Sugar profiles and conductivity of stingless bee honeys from Venezuela
Sugar profiles and conductivity of stingless bee honeys from Venezuela
S Bogdanov 2
P Vit 2
0 Departamento Ciencia de los Alimentos, Facultad de Farmacia, Universidad de Los Andes , Mérida , Venezuela
1 Bee Department, Federal Dairy Research Station , 3097 Liebefeld, Bern , Switzerland
2 V K1ilchenmann
Summary — The HPLC sugar profiles and the conductivity of 42 stingless bee honey samples from Venezuela were determined. Three of the honey types were produced by Melipona species (n = 24), while the rest belonged mainly to five Trigona species. The main sugars of the Melipona honeys were fructose and glucose, with an average of 36.7 g/100 g. The Trigona (Frieseomelitta) honeys had a completely different sugar spectrum. There the principal sugar was a disaccharide with the retention time of maltose with an average content of 32.3 g/100 g, while fructose and glucose had smaller concentrations: 24.4 and 18.1 g/100 g respectively. The Melipona honeys contained also small quantities of maltose and only traces of oligosaccharides, while the Trigona honeys had small but measurable amounts of turanose, trehalose and erlose. The conductivity values of the Melipona honeys varied from 0.32 to 0.44 mS/cm and were significantly lower than those of the non-Melipona ones with minimum and maximum values of 1.04 and 1.07 mS/cm. honey / sugar / conductivity / HPLC / Meliponinae / Venezuela
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INTRODUCTION
The carbohydrates are the major
components of honey. The monosaccharides
fructose and glucose are the dominant fraction
and account for 85-95% of the honeybee
honey sugars, the remainder being
represented by a number of different di- and
trisaccharides (
Doner, 1977
; Bogdanov and
* Correspondence and reprints
The sugar composition of stingless bee
honeys has been studied occasionally.
Nogueira-Neto (1953)
,
Maurizio (1964)
and
Phadke (1968)
presented fructose, glucose
and sucrose values for few samples of
Melipona and Trigona honeys.
Roubik
(1983)
measured the sugar concentration
of honey in 86 colonies of 27 stingless bee
species from Panama, by refractometric Brix
units converted into gram equivalents.
Klink
(1992)
analysed enzymatically the glucose,
fructose and sucrose content of stingless
bee honeys from Costa Rica. Vit et al (1994)
compared the reducing sugar- and
apparent sucrose content of honeys from 40
colonies of nine stingless bee species from
Venezuela, using the Codex alimentarius
reducing sugar method. The pollen
spectrum of these honeys was also investigated
(Vit and Ricciardelli D’Albore, 1994)
.
The sugar profile and the conductivity
are those quality criteria, which are best
suitable for differentiating different sorts of
honey. In the present study we measured
the sugar content by HPLC and the
conductivity of 42 stingless bee honey samples
from Venezuela and discuss their role in
elucidating the entomological origin of
stingless bee honeys. However, we cannot
correlate our measurements to the floral origin
of the honeys, due to the very few
monofloral samples
(Vit and Ricciardelli D’Albore,
1994)
.
MATERIALS AND METHODS
Honey samples
Forty-two honey samples were extracted from
sealed honey pots of stingless bee (Apidae,
Meliponinae) hives located in different regions of
Venezuela during 1987-1988. Due to the
restricted number of honey samples from certain
species, we can only refer separately to three
Melipona: M compressipes compressipes, M
favosa favosa, M trinitatis and to one Trigona
species: Frieseomelitta aff varia. The other,
non-Melipona (mostly Trigona) species, have one
or two honey samples each and were grouped
together. For further details concerning the
honeys and their origin, see Vit et al, 1994.
Analysis
HPLC analysis was done according to
Bogdanov
and Baumann (1988)
: 10 μL of filtered 20% (g/vol)
honey solutions were directly injected on a 25 x
4.6 cm column filled with 3 mm Spherisorb-Amino
mounted on a HP 1084 chromatographic system
equipped with a Spectraphysics RI-detector 6040
with 80% acetonitrile as eluent. The temperature
of the column and the refractometer was 40 °C.
The following sugars were used as sugar
standards (g/100 mL): 4% fructose and glucose, and
0.5% each of sucrose, turanose, maltose,
trehalose, erlose, melezitose and raffinose. Except
for erlose (Senn Chemicals, Dielsdorf,
Switzerland), all sugars were purchased from Merck or
Fluka (Switzerland). The detecting limit of the
sugars is 0.1g/100 g honey.
Conductivity was measured on 20% (g/g by
dry weight) honey solutions at 20 °C
(Swiss food
manual, 1996)
and is expressed in millisiemens
(mS) per cm.
The statistical significance of the differences
between the various parameters of each honey
group was determined with Fischer’s
least-significant-difference test of a Systat software
package.
RESULTS
The results of our analysis are summarised
in table I, typical sugar profiles of the two
types of HPLC profiles honeys are shown
in figure 1.
The Melipona honeys had fructose and (...truncated)