic model con-
ductimeter (Top Tronic, NA, Italy).
The values for ash content were obtained from the
measure of electrical conductivity according to the for-
mula (Piazza et al., 1991): X
1
=(X
2
–0.143)/1.743.
(where X
1
=ash % and X
2
=measure of electrical
conductivity millisiemens/cm
1
).
Moisture was measured with refractometer Bertuzzi
(Bertuzzi, MI, Italy) at 20 °C, using the Wedmore
table (Wedmore, 1955; AOAC, 1990).
Diastase activity was measured by spectrophotomet-
ric method (Bogdanov et al., 1997) with UV Vis Var-
ian 634-5 (CA, USA) using a kit Phadebas Amylase
Test (Pharmacy & Upjohn Diagnostic AB).
The method is based on the use of a substrate con-
sisting an insoluble blue-dyed cross-linked type of
starch. The enzymatic hydrolysis of this substrate
yields a blue water-soluble fragment spectrophotomet-
rically detectable at 620 nm. The absorbance of the
solution is directly proportional to the diastase activity
that is expressed in Schade units. A Schade unit con-
sists of the enzymatic activity of 1 g of honey that
converts 0.01 g of starch in 1 h at 40 °C.
Hydroxymethylfurfural (HMF) was determined by
HPLC method (Jeuring & Kuppers, 1980; Fallico
et al., 2004): 10 g of honey samples was diluted up to
50 ml with distilled water, filtered on 0.45-mm filter
and injected in a HPLC (Varian 9012Q, CA, USA)
equipped with a UV/Vis detector (Dynamax UV-DII
Rainin, Rainin Instrument, CA, USA) and column
150 mm 94.6 mm (15VE181E2J Knauer, Berlin, Ger-
many) with Eurospher II 100-5 C18. HMF is deter-
mined on a reversed-phase HPLC column by isocratic
elution with aqueous methanol as mobile phase. The
column temperature during the analysis was 18–25 °C;
the chromatograms were monitored at 285 nm. The
signal obtained was compared with that of the stan-
dard HMF (P99% Sigma-Aldrich, Milan), which
had a concentration range of 2.6 - 10 ml/l. The
amount of HMF was determined using an external cal-
ibration curve, measuring the signal at k285 nm.
Sugar composition (glucose, fructose and sucrose)
was determined according to Bogdanov et al. (1997) by
HPLC equipped with pump (Varian 9012Q), refractive
index (RI) detector (Rainin Dynamax RI-1, Rainin
Instrument, CA, USA) and column (250 mm 9
4.6 mm I.D.) with Licrospher 5 lm: 5 g of honey sam-
ples was diluted up to 40 ml with distilled water, imme-
diately, it was diluted to volume with acetonitrile, and
the final solution was filtered on 0.45-mm filter and
injected in a HPLC. The column and the RI detector
were maintained at 30 °C. The peak obtained was com-
pared with those of standard solution of sugars.
Colour was measured with Lovibond Comparator
2000 (USA). About 20 g of liquid honey was loaded
into test tube and the colour compared with those of
©2013 The Authors
International Journal of Food Science and Technology ©2013 Institute of Food Science and Technology
International Journal of Food Science and Technology 2013
Pollen physicochemical study carob tree honey G. Ferrauto and P. Pavone 1597

reference. Results were expressed according to Pfund
scale.
Results
Melissopalynological analysis
According to the results of the pollen analysis
performed on the twenty-five honey samples of carob
tree that beekeepers declared unifloral, only twelve were
considered unifloral. The qualitative analysis (Table S1)
showed that the percentage of Ceratonia is between
1.9% and 45%. Thirteen of the twenty-five samples
(numbered from 13 to 25) presented a rather low per-
centage of Ceratonia, between 3% and 7%. We have
considered these as multifloral with a high prevalence of
Cruciferae and so they were excluded from the physico-
chemical analysis. The remaining twelve samples
showed a percentage of Ceratonia average between
17.6% and 45%, and only these were considered as
unifloral, also for their organoleptic characteristics that
turned out to be more typical. Currently, the minimum
pollen percentage of Ceratonia, to classify as unifloral
this honey, is not yet established. Therefore, this study
establishes in 15% the minimum Ceratonia pollen per-
centage to classify them as unifloral, according to the
data reported by Ricciardelli D’Albore (1997); Ricciard-
elli D’Albore & Persano Oddo (1981).
In fact he points out that in these honeys, the
percentage of pollen grains is around 30% and more
rarely >45%; this could be probably due to the fact
that being Ceratonia siliqua a dioecious species mainly,
the amount of pollen available to bees could be
affected by this condition.
From the obtained data by the qualitative analysis,
it was elaborated a pollen spectrum (Fig. 1) of the
twelve samples examined (Aronne & De Micco, 2010).
The main pollen types occurring in no less than 20%
of the honey samples are reported according to their
frequency: dominant pollen >45%, accompanying pol-
len 16–45%, important pollen 4–15% and minor pol-
len <3%. Ceratonia siliqua is present as dominant
pollen (>45%) in only one sample, whereas in the
remaining samples, it is present as accompanying pol-
len (16–45%) together with Brassica type. Among pol-
len types that are present with the same frequency as
important pollen (4–15%) there are Carduus type,
Cerinthe major,Citrus type, Hedera helix,Teucrium
type, Lotus type, Asparagus type, Linaria type, Thymus
type, Eucalyptus type, Dorycnium type, Rosaceae type,
Allium type, Cistus incanus,Reseda type, Antirrhynum
type.
The most typical association, that is the whole of
pollen types which are present in at least 80% of the
samples, is represented by Carduus type, Cerinthe
major,Citrus type, Brassica type, Teucrium type, Lotus
type, Linaria type, Eucalyptus type, Asparagus type,
Echium type, Dorycnium type, Hedera helix.
Sensory analysis
The sensory analysis performed on twenty-five samples
(Table 1) showed that only samples numbered from 1
to 12 present characteristics corresponding to the type,
and they form a very homogenous group. These hon-
eys have a brighter beige colour or dark beige colour,
sometimes orange-coloured, odour and aroma of med-
ium intensity, vegetal and celery odour, lightly toasted;
taste reminds of carob aroma. The remaining samples’
colours (numbered from 13 to 25) are mostly beige to
greyish or dark amber colour, odour and aroma of
medium intensity or intense, odour and similarity of
0 20 40 60 80 100
Salix type
Trifolium gr. repens type
Smyrnium type
Antirrhynum type
Asphodelus type
Erica type
Scabiosa type
Ailanthus altissima
Chenopod./Amarant. type
Rhamnus type
Eryngium type
Carthamus type
Melilotus type
Robinia pseudoacacia
Vicia/Lathyrus type
Cichorium type
Betula/Corylus type
Senecio type
Hedysarum coronarium
Centranthus type
Clinopodium type
Anthemis type
Calendula type
Quercus type
Lobularia type
Ononis type
Diplotaxis type
Conium type
Borago officinalis
Reseda type
Prunus type
Acacia type
Oxalis type
Cistus incanus type
Rhus type
Castanea sativa
Sideritis type
Allium type
Euphorbia type
Salvia type
Thymus capitatus
Trifolium gr. pratense type
Centaurea type jacea
Rosaceae type
Hedera helix
Dorycnium type
Echium type
Asparagus type
Eucalyptus type
Linaria type
Lotus type
Teucrium type
Brassica type
Ceratonia siliqua
Citrus type
Cerinthe major
Carduus type
% Samples
Pollen types
>45%
16% – 45%
15% – 4%
1% – 3%
<1%
Poaceae
Oleaceae
Figure 1 Pollen spectrum of the melissopalynological results
observed in twelve samples of Sicilian carob tree. Data show main
pollen types are occurring in no less than 20% of the honey samples
and their frequency class (dominant pollen >45%, accompanying
pollen 16–45%, 4–15% important pollen, <3% minor pollen).
©2013 The Authors
International Journal of Food Science and Technology ©2013 Institute of Food Science and Technology
International Journal of Food Science and Technology 2013
Pollen physicochemical study carob tree honey G. Ferrauto and P. Pavone1598

aroma: cabbage. All samples crystallise quickly usually
within 3–4 weeks of collection.
Physico-chemical parameters
Physico-chemical parameters (Table 2) allow not only
to determine honey quality, but also to characterise
and differentiate honey types according to the botani-
cal origin.
Hydroxymethylfurfural (HMF) and diastase activity
indicate the freshness of honey. In the twelve analysed
samples, diastase activity was 19.9 Shade units with
values ranging between 12.00 Shade units and 23.07
Shade units and medium HMF value was 8.3 mg kg
1
,
Table 1 Results of the sensory analysis of twenty-five honey samples
S.N.
Visual
assessment Physical characteristics
Olfactory
assessment Tasting assessment
Colour Crystallisation Odour
Intensity
of odour
Similarity
of odour Flavour Persistence
Intensity
of aroma
Similarity
of aroma
1–12 From darker to brighter
beige, with greyish
and orange-coloured
shades
Crystallises quickly in
creamy crystals
Vegetal/
toasted
Medium Celery Normally sweet
normally acid
Long Medium Carob
13 From beige to greyish Crystallises quickly in
very fine crystals (like
fondant)
Vegetal Intense Cabbage Mild sweet,
decidedly acid
Long Medium Turnip
14 Dark amber Crystallises quickly in
very fine crystals
(like fondant)
Winey Intense Marsala
wine
Mild sweet,
decidedly acid
Short Intense Marsala
wine
15 From beige to greyish Crystallises quickly in
very fine crystals
(like fondant)
Vegetal Intense Carob Normally sweet,
decidedly acid
Long Medium Carob
16 From beige to greyish Crystallises quickly in
very fine crystals
(like fondant)
Vegetal Intense Cabbage Mild sweet,
decidedly acid
Long Medium Cabbage
17 Beige Crystallises quickly in
very fine crystals
(like fondant)
Vegetal Intense Cabbage Normally sweet,
normally acid
Long Medium Cabbage
18 From beige to greyish Crystallises quickly in
very fine crystals
(like fondant)
Vegetal Intense Cabbage Normally sweet,
normally acid
Short Medium Cabbage
19 Dark amber Crystallises quickly in
very fine crystals
(like fondant)
Vegetal Medium Cabbage Normally sweet,
normally acid
Short Medium Cabbage
20 Dark brown Crystallises quickly in
very fine crystals
(like fondant)
Caramel,
sugar
cooked
Medium Mustard Mild sweet,
decidedly acid
Short Intense Caramel
21 From beige to greyish Crystallises quickly in
very fine crystals
(like fondant)
Vegetal Intense Cabbage Mild sweet,
decidedly acid
Long Medium Cabbage
22 From beige to greyish Crystallises quickly in
very fine crystals
(like fondant)
Vegetal Medium Cabbage Normally sweet,
normally acid
Short Medium Cabbage
23 From beige to greyish Crystallises quickly in
very fine crystals
(like fondant)
Vegetal Medium Cabbage Normally sweet,
normally acid
Short Medium Cabbage
24 From beige to greyish Crystallises quickly in
very fine crystals
(like fondant)
Vegetal Medium Cabbage Normally sweet,
normally acid
Short Medium Cabbage
25 From beige to greyish Crystallises quickly in
very fine crystals
(like fondant)
Vegetal Medium Cabbage Normally sweet,
normally acid
Short Medium Cabbage
S.N., sample number.
©2013 The Authors
International Journal of Food Science and Technology ©2013 Institute of Food Science and Technology
International Journal of Food Science and Technology 2013
Pollen physicochemical study carob tree honey G. Ferrauto and P. Pavone 1599

with values ranged from a minimum of 7.40 mg kg
1
to a maximum of 8.90 mg kg
1
. According to EC (The
Council of the European Union, 2002) requirements,
the diastase number must be >8 on Shade scale, and
maximum HMF content is 40 mg kg
1
. The diastase
and HMF values founded in these honeys showed
lower values than the ones those reported by Terrab
et al. (2003) for carob tree honeys. In fact, in this
study, the diastase activity founded was of 26.5 °Gothe
and HMF of 22 mg kg
1
.
Another important parameter for honey preserva-
tion capacity is water content (moisture): honeys with
high moisture values incur fermentation. Current EC
requirements demand 20% moisture as maximum
limit; even if in high-quality honeys, moisture should
not be more than 18%.
In the analysed samples, moisture was 19.8%, that
is within the limits, but rather high, considering that
some samples presented values >20%. The average
moisture varied from 17.00% to 22.50% and showed
higher values than the ones reported by Terrab et al.
(2003) (18.3–19.3%).
Acidity is another important parameter for honey
quality, and it varies according to the botanical origin.
There are honeys, in fact, whose acidity is naturally
high. EC requirements require free acidity below
50 meq kg
1
. Within the analysed honeys, free acidity
was 30.51 meq kg
1
with values ranging between
23.41 meq kg
1
and 39.81 meq kg
1
; total acidity
33.05 meq kg
1
with values ranging between 25.94
and 41.96 meq kg
1
; lactonic acidity 2.54 meq kg
1
with values ranging between 1.86 meq kg
1
and
3.46 meq kg
1
and pH was 4.02 with values ranging
between 3.40 and 4.45. Electrical conductivity shows
the presence of mineral substances, organic acids, pro-
teins, etc. The presence and the percentage of these
substances in honeys are generally low and rather
varying, depending on floral origin. In the samples,
electrical conductivity was 0.63 mS cm
1
with a range
of 0.22–0.70 mS cm
1
.
The ash content is a quality criterion for honey
botanical origin. According to EC, the blossom honeys
have lower ash content than honeydew honeys. For
this parameter, EC prescribes a maximum limit of
0.6% for nectar honeys and a maximum limit of 1%
for honeydew honeys.
Ash content calculated by the electrical conductivity
varied from 0.046% to 0.66%, the mean value was
0.28%, as expected for nectar honeys.
The values of pH, ash and electrical conductivity
are agreed with data showed by Terrab et al. (2003)
(pH, 3.61; ash, 0.20%; electrical conductivity, 0.679
mS cm
1
). Instead, the observed values for the free
acidity and the total acidity are relatively high compar-
ing to the ones reported in Terrab et al. (2003) (free
acidity, 18.0 meq kg
1
; total acidity, 28.8 meq kg
1
).
Sugar content was represented mainly by fructose,
with a range of 36.92–42.56% (mean value, 40.29%),
and glucose, with a range of 24.15–32.29% (mean
value, 30.27%); sucrose was detected only in two sam-
ples with value of 0.24% and 0.22%, according to EC
requirements which demand values >5%.
As for the colour, these honeys present a medium
value of 82 mm on Pfund scale with values ranged
between 70 mm and 99 mm (Pfund scale) and are
within the category of light Amber honeys.
Discussion
Ceratonia siliqua is a polygamous or dioecious species,
of evergreen shrubs or trees, distributed in the south-
ern Mediterranean region, in maquis or garrigue habi-
tats. In Sicily, this species is widespread within the
upper thermo-mediterranean bioclimatic belt (Brullo
et al., 1996), which is characterised by medium
temperatures ranging from 16 to 18 °C and rainfall
between 400 and 600 mm of rain, concentrated in
autumn and winter time. This taxon is founded basi-
cally along the southern coast strip and particularly
within the south-eastern hilly belt of the Iblean terri-
tory, where it is widely cultivated.
Ceratonia is a good nectariferous species and blos-
soms in winter time. Therefore, because of seasonal
problems, carob tree honey production results to be
inconstant and often even unsuccessful.
As pollen spectrum of honeys is ‘the synthesis of the
flora in a territory’, it has been possible through the
spectrum to point out some pollen types that, although
sometimes present with low frequency, allow to outline
the habitat where that honey was produced. Among
Table 2 Physico-chemical parameters of twelve Carob tree honey.
Hydroxymethylfurfural (HMF)
Parameters Mean
Range
(Min. –Max.) S.d.
Colour (mm Pfund) 82 70–99 8.43
Ash content (%) 0.28 0.10–0.67 0.18
Diastase (Schade units) 19.93 12.00–23.07 2.81
Electrical conductivity (mS cm
–1
) 0.63 0.22–1.30 0.32
pH 4.02 3.40–4.45 0.34
Total acidity (meq kg
–1)
33.05 25.94–41.96 6.58
Free acidity (meq kg
–1)
30.51 23.41–39.81 6.42
Lactonic acidity (meq kg
–1)
2.54 1.86–3.46 0.50
Moisture (%) 19.80 17.00–22.50 1.61
HMF (mg kg
–1)
8.30 7.40–8.90 0.50
Glucose (%) 30.28 24.15–32.28 2.45
Fructose (%) 40.29 36.92–41.60 1.50
Sucrose (%) 0.04 0.0–0.24 0.08
Fructose +Glucose 70.57 62.20–72.97 3.64
Fructose/Glucose 1.34 1.24–1.42 0.09
s.d., standard deviation.
©2013 The Authors
International Journal of Food Science and Technology ©2013 Institute of Food Science and Technology
International Journal of Food Science and Technology 2013
Pollen physicochemical study carob tree honey G. Ferrauto and P. Pavone1600

pollen types, there are Teucrium type, Euphorbia type,
Asparagus type, Rosaceae type, Salvia type, Erica type,
Rhus type, Oleaceae type, Rhamnus type and Genista
type, all typical in maquis and garrigue habitats. There
are as well pollen types, which highlight aspects con-
nected to cultivated and ruderal anthropic environments
(Tomaselli et al., 1999; Ferrauto et al., 2004), as for
example: Citrus type, Brassica type, Echium type, Oxalis
type, Borago officinalis,Lobularia type, Cichorium type,
Vicia/Lathyrus type, Melilotus type, Chenopodium/Ama-
ranthus type, Eryngium type, Alkanna tintoria,Ferula
type, Poaceae and Urtica/Parietaria type.
According to these data, carob tree honey pro-
duced in Sicily would be different from the ones pro-
duced in Morocco and Turkey. Sicilian carob tree
honey would be different from Moroccan ones
(Terrab et al., 2003) for the absence of Arctotheca
calendula and the presence of Brassica type, Carduus
type, Cerinthe type, Hedera helix,Teucrium type,
Lotus type, Linaria type, Eucalyptus type and Aspara-
gus type. From the Turkish ones, it would differenti-
ate for the absence of Papaver. Moreover, Sicilian
honey would be different from Moroccan ones not
only for its accompanying species in the pollen
spectrum, but also for the percentage of pollen of
Ceratonia siliqua: this percentage in the Moroccan
samples is so high (64–66%) to make it possible to
determine a minimum limit of 45% of carob tree pol-
len to classify this honey as unifloral.
In Sicilian honeys, instead, at least up to now, the
percentage of pollen of Ceratonia siliqua generally
presents lower values. This clear-cut difference could
be due to various factors, for example the different
climatic characteristics between Morocco and Sicily
that would interfere in bees’ activity and in pollen
runoff because of the rains. Above all that, the kind
of stationary or nomadic beekeeping practice, the
process of honey extraction from supers or from brood
combs and the environment of production itself could
also affect in the quantity of pollen present in the sedi-
ment of the honey. As we are talking of a primarily
dioecious species, the main diffusion and abundance of
male individuals could influence the percentage of pol-
len in the sediment. In Sicily and particularly in the Ib-
lean territory, natural formations of maquis with
Ceratonia siliqua are rare because of the strong anthrop-
isation in these habitats. Carob trees are essentially cul-
tivated and are represented mostly by female
individuals for commercial reasons. This could further-
more explain the lower percentage of pollen of Cerato-
nia in the sediment of honeys.
Beyond melissopalynological aspects, Sicilian carob
tree honeys are characterised by particular physico-
chemical values. In particular, medium-
to-high diastase values, electrical conductivity and
total acidity are worth mentioning. Also moisture is
high as the period of production and extraction is
autumn time. In Sicily and in the Iblean territory, in
fact, autumn and winter are the periods with the high-
est precipitation rate. Consequently, this kind of honey
could be compared to Arbutus unedo honey, produced
in winter time, and to Calluna honey: both are charac-
terised by so high moisture values that CE require-
ments have been lifted to a maximum of 23%.
Conclusions
This work represents a preliminary study on Italian
carob tree honeys. According to the data obtained
from the performed analyses, various parameters,
which have been pointed out, allow us to differentiate
geographically these honeys from the ones produced in
the rest of the Mediterranean region.
Differences do not concern only the presence/
absence of some species in the pollen spectrum, but
also the percentage of pollen of Ceratonia siliqua, that
in Sicilian honeys is generally rather low (around
35%) (Ricciardelli D’Albore, 1997, 1998). The
variability of this element would depend on different
factors, among which the greater/sheerer abundance of
male individuals and the ways of honey extraction. In
Italy, honey extraction from brood combs for human
alimentation is nowadays an unusual practice and gen-
erally is left to the bees for their own use. Moreover,
this honey contains a great quantity of pollen, which
is stored by bees inside the brood chamber as a pri-
mary food source. Consequently, honey extracted from
these brood combs is richer in pollen than the one
extracted from supers. Therefore, a careful analysis of
all the factors that influence the final characteristics of
the product is necessary to characterise this honey.
Acknowledgments
The authors would like to thank Dr D. Pulvirenti for
the chemical analyses he carried out and Ms A. Speci-
ale for the translation of this work in English.
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Supporting Information
Additional Supporting Information may be found in
the online version of this article:
Table S1. Results of the qualitative analysis on
twenty-five honey samples, represented as percentages
©2013 The Authors
International Journal of Food Science and Technology ©2013 Institute of Food Science and Technology
International Journal of Food Science and Technology 2013
Pollen physicochemical study carob tree honey G. Ferrauto and P. Pavone1602