MB Alternatives in dried fig sector1 DO VACUUM CHAMBERS HAVE A FUTURE AFTER THE LOSS OF METHYL BROMIDE? Patrick DUCOM National Stored Products Laboratory.
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MB Alternatives in dried fig sector 1
DO VACUUM CHAMBERS HAVE A FUTURE AFTER THE LOSS OF METHYL
BROMIDE?”
Patrick DUCOM
National Stored Products Laboratory
France
MB Alternatives in dried fig sector 2
VACUUM CHAMBERS IN TURKEY AND ELSEWHERE
There are at least two vacuum chambers for figs, surely more, in turkey.
E.U., mainly France and Italy (dried fruits, seeds, rice), Algeria Tunisia for soft-fresh datesCalifornia (bactericide for walnut meat)
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They are used with MeBr which allows a very quick disinfestation, all stages, at any temperature. 2 to 3 runs a day are possible.
It is a part of an industrial process with no storage and no re-infestation.
That allows a quick logistic in a continuous process.
Without MeBr, what to do?
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Companies are still using processing with vacuum and are not aware of MeBr ban in Dec.
One case of CU was given for “vacuum” reasons: legume seeds processing
All others are hoping in a new fumigant for January!!!!
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SHORT HISTORY
Vacuum chambers
have been using long
ago, mainly for non penetrating fumigants like HCN, EtOx, EtOx+ CO2, CS2,…
In 1934, LEPIGRE was already improving what he called this « old » technique….
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Gas penetration was the target and the practice used three ways
Sustained-vacuum fumigation
Vacuum fumigation with simultaneous admission of air and fumigant
Vacuum fumigation with atmospheric pressure restored after a period
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Research in the 40’s - 50’s was focused on factors improving penetration to find the best one.
The diffusion law says gas diffuses better under vacuum and studies with CTP measurements show the sustained vacuum is the best way. But sorption is greater in this circumstances…..
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Finally, practice showed that time could be greatly reduced:
Typic : 80g/m3 – 4h.
Since these years, vacuum fumigation is running with MeBr, with success, mainly for products like compressed dried fruits, tobacco leafs or for quarantine.
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One question was never really answered: What is the intrinsic action of vacuum on the toxicity for insects?
It was studied case by case, for instance , for diapausing larvae of Codling moth, vacuum is two times more effective in terms of CTP than with NAP.
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WHAT TO DO WITH THE VACUUM CHAMBERS WHEN MEBR WILL
DISAPPEAR ?
To destroy them and work at NAP with toxic gas
To use for anoxia or insect emigration
To keep for new gases
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Conditions for a Fumigant Candidate for vacuum
1 - To be a fumigant, i.e. a toxic gas
2 - to more effective under vacuum than at NAP, allowing a quick logistic
3 - Registration is somewhere already obtained
4 - MRL’s are pending under codex alimentarius process and will be soon accepted in all the buyer countries
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fumigants for vacuum
Few candidates, but promising in the next 10 years:
Few private companies are interested, governmental bodies take patents.
Sulfuryl fluoride : SO2F2
Propylen oxide : PPO
Carbonyl sulfide : COS
Methyl iodide : CH3I
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To keep for new gases
In the short term, only one fumigant could replace MeBr: Sulfuryl fluoride, SO2F2
Reasons: There is a pesticide company who supports it (DowAgroscience)
Resarch and regulation are on the way
Problem: to convince Dow to sell SO2F2
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SO2F2 properties
Molecular weight: 102.07
Boiling point: - 55.2°C
Gas Caracteristics: colourless, Odourless.
Specific weight: 4.2 g/l
Relative density (air=1): 3.5[1]
Diffusion (perméation): very good
Non flammable
Water solubility 0.75g/l at 25°C
Non corrosive for metals
Xn
[1].
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EFFICAY AT NAP
Very effective on active insects life stages even pupae.
The corresponding CTP’s are of the same order than those necessary for MeBr : 200- 300 at 15 - 20° C
Typical: 15 g/m3 – 24h at 15-20°C.
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EFFICAY UNDER VACUUM
Some studies have been carried out: Zettler and Leesch,
As with MeBr, a factor 2 exists on all stages except eggs
There are differences between species
Süss in Italie began commercial test under vacuum for dried fruits.
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EFFICAY UNDER VACUUM
In France , we have been working for 4 years.
Results are promising, even for difficult situation.
We confirm that CTP is divided by half.
The problem seems coming from Carpophilus spp which are more tolerant than Plodia.
Experiments are running at 15, 20 and 25°C with eggs
Of 1, 2 , 3 and 4 day old (depends temperature), exposure time 4h.
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EFFICAY UNDER VACUUM
Carpophilus eggs
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EFFICAY UNDER VACUUM
SO2F2 works better with CO2
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Highest tried CTP
% Mortality
SO2F2, NAP 212 52
SO2F2, NAP + CO2 20%
220 63
SO2F2, VAC 280 97
SO2F2 VAC + CO2 20%
235 98
SO2F2 works better with CO2 :Efficacy on
diapausing pupae of Leucoptera scitella Z (leaf miner)
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SO2F2 RESIDUES
Dow Agrosciences is in the process to have residues values in USA and are beginning to apply for Codex
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In or On Raw Commodity:
In or On Raw Commodity: F-
(USA)
In or On Raw Commodity:
SO2 F2 (USA)
Figs 5 0.05
Raisins 30 0.004
wallnuts 12 2
RESIDUES :Dow is in the process to have residues values in USA (table) and are beginning to apply for Codex Proposed (USA)
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FOR A FUTURE
For those who have vacuum chambers and the corresponding logistic, the economical risk is too high
to change all the system now.There are hopes to have alternatives adapted to these chambers, BUT, resarch is needed to accelerate the
implementation of the new gases: Research on efficacy
, Setting up international (residues) and national (registration) regulations.
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Studies to be carried outEfficacyRelationship between Species – stages - Dose - time – temperatureThe stages to be study: eggs.ResiduesDow is in the process to present it’s data to the codexPractical residues in the future turkish processRegistration in the country
Practical conditions for implementation in dried fruit industry
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Methyl iodide : CH3I (MeI)
The fumigant the closest of MeBr.First trials under vacuum are promising.
Toxicological data to be provided present a very big investment.
Long way!!!!!!!!
MB Alternatives in dried fig sector 26
PROPYLEN OXIDE (PPO)
Only registered in US for sterilization of packaged foods of Beverages, herbs and spices.Izikberand al, Zettler and al.found that PPO was insecticide but at high dosage and long exposure time if Temperature is below 30°C
?????
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CARBONYL SULFIDE (COS)
In the light of some preliminary tests, No promising under vacuum
(less effective, gives sulphur odour)
?????
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Destroy and work at Normal Atmospheric Pressure
Phosphine
To make the same job than with MeBr under VAC at 20°C, time is 5 days, the volume (V) of the new chamber must :
V = Vvac x MeBr runs per day x 5 days (duration)
Example, 2 runs, Vvac= 60 m3 V= 600 m3
Duration= 5 days + 1day handling (load/unload)
Two chambers are necessary to have figs every day.
If temperature is 15°C, 7 days V= 840 m3
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Destroy and work at Normal Atmospheric Pressure
SO2F2
To make the same job than with MeBr under VAC at 20°C, time is 1 days, the volume (V) of the new chamber must :
V = Vvac x MeBr runs per day x 1 days (duration)
Example, 2 runs, Vvac= 60 m3 V= 120 m3
Duration= 1 days + 1day handling (load/unload)
Two chambers are necessary to have figs every day.
If temperature is 15°C, 2 days V= 240 m3
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