Control of bean thrips in navel oranges using ethyl formate fumigation for export to Australia
Determining Effect of Ethyl Formate and Vapormate® on...
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Tunisian Journal of Plant Protection 51 Vol. 11, No. 1, 2016
Determining Effect of Ethyl Formate and Vapormate® on
Disinfestation Efficiency and Organoleptic Quality of Date
Fruits
Haithem Bessi and Cyrine Ferchichi, LR03AGR01-Laboratoire de Recherche
Economie, Sciences et Technologies Agroalimentaires, INAT, Université de
Carthage, Tunis, Tunisia, Sondes Yousfi, ISA-ChM, Université de Sousse, Sousse,
Tunisia, Flamini Guido, Dipartimento di Farmacia, via Bonanno 33, 56126 Pisa,
Italy, Manel Issaoui, LR12ES05, Laboratoire de Biochimie, Faculté de Médecine
de Monastir, Université de Monastir, Monastir, Tunisia, Veronique Bikoba and
Elizabeth J. Mitcham, Department of Plant Sciences, University of California,
Davis, CA95616, USA, Kaouthar Grissa, LR14AGR02-Laboratoire de Recherche
Bioagresseurs et Protection Intégrée en Agriculture, INAT, Université de Carthage,
Tunis, Tunisia, and Sihem Bellagha, LR03AGR01-Laboratoire de Recherche
Economie, Sciences et Technologies Agroalimentaires, INAT, Université de
Carthage, Tunis, Tunisia __________________________________________________________________________
ABSTRACT
Bessi, H., Ferchichi, C., Yousfi, S., Guido, F., Issaoui, M., Bikoba, V., Mitcham, E.J.,
Grissa, K., and Bellagha, S. 2016. Determining effect of ethyl formate and Vapormate®
on disinfestation efficiency and organoleptic quality of date fruits. Tunisian Journal of
Plant Protection 11: 51-62.
Perfectly integrated into the Tunisian economy, date sector is undergoing a great expansion in
production and exports. Infestation is a major problem encountered during the dates’ postharvest
period. Consequently, there is a need to maintain fruit quality during handling, packaging and storage.
Currently, after the methyl bromide (MB) restriction, the industry needs an efficient and
environmental-friendly alternative against insects. In this study, ethyl formate (EF) had been chosen to
fumigate dates of Deglet Nour variety. Initially, trials at laboratory scale were performed with the most
resistant larvae stage of the carob moth (Ectomyelois ceratoniae). For this purpose, three EF
concentrations (114.4, 127.8, and 143 g/m3) and two exposure durations (2 and 3 h) were tested.
Results revealed that the most efficient combination was 143 g/m3 of EF for 2 h, which caused 98.12%
mortality. Then, experiments were undertaken at a semi-industry scale with Vapormate®, the
commercial version of EF containing a combination of EF and CO2. The mortality rate was further
improved, reaching 100%. However, the CO2 synergistic effect was not demonstrated. In addition, the
effects of EF and Vapormate® on the quality of fumigated fruits regarding color, sugar content and
aromatic composition was assessed and discussed. No changes in fruit quality were observed after
fumigation.
Keywords: Carob moth, date quality, ethyl formate, fumigation, mortality rate, Vapormate®
_________________________________________________________________________
Corresponding author: Sondes Yousfi, Email: [email protected], Accepted for publication 7 March 2016
Tunisian Journal of Plant Protection 52 Vol. 11, No. 1, 2016
Dates are appreciated for their
organoleptic properties and their high
commercial value (1). Actually, Tunisia is
the first producer of dates and mainly
Deglet Nour variety. The production has
reached 192.125 tons in 2013 (15).
Therefore, date fruits and their
postharvest processing occupy an
important income for this country.
Nevertheless, dates are subjected to many
pests and diseases causing several
damages to the fruit making it unsuitable
for human consumption and unacceptable
for marketing. The carob moth,
Ectomyelois ceratoniae (Lepidoptera:
Pyralidae), is considered as the main pest
of dates; it develops inside the fruit and
continues its growth during storage (17,
30). Nowadays, industries moved away
from using the chemical fumigant, methyl
bromide (MB) for postharvest
disinfestation after its restriction of use by
the international Protocol of Montreal. In
addition, some pests developed a kind of
resistance to the phosphine (20).
Consequently, an efficient, safe and
unchangeable date quality alternative to
these fumigants is strongly recommended.
Moreover, ethyl formate (EF) is a
fumigant that proved its efficacy on a
large number of products against their
associated pests (21). For this, EF seems
to be an appropriate alternative to other
fumigants. Furthermore, Vincent and
Lindgren (30) showed that Plodia
interpunctella and Ephestia figulilella
were more sensitive to the EF than
Oryzaephilus surinamensis and
Carpophilus hemipterus. Likewise, it
demands a short exposure time and it is
classified as GRAS (Generally
Recognized As Safe) (29). EF advantages
include natural occurrence in food, rapid
kill of insects (within 2-4 h), fast
breakdown of residues in natural products
and low human toxicity (24). On the other
hand, unlike fruits mentioned above, EF
fumigation must be performed as an
absorption phenomenon when it is used
for dates. In fact, EF has to act inside the
fruit where the pest is localized (10). In
the industry scale, EF is commercialized
as a mixture of CO2 and EF: 16.7% EF +
83.3 CO2 (Vapormate®, LINDE Group).
The liquid carbon dioxide, considered as
a carrier gas and fire retardant, should
enhance the penetration of EF and
consequently improve disinfestation
efficiency. However, this synergistic
effect depends on the target pest species
and its development stage (13). Currently,
Vapormate® is used to fumigate cereal
grains and oilseeds stored into silos, as
well as horticulture products. Hence,
when employed at atmospheric pressure
for 24 h at a dose of 420g/m3, it provides
100% mortality of insect pests [Tribolium
castaneum and Rhizopertha dominica
attacking stored grains (8)]. The
objectives of this work were to
investigate the effectiveness of EF and
Vapormate® to eliminate the most
resistant stage of carob moth from dates
and to evaluate their ability to preserve
fruit quality. Moreover, the effect of date
treatment on color and the aroma volatile
composition of dates of the Deglet Nour
variety was studied.
MATERIALS AND METHODS Raw material.
Deglet Nour variety dates were
purchased from a local distributor and
stored at 4°C to maintain its quality.
Uniform and undamaged fruits were
selected and used for both disinfestation
trials and quality analyses.
Rearing conditions of carob moth.
The first larvae stage L1 of the
carob moth obtained from infested field-
collected pomegranates in Grombalia
(Tunisia), were placed into plastic boxes
Tunisian Journal of Plant Protection 53 Vol. 11, No. 1, 2016
containing an artificial diet based on
wheat bran, sucrose, yeast, vitamin C, salt
mixture, aureomycin, lysine,
methylparaben, glycerin, and distilled
water (18). These boxes were placed into
a rearing room: 27ºC, 70% relative
humidity and a photoperiod of 16:8 h
(L:D) (21). The boxes were controlled
daily. Hence, adults were collected and
placed into boxes covered with a filter
paper. Two days after oviposition, eggs
deposed on the filter paper were reared in
the culture medium until they reached the
required stage L5.
EF and Vapormate® trials.
In a previous study, it has been
demonstrated that the most resistant carob
moth stage is the fifth larvae stage, L5
(7). Therefore, trials were performed on
dates artificially infested with that
resistant stage to determine the
percentage of disinfestation and mortality
of the carob moth. In the laboratory scale,
previously infested dates were placed in a
1 L glass jar sealed with a rubber stopper
fitted with inlet and outlet tubing. Liquid
EF was injected through the rubber
stopper onto filter paper using a micro-
syringe, as described by Vincent and
Lindgren (30). Three EF concentrations
were tested: 114.4, 128.7, and 143.0 g/m3,
using two exposure times: 2 and 3 h (9).
Four replications with 410 g of dates per
individual treatment were used.
Concerning the semi-industry
trials, a fumigation pilot plant has been
designed by the LINDE Group technical
team. It consisted of a stainless steel
enclosure (capacity 100 l) with a sealed
cover connected to the bottle of
Vapormate® (16.7% EF + 83.3% CO2)
by a copper pipe (1 cm in diameter) fitted
with a manometer. A precision balance (±
0.005 kg) was used to determinate the
quantity of Vapormate® injected in the
enclosure. Semi-industrial treatments
were run with five replications. For each
one, three trays containing 50 pieces of
artificially infested dates were placed
respectively in the middle and the two
opposite corners of the enclosure. Then,
dates were added into the enclosure to
reach a total of 41 kg of fruits.
Fruit quality analyses.
Physicochemical analyses. In this
study, quality analysis has been
determined for EF and Vapormate®
treated dates with the optimum
fumigation treatment. The post-treatment
fruit physicochemical quality evaluations
included reducing sugar content, water
content, water activity and CIE Lab color.
The results were compared with those of
untreated control. Bernfeld (6)
colorimetric method was chosen to
determine the reducing sugar content by
means of a spectrophotometer. After
preparing a date solution with a final
concentration of 5 g/l, its absorbance
measured at 540 nm was converted into a
concentration using a standard curve.
Water activity was measured on 5 g of
crushed dates with an IC-500Aw-LAB
instrument. Water content was
determined by drying 5 g of fruit at
105°C for 48 h (NT 134 45-14).
Finally, CIE color parameters L*,
a* and b* were measured for the same
whole piece of dates twice (external and
internal faces) before and after fumigation
with EF and Vapormate®. All these
analyses were realized the same day of
disinfestation both with EF and
Vapormate®, at room temperature. Three
replicates of 12 fruits were used for each
analysis and the final result was
expressed as mean of all the replicates.
Volatile compound analyses. Four
samples of dates were used: untreated
dates (control), dates treated with 114.4
g/m3
of EF, dates treated with 143 g/m3
of
Tunisian Journal of Plant Protection 54 Vol. 11, No. 1, 2016
EF and dates treated with 856 g/m3
of
Vapormate®. These selected
concentrations allowed an adequately and
completely control of the most resistant
stage of carob moth. All these analyses
were carried out after storage at 5°C for
one week. Supelco (Bellefonte, PA)
SPME devices coated with
polydimethylsiloxane (PDMS, 100 µm)
were used to sample the headspace of
fresh dates inserted into a 50 ml vial and
allowed to equilibrate for 30 min. Then,
the fiber was exposed to the headspace
for 50 min at room temperature. Once
sampling was finished, the fiber was
withdrawn into the needle and transferred
to the injection port of the GC-MS
system. GC-EIMS analyses were
performed with a Varian (Palo Alto, CA)
CP3800 gas chromatograph equipped
with a DB-5 capillary column (30 m ×
0.25 mm × 0.25 lm; Agilent) and a Varian
Saturn 2000 ion trap mass detector.
Operatory conditions were as
follow: injector and transfer line
temperatures were 250 and 240°C,
respectively; oven temperature was
programmed from 60 to 240°C at
3°C/min; carrier gas helium at 1 ml/min;
split less injection. Identification of the
constituents was based on comparison of
the retention times with those of authentic
samples, comparing their linear retention
indices (LRI) relative to a series of n-
hydrocarbons, and on computer matching
against commercial (2) and homemade
library of mass spectra, and MS literature
data (3, 27). Moreover, the molecular
weights of all the identified substances
were confirmed by GC-CIMS, using
methanol as ionizing gas.
Statistical analyses.
Data were subjected to one way
analysis of variance using Stat Graphics
Centurion XV (Stat Point Technologies,
Inc., Warrenton, VA) version 2010 and
Tukey’s test was applied to the means to
detect significant differences at the 0.05
percent level. EF and Vapormate® were
tested for their effects on carob moth
mortality depending on concentrations
and exposure times and on the quality of
fumigated dates as compared to control.
RESULTS Effect of ethyl formate on carob moth
mortality.
Disinfestation trials were initiated
with 4% of EF corresponding to 114.4
g/m3 during 2 h. The carob moth
mortality registered of the four trials was
91.6%. Subsequently, the EF
concentration injected was successively
increased 0.5% for each treatment, thus
4.5 and 5% EF were tested. Statistical
analyses showed that there is a significant
difference between these treatments and
that the EF concentration had a
significant effect on fumigation
efficiency. All EF-based treatments
resulted in significant carob moth
mortality and are represented in Table 1.
The highest mortality, i.e. 98.12%, was
achieved with 143 g/m3
EF (5%) applied
during 2 h. However, Table 1 shows no
significant difference between the 128.7
g/m3 and 143 g/m
3 concentrations
for 2 h
duration treatments. Nevertheless, the
highest mean was obtained using 143
g/m3 EF concentration. Hence, in order to
validate Vapormate® assays, 143 g/m3
EF
concentration was adopted.
Tunisian Journal of Plant Protection 55 Vol. 11, No. 1, 2016
Table 1. Effects of fumigant concentration and exposure duration on carob moth
mortality in date fruit
Fumigant Time
(h)
Concentration
(%)
Concentration
(g/m3) Mortality (%)
Ethyl
Formate
2 4 114.4 91.6 ± 1.3 a
2 4.5 128.7 95 ± 1.6 b
2 5 143 98.1 ± 2.3 bcd
3 4.5 128.7 95.5 ± 1 b
3 5 143 96.2 ± 2.5 c
Vapormate® 2 5 856 100 ± 0 d
Means within a column followed by the same letter are not significantly different
according to Tukey’s test at P ≤ 0.05. Values are means of four replications, and n =
50.
A satisfying mortality rate of
98.12% was obtained using 5% EF for 2 h
treatment. At this level, the increase of
the injected EF dose was not necessary
since the required efficiency of
fumigation (100% of carob moth
mortality) was almost reached. Therefore,
to perform these findings, another control
factor was introduced which is the time of
exposure. It was increased from 2 to 3 h
in order to perceive any possible
improvement in the disinfection
effectiveness. Statistical analyses (P >
0.05) revealed that the EF exposure time
did not significantly affect carob moth
mortality.
Effect of Vapormate® on carob moth
mortality.
Results from EF experiments were
reported to semi-industry trials with
Vapormate® in order to detect the
corresponding concentration of the
commercialized product, and to check the
possible improvement of fumigation
efficiency due to the potential effect of
CO2 incorporated in Vapormate®.
According to Table 1, the dose 856 g/m3
of Vapormate® had improved the
mortality rate which reached 100%,
consequently the synergetic effect of CO2
was demonstrated. However, statistically
there was no significant difference
between the fumigation efficiency using
EF or Vapormate®.
Effects of fumigation on date quality.
In order to evaluate the effect of
EF and Vapormate® fumigation on date
quality, fruits were treated with the
optimized conditions: 143 g/m3 EF (5%)
and 856 g/m3 Vapormate® during 2 h.
Results shown in Table 2 indicate that
there was no significant difference
between untreated, EF and Vapormate®
fumigated dates for water content, water
activity, and glucose content as well as
CIE Lab color parameters (P > 0.05).
Tunisian Journal of Plant Protection 56 Vol. 11, No. 1, 2016
Table 2. Effects of Ethyl Formate and Vapormate® on date quality parameters
Sample
Ethyl Formate
concentration
(g/m3)
Water
content
(g/ 100 g
DM)
Water
activity
(%)
Glucose
Content
(g / 100 g
dates)
Color
L* a* b*
Untreated
control 0 33.7 a 71.6 a 13.5 a 53.9 a 7.3 a 13.7 a
Ethyl Formate
Fumigation 143 33.1 a 70 a 13.6 a 51.3 a 7.7 a 13.7 a
Vapormate®
fumigation 856 33.2 a 71.4 a 14.7 a 52.6 a 7.5 a 14.5 a
a For each column, means followed by the same letter are not significantly different according to Tukey’s test at P ≤ 0.05. DM: Dry matter, n = 12.
Effect of EF and Vapormate® on
aroma volatiles of date fruit.
Forty-seven volatiles compounds
were detected, among which 9 alcohols, 7
esters, 10 aldehydes, 3 terpenoids, 7
ketones, 7 saturated hydrocarbons, and 5
unsaturated hydrocarbons (Table 3). The
identified compounds accounted for 92.4
to 95.5% of the total aromatic
compounds.
Table 3 shows that treating date
samples with the concentration of 143
g/m3 of EF and 856 g/m
3 of Vapormate®
for 2 h and after one week storage at 5°C
had no effect on aromatic compound
composition. Statistical analyses revealed
that there was no significant difference at
P > 0.05, for esters, terpenoids, saturated
hydrocarbons and unsaturated
hydrocarbons content between treated and
control date samples.
DISCUSSION Efficacy of EF and Vapormate®
on date quality and carob moth mortality
varied significantly among the tested
doses and duration times of treatment.
The EF effects on insect mortality are in
accordance with those of Griffin et al.
(16) indicating that four different
durations of exposure (1, 2, 3, and 4 h) to
EF did not improve the mortality of thrips
(Thrips tabaci and Frankliniella
occidentalis), obscure mealybugs
(Pseudococcus viburni), greedy scale
(Hemiberlesia rapax), and lightbrown
apple moth (Epiphyas postvittana).
Tunisian Journal of Plant Protection 57 Vol. 11, No. 1, 2016
Table 3. Composition of volatile compounds of date samples treated by 114.4 g/m3 of EF, 143 g/m3 of EF and 856 g/m3 of Vapormate® noted after one week of storage at 5°C
Compound l,r,ic. Controld 114.4 g/m3 Ethyl
Formate d
143 g/m3 Ethyl
Formate d
856 g/m3
Vapormated
Alcohols
2-propanol 516 8.6 b 20.6 a 15.6 ab 23.75 a
Isoamylalcohol 763 3.75 b 12.75 a 4.75 b 7.15 ab
1-hexanol 869 3.45 a 1.75 b 3.6 a 0.95 b
1-octen-3-ol 979 3.6 a 2.4 a 3.6 a 2.2 a
6-methyl-5-hepten-2-ol 993 - - 1.7a -
(E)-2-octen-1-ol 1065 0.95 a - - -
1-octanol 1070 3.15 a 2.0 a 2.25 a 1.05 a
phenylethylalcohol 1112 1.6 ab 2.15 a 1.8 a 0.65 b
1-nonanol 1171 1.25 a 0.85 a 0.95 a 0.35 b
% identified 26.35b 42.5a 34.25ab 36.1 ab
Esters
Ethylacetate 614 14.25 b 15.35 b 18.0 ab 21.2 a
Ethylhexanoate 998 0.4 a 0.65 a 0.95 a 0.5 a
Ethyloctanoate 1197 3.25 a 3.2 a 3.1 a 3.05 a
Ethyldecanoate 1395 1.45 a 2.2 a 1.35 a 1.25 a
Isobornylacetate 1287 0.4 a - - -
Ethylnonanoate 1297 - 0.65 a - -
Methyldecanoate 1328 0.45 a - - -
% identified 20.2 a 22.05 a 23,4 a 26.0 a
Aldehydes
Benzaldehyde 960 0.8 a 0.5 ab - -
Octanal 1002 1.45 a 0.6 a 1.35 a 0.4 a
(Z)-2-octenal 1052 9.9 a 6.15 b 10.8 a 2.95 b
(E)-2-octenal 1063 0.85 a 0.75 ab 0.5 ab -
Nonanal 1104 4.4 ab 3.65 ab 5.4 a 2.5 b
(E)-2-nonenal 1164 1.0 ab 1.0 ab 1.55 a 0.4 b
Decanal 1205 5.1 a 2.6 a 3.3 a 6.5 a
Tunisian Journal of Plant Protection 58 Vol. 11, No. 1, 2016
Undecanal 1305 - - - 0.6 a
(E,E)-2,4-decadienal 1316 0.55 a 0.8 a 0.45 a 1.0 a
% identified 24.05 a 16.1 a 23.35 b 14.35 a
Terpenoids
Linalool 1101 0.85 a 0.8 a - -
Camphor 1145 0.4 a 0.35 a 0.5 a 0.4 a
ß-cyclocitral 1222 - - 0.9 a -
% identified 1.25 a 1.15 a 1.4 a 0.4 a
Ketones
6-methyl-5-hepten-2-one 985 3.25 a 1.7 ab 1.8 ab 1.3 b
2-octanone 988 1.6 a - - -
2-nonanone 1092 0.85 a - - -
Carvone 1244 - 0.6 a 0.4 a -
2-undecanone 1294 0,9 b 0,75 b 0.95 b 2.7 a
(E)-geranylacetone 1455 5.2 a 2.05 a 1.9 a 2.0 a
(E)-ß-ionone 1486 0.4 a - - -
% identified 12.2 a 5.1 a 5.05 a 6.0 ab
Saturatedhydrocarbons
n-undecane 1100 - - 1.25 a -
n-tridecane 1300 0.3 a 0.6 a 0.45 a 2.45 a
n-tetradecane 1400 1.1 a 0.4 bc 0.85 ab -
n-pentadecane 1500 1.35 a -
-
% identified 2.75 a 1.0 a 2.55 a 2.45 a
Unsaturated hydrocarbons
1-dodecene 1192 - - - 1.6 a
1-tridecene 1292 - - - 1.4 a
(Z)-2-tridecene 1304 1.4 a 1.45 a 1.85 a 1.85 a
1-tetradecene 1392 - - - 2.25 a
Valencene 1493 0.5 b 2.25 a 2.05 a -
(E,E)-α-farnesene 1508 3.85 a 1.25 b 1.5 b -
Tunisian Journal of Plant Protection 59 Vol. 11, No. 1, 2016
% identified 5.75 a 4.95 a 5.4 a 7.1 a
Total identified (%) 92.55 92.85 95.4 92.4
a,b Means within the same column followed by the same letter are not significantly different according to Tukey test at P ≤ 0.05. c Linear retention indices (DB-5 column). d Average of percentages (2 replicates) obtained by FID area normalization (HP-5 column).
Indeed, De Lima and Manisfeld (12)
evaluated the mortality of four insect
pests: long-tailed mealybug, two-spotted
spider mite, Western flower thrips and
plague thrips using three different EF
concentrations and their corresponding
doses of Vapormate®. They have shown
that Vapormate® did not enhance the
efficiency of fumigation. Furthermore,
Simpson et al. (25) proved that the use of
EF combined with CO2 during one hour,
reduced mortality of Frankliniella
occidentalis, Pseudococcus maritimus
and Tetranychus pacificus attacking table
grapes, although other studies (7, 12)
revealed the synergetic effect of CO2 in
the improvement of the mortality rate.
Hence, according to statistical analyses,
fumigation with 5% EF for 2 h led to
optimum carob moth mortality and these
values were selected to be used for semi-
industry trials using Vapormate®.
Presently, literature reports that carbon
dioxide combined with other fumigants
may increase, decrease or has not affected
on the effectiveness of treatment (11, 26)
and it depends on the target pest and the
fumigated product. After reaching the
optimum treatment, EF effects on date
quality was tested for some
physicochemical parameters. Among
others, water content values showed that
the variety Deglet Nour was rich in water,
with an average of 33 g/100 g of dry
matter (DM). This analysis allows us to
detect some sensory properties of dates.
In fact, the decrease in water content may
result in a harder texture and pasty taste.
With other disinfestation alternatives,
such as the use of heat or microwaves,
loss of water is observed and estimated to
be 1.4 and 24%, respectively, which leads
to texture deterioration of the fruit (21).
Water activity remains unchanged in all
the samples, with an average value of
0.71. In one hand, it is favorable to mold
growth that may induce microbiological
damage lowering date quality (3, 11). On
the other hand, it accelerates Maillard
reaction that reaches its maximum for a
water activity between 0.5 and 0.7 (5).
Concerning reducing sugar content
(fructose, glucose), results revealed that
both EF and Vapormate®, unlike other
disinfestation techniques using heating or
freezing, did not affect the invertase
activity responsible for sucrose reduction.
Indeed, this enzyme leads to undesirable
changes of color and texture during
storage (31). In the literature, Jaddou et
al. (17), Reynes et al. (22), and Torres et
al. (28) have identified approximately 100
compounds for date palm fruit at stage
Tamar (mature stage) and confirmed that
the volatile composition changes
qualitatively and quantitatively. Statistical
analyses showed that there was no
significant difference between color
parameter values before and after
fumigation. These findings are in
agreement with those of Simpson et al.
(25) who assessed the EF effect on the
color of strawberries treated with 2.4%
EF for one hour. The effect of EF on
volatile date contents showed that 2-
propanol and isoamyl alcohol were the
Tunisian Journal of Plant Protection 60 Vol. 11, No. 1, 2016
major alcohols compounds, while among
aldehydes decanal, nonanal and (Z)-2-
octenal were the most represented ones.
These finding are in agreement with those
of El Arem et al. (14). Regarding esters,
ethyl acetate was the main volatile (14.25,
15, 35, 18.0, and 21.2% for control
sample, dates treated with respectively,
114.4 g/m3 and 143 g/m
3 EF and
commodity treated with 856 g/m3 of
Vapormate®). These results are in
agreement with those of Narain (19) for
maturity stage Tamar of Deglet Nour
variety. This ester has a similar flavor as
many berry-type fruits, banana, grape,
pineapple, peach, lemon, pear, and melon
(4). Generally, each volatile compound
refers by a characteristic smell. In fact,
Richard (23) has deduced that alcohols,
aldehydes, ketones and terpenoids are
responsible for the citrus floral and fruity
characteristics of date.
Our results demonstrated that the
main volatile compounds identified in
date palm fruit were Ethylacetate (Esters)
and 2-propanol (Alcohols). In addition,
the fumigation treatments using
Vapormate® showed no effect on
organoleptic quality of date fruits and
proved a high disinfestation potential. In
this context, further work will be focused
on the determination of the adequate
concentration of Vapormate® and its time
of exposure in the commercial scale.
ACKNOWLEDGMENTS
The authors would like to thank Linde Group for their support, supply of dates and assistance on the
process of dates’ fumigation. This project was
partially supported by the National Institute of Agronomy of Tunisia (INAT).
________________________________________________________________________
RESUME
Bessi H., Ferchichi C., Yousfi S., Guido F., Issaoui M., Bikoba V., Mitcham E.J., Grissa
K. et Bellagha S. 2016. Détermination de l'effet de l’Ethyl formate et du Vapormate®
sur l’efficacité de la désinfestation et la qualité organoleptique des dattes. Tunisian
Journal of Plant Protection 11: 51-62.
Parfaitement intégré dans l'économie tunisienne, le secteur des dattes connaît une grande expansion de
la production et des exportations. L’infestation est un problème majeur rencontré lors de la période de
post-récolte des dattes. Par conséquent, il est nécessaire de maintenir la qualité des fruits au cours de la
manutention, l'emballage et le stockage. Actuellement, après la restriction du bromure de méthyle,
l'industrie a besoin d'une solution alternative efficace et respectueuse de l'environnement contre les
insectes. Dans cette étude, le formate d'éthyle (EF) a été choisi pour la fumigation des dattes de la
variété Deglet Nour. Initialement, les essais ont été effectués à l'échelle du laboratoire en utilisant le
stade le plus résistant des larves de la pyrale du caroube (Ectomyelois ceratoniae). Le but de ce travail
est de déterminer l’effet de l’EF et du Vapormate® sur l'efficacité de la désinfestation et la qualité des
dattes. A cet effet, trois concentrations EF (114,4, 127,8 et 143 g/m3) et deux durées d'exposition (2 et 3
h) ont été testées. Les résultats ont révélé que la combinaison la plus efficace était de 143 g/m3 de EF
pendant 2 h qui a provoqué 98.12% de mortalité. Ensuite, des expériences ont été réalisées à l'échelle
semi-industrielle avec Vapormate® qui est la version commerciale d’EF contenant une combinaison
d'EF et de CO2. Le taux de mortalité a été encore amélioré, atteignant 100%. Cependant, l'effet
synergique de CO2 n'a pas été démontré. En outre, les effets de l'EF et du Vapormate® sur la qualité
des fruits fumigés ont été étudiés à travers leur couleur, leur teneur en sucres et leur composition
aromatique. Aucune modification de la qualité après la fumigation n’a été observée.
Mots clés: Formate d'éthyle, fumigation, pyrale du caroube, qualité des dattes, taux de mortalité,
Vapormate®
________________________________________________________________________
ملخص
Tunisian Journal of Plant Protection 61 Vol. 11, No. 1, 2016
اليزابيث ميتشام وفيرونيك بيكوبا ومنال عيساوي و فالميني غيدووسندس يوسفي وسيرين فرشيشي و هيثم الباسي،
والجودة الحسية تطهيرنجاعة العلى ® وفاپورمات ثيلاإل تحديد تأثير فورمات 2016.. وسهام بالغة كوثر ڨريصةو
Tunisian Journal of Plant Protection :11 51-.62 . فاكهة التمرل
اإلصابة وتعتبر نتاج والتصدير. في اإل اكبير اارتفاعتماما في االقتصاد التونسي، عرف قطاع التمور في تونس مندمجا
على جودة ةفظاحمالتمور. بالتالي، من الضروري الجني هي المشكلة الرئيسية التي يواجهها هذا القطاع خالل فترة ما بعد
لمكافحة لحل بديل الصناعة تحتاج الثمار أثناء المناولة والتعبئة والتخزين. حاليا، بعد منع التبخير ببروميد الميثيل،
دقلة صنف ( لتبخير التمور من EF) اإليثيل فورمات حافظ على البيئة. في هذه الدراسة، تم اختيارموناجع الحشرات،
الخروب يرقات عثة دى األكثر مقاومة ل الطورنور. في البداية، أجريت االختبارات في نطاق المخبر باستخدام
Ectomyelois ceratoniae. تحديد تأثير إلى هدف هذه الدراسة وتEF و ®Vapormate تطهير وجودة نجاعة العلى
غ/م143 و 127.8 و 114.4)التمور. لهذا الغرض، تم اختبار ثالثة تركيزات 3
ساعات(. كشفت 3و 2( ومدتا تعرض )
غ/م 143 ياألكثر فعالية هالمعاملة النتائج أن 3
ن الوفيات. بعد ذلك، م %98.12لمدة ساعتين وهو ما سبب EFمن
تحتوي على مزيج من التي EFوهو النسخة التجارية من Vapormate®أجريت التجارب على نطاق شبه صناعي مع
EF من ثاني أوكسيد ي، لم يثبت تأثير تآزرلكنو ،%100تحسن معدل الوفيات ليبلغ حيث ،وثاني أوكسيد الكربون
من خالل اللون، ومحتوى السكر Vapormate®و EFـ دراسة جودة الثمار المدخنة ب تالكربون. باإلضافة إلى ذلك، تم
التبخير.هذا والتكوين العطري. لم يالحظ أي تغيير في الجودة بعد
Vapormate® ، معدل الوفيات،عثة الخروب فورمات اإليثيل، التمور، جودة تبخير،: مفتاحيةكلمات
__________________________________________________________________________
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