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: sondes.yousfi@outlook.fr, 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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