Initiative for Future Agriculture and Food Systems (IFAFS) Meeting
and Radio Frequency Workshop
University of California, Davis
October 24-26, 2001
Attendees;
UC Davis
Beth Mitcham, Xuqiao Feng, Jenny Bower, Bill Biasi, Tiffanie Simpson
USDA Wapato, Washington
Jim Hansen, Millie Heidt
Washington State University
Juming Tang, Shaojin Wang
USDA Weslaco, Texas
Guy Hallman, Carlos
USDA Parlier, California
Judy Johnson
Strayfield, UK
Tony Koral
Minutes from Thursday, October 25, 2001
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We started the day with Jim Hansens first powerpoint presentation – ever! Jims
project was on the use of RF treatment to disinfest cherries of codling moth, hot
water being substituted for RF treatment.
Washington fruit were infested, held at room temp overnight then treated at the time,
temperature combination required before hydrocooling to 4oC. All of these
treatments were done using the bath system.
California fruit were infested, cooled, and then subjected to a prebath at 40oC before
they were treated in either the shower or the bath system, then hydrocooled.
The temperature of the Washington water heating system is controlled at the outlet of
water heater. The water heater circulates the water constantly, and is set at about 12oC higher than the required bath temperature.
Fruit was placed into a fine mesh bag for treatment. One fruit had a temperature
probe inserted and sealed into the fruit with silicone stopcock grease. Probes were
used which had the sensor only at the tip).
Comparison of the heating curves shows that the bath and shower heated at the same
rate. However, temperature varied more in the shower.
Steve Drake checked quality of the treated cherries. He found that the fruit were very
tolerant of the treatments, eg 50oC + 15 mins ok.
Regarding the mortality of codling moth larvae, the shower appeared to be more
efficacious than the bath even though the heating rates were the same. Also,
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California fruit were different to Washington fruit, possibly due to the size
difference.
Hydrocooling reduced the efficacy of the treatments. This is presumably because
uncooled fruit had a greater heat load, increasing insect mortality.
Jim feels that it would be better to concentrate on treatments for cherry fruit fly than
codling moth. Apart from being easier to kill, this insect can be a major problem for
producers sending fruit interstate; whole plants may be shut down if flies are found.
Conversely, codling moth is not a real pest of cherries. Cherries are not a preferred
host and the larvae do not do well in the fruit, so are unlikely to reach maturity.
Although treatment for codling moth is required, it is unlikely to be scientifically
justified.
Jenny then talked about the work Beth’s group has done on heat treatments of
cherries.
Preliminary work indicated that the shower was slightly less damaging to the fruit
than was immersion in a hot water bath. We also found that adding CaCl2 to the
treatment water reduced damage. Treatments therefore used the shower, with or
without CaCl2.
Bing cherries were used from 3 different harvests. On the first 2 harvests the fruit
were warmed to room temperature in water, on the 3rd occasion they were preheated
to 40oC in a water bath. They were treated under the hot water shower for various
time and temperature combinations based on the moth mortality information
provided by Jim. They were finally hydrocooled under a second shower, and stored
under conditions that simulated either air (2 days) or sea shipment (14 days).
Following storage and 14 hours at 20oC, firmness and color were measured, and skin
and stem browning, pitting, splits, cracking and overall acceptability were recorded.
The effect of treatment time on damage was modeled for each of the measured
quality attributes. Storage life was considered over when any one of these attributes
exceeded allowable limits, as predicted by the model. Limits were set at double the
control values for most attributes, and at what seemed like reasonable limits when
the control showed little or no damage.
Comparison of the thermal tolerance curve for cherry fruit with the insect mortality
curves from Jims data suggests that there are very limited time/temperature
combinations which result in 100% mortality but do not excessively damage the
fruit.
There was then a discussion of the different methods used to develop both the insect
mortality curves and the thermal tolerance of the fruit curves. Some of the variation
in the results may be due to differences between the whether the fruit or the water
temperature was used in calculations, as well as differences between Washington and
Californian fruit.
Juming then talked about their work on thermal death kinetics in walnuts heated with
RF.
At WSU they have developed a computer-controlled thermal heating block. This
consists of aluminum pads inside an insulation box. Each compartment can be heated
at a similar rate to that experienced during RF heating. Insects are sandwiched
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between the heating blocks, and can be treated 200 at a time. Temperature sensors
are located in the air and bottom plate. Heat treatments can be combined with
controlled atmospheres or special gases. The device can test a wide range of time /
temperature combinations, and is used to develop a mortality curve.
WSU has developed a model for estimating Probit 9 mortality – this is not possible
to actually test. If 600 insects are all killed by a temp time combination, then the
model predicts that adding 20% more time will give Probit 9 mortality. This is being
published soon in Journal of Stored Product Research
Data on different time / temp combinations that result in 100% mortality were
plotted for Indian meal moth, codling moth, navel orangeworm. This was shown to
be a Log relationship. Also, the lines are parallel for all 3 species, indicating that a
similar reaction is occurring in each case, such as denaturation of a protein. Navel
orangeworms were toughest species to kill. Also, diapausing insects were harder to
kill than non-diapausing insects. However, this is true only up until a certain
temperature, as the diapausing insects will die quite suddenly once a particular limit
is reached – they effectively “fall off the cliff”.
Of the different life stages tested, fifth instar navel orangeworm was the hardest to
kill. It was this stage that was used to infest walnuts
The dielectric properties of insects were also measured. This was done using an
impedance analyzer and a container of mushed up insects, a water bath jacket was
used to control temperature. A range of temperatures was used with different
combinations of frequencies + energy. This showed that increasing the insects
temperature increases their dielectric loss factor – ie, the insects absorb more energy
as they heat.
Heating does not change the dielectric constant of walnuts by nearly the same factor.
Furthermore, there is a thousand-fold difference in the dielectric loss factors of the
walnuts and insects. May be due to characteristics of insects in electric field, and is
not fully explained by moisture content.
Juming has measured the temperatures of “insects” and walnut kernels during
heating (insects were mashed up inside a pouch with a temperature sensor, later
replicated using salt solution and gel). Walnuts heated more slowly than the insects.
An initial study with limited numbers found 100% kill of navel orangeworms after 3
minutes at 53oC. Five minutes exposure to RF killed 100% of larvae in walnuts.
Studies of PV and fatty acid values have suggested that it may be possible that RF
heat treatment inactivates some enzymes associated with rancidity.
Beth – our quality evaluation showed that RF heating dried the kernels. It also
appeared to make them harder / more brittle.
Juming – we need to do a shelf life study, look at how quality changes over time. It
could be possible to use shorter treatment times or lower temperatures than we have
tried so far, as there appears to be a large difference between the mortality curve and
the product tolerance.
Juming – we haven’t got any data to show about almonds yet, but they should be
much easier than walnuts because they are not as inclined to rancidity. Although they
are a more regular shape, orientation during treatment is important so we need to
work on standardizing that.
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Juming – we have set up a new website, describing our projects and published
papers. This is currently a preliminary version, and there are lots of gaps needing
information. Keywords that will find it include IFAFS Project, USDA, codling moth
and quarantine treatment. Lists primary investigators, links to their website, also
links to USDA, WSU etc. There are also links to relevant journals, organizations
(industry and research). Pictures are on there of the people involved, schedules for
meetings, minutes of meetings, and a map of the US showing lab locations. A time
plan showing projects and objectives, published articles, media reports, presentations
etc
Beth – maybe the front page should have pictures of RF equipment, descriptions,
crops, insects, as well as a map of site…There was some discussion about how the
information should be organized, where media reports should go relative to
publications etc
Juming – we are putting our publications on the site. Beth – mightn’t that breach
copyright of the journals? Some discussion about this issue, as well as whether
reports to industry should be put up there, given that they might not always be
positive – need for discussion with industry on this point.
Juming – the map showing locations could include images and a list of facilities at
each, this could be useful information for industry.
Shaojing – I have been putting on pictures of fruit with insects and insects at
different larval stages. These pictures are from other web sites.
Beth – each person needs to go through the web site, find places to put their
information, Guy - yes we are doing that, I will send some pictures of insects.
LUNCH
After lunch we looked at where we could drill a hole in the machine so as to divert
the hot air from the oscillator cooling fan away from the treatment chamber. Tony
showed us how we could change the piping so as to exhaust through the machine
side.
We then heated some walnuts. The walnuts were placed in large tub. To increase the
power the trombone fixtures were lengthened by moving one bridge connector 4
holes to the right and the top plate was moved down. This increased the power to
0.8A. The power increased as the nuts heated.
We then moved upstairs to the meeting room again
Juming went over the objectives of the IFAFS. This was sent as handout to everyone
via email. The new version is attached at the end of these minutes.
Juming – The insects we listed to examine mortality of in life stages are set out there,
Judy is that right? Judy – We’ve done a quick and dirty examination of navel
orangeworm stages, but still have to do Indian meal moth eggs. Juming - Codling
moths are pretty well finished? Jim – yes, codling moth are pretty well done,
although we still need to redo some of our tests using field materials.
Juming – We still need to finalize the dielectric properties of commodities. Shaojin –
however, a lot are already completed ie cherries, apples, grapefruit, almonds, most of
the insects. We still need to do citrus. Judy – I think we need to redo these tests using
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different life stages, especially pupae, as they differ considerably in fat content and
so their dielectric properties may also vary.
Juming – The next step could be to look at thermal responses of commodities. We
have already started analyzing cherries using a hot water bath or shower, apples we
are starting this year, almonds are done, pears we still need to do as well as citrus.
Guy – We are doing citrus, but why the water bath rather than RF? Juming – Well, if
products won’t take the heat at the surface, there’s no point going further. Guy – why
not try the RF now that we have the machines? Juming – we need to be consistent
with what we’ve done before. Beth – Jim, which pears are you going to do? Anjous?
Jim – well, we need advice on that. Beth - Maybe we should do Bartlett, you could
do Anjou and Comice.
Juming – We have a problem with uniformity as we are so far from the source of
fruit… Judy – and the source of insects too. Juming – so maybe Beth can do more
work with fruit quality next year
Juming - So the stages are; insect mortality, then the fruit tolerance, then develop a
protocol
Juming - Another problem is that large fruit might not heat uniformly, unlike small,
tightly packed walnuts. Tony – so long as the fruit are packed uniformly into a bed it
should be ok, you can decide later if you need to use water. Beth – so maybe we
should try air first, see how we go Tony – yes, if you were to use a deep bed, that
might improve uniformity
Tony – While we are talking about machines, there is an RF unit that will take bales
of straw going for basically however much you might want to pay. The customer is
in Norway and has changed business so doesn’t need the machine. It is ideal for
treating bales, but it is a big machine with a continuous feed. Customer just wants rid
of it. The thing is worth $300,000, and been used for literally about 20 hours.
There was a discussion of other objectives – include creating website (done),
education, media etc
Juming – So, I think we are right on track. We are now getting RF installed, next
year we can really start using it. Protocol for walnuts is getting ready. Judy – we
don’t know that we can’t go less than 5 minutes, 4 might be ok. There was then a
discussion of possible times that might be effective, what might be the highest
temperature with survivors. Judy has never seen survivors with RF. Beth – well, if
the insects are heating to 70oC that’s not surprising. But I think we need to get some
treatments where they survive, find out the lower limit. Judy Yes. The temperatures
we are talking about are the walnut temperature, not the bug temp. We need to know
not just that we are at 100%, but how far above 100% we are. Also, when we scale
this up we need to know the bottom line. Navel orangeworm is not currently a
quarantine pest, and so developing a Probit 9 curve isn’t necessary (yet), but for
codling moth it is.
Beth - well the bottom line is the insect temp we have already developed, maybe we
could just go with using the gel rather than infested walnuts. Juming – although the
insects heat faster than the walnuts, other products will be different. We want to
make the whole process as fast as possible.
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Tony - but the same thing can be achieved by making a longer tunnel, joining a
couple of machines together. Admittedly that is more expensive, in general the
bigger the machine the more cost effective it is.
There was a discussion on how many walnuts would need to be processed / hour.
Mariani process 300 bins/day, each bin has 1100 pounds. Diamond Walnut is about 3
times that size. That makes 18,000 kg/h Tony – calculation for 30oC change in temp
comes out at about 261 kW, that’s not too big, we could do that using several 85 kW
units. The cost depends on what they need, how simple or sophisticated it is, but it
would probably work out at something like a million dollars. Working life of the unit
would be about 10 years at least. It would require something like 500 kW power/h –
whatever the cost of electricity would be. Beth - at 5c kW, would run to about $600
day for electricity. Juming – sounds like it could be quite economic. Tony – yes,
$1million on a plant isn’t that huge really, would have to pay off within about 3
years but could be possible.
Tony – The bins that you have downstairs are ideal for treating products in. Two of
those bins side by side approximate the width of regular commercial machine,
although they would of course be only about 1/7th length. That is a disadvantage with
your system, but is static rather than continuous, a continuous system would improve
uniformity. Uniformity of heating should be checked both within the machine and
within the product. Also, how much tolerance of non-uniformity can you accept? If
the heating criteria can be met with your unit, than it should be possible to make it
work in industry.
Juming – we need to check on type of walnuts, variety can change uniformity of
response. Beth – Hartley is the main variety of interest Bill – why is there so much
variability? Tony – they shouldn’t vary that much Juming – differences are due to
the kernel filling more or less of the inside of the shell in other varieties, Hartley is a
good variety for inshell use because it is fairly loose within shell. Tony – well, now
you can use a deeper bed, that should improve uniformity. I don’t think that
thatshould be a big issue, just change a few settings on the machine should be
enough to overcome such variability.
Jim – is there any way we could trial this process on a continuous machine? Tony –
Yes, there is a full scale machine down the coast from here. It does textile drying,
you could probably run that slowly and it would work ok. You would probably go
down there with some containers of walnuts, you could do a very accurate simulation
so long as customer is agreeable.
Beth – Juming, do you want to run through what people are going to be doing more
specifically? Just to make it clear….
Juming – ok, we’ll go through it.
Objective 1.
This objective relates to developing a model of insect mortality.
Guy – we have applied for permission to send apple maggots to Washington State so
that Jim can work on them, I don’t think they’ll let us do that but we are at least
going through the motions.
Judy – We’re not doing diapausing navel orangeworms. They are not found in stored
walnuts due to the timing of harvest etc. However, we are working on other stages as
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well as different stages of Indian meal moth + comparing cultivated and field
collected insects.
Jim – we are about to start working on diapausing mites and planning to work on
scale insects and mealy bugs
Juming – What about fruit fly? ‘
Gus – we are working on Mexican fruit fly, but not until 2002
Jim – we want to work on cherry fruit fly, but that is dependant on getting additional
funding.
Objective 2
This section relates to fruit heating, in particular issues such as testing uniformity
and trying different approaches. These might include saline solutions, treating fruit
while it is moving etc.
Tony – in order to move fruit around in your system during heating you would have
to construct a shaker or roller of polypropylene. That is quite possible, but the motor
would have to be either outside the machine or inside in a corner with a protective
box around it. You could use a vibration system, anything that moves the product
could be useful. Increasing the amount of product will also increase uniformity, as
will placing the product in a solution which has the same density as the product. I
don’t think just coating the product with water will help.
Juming – we have tested uniformity in our machine using a set of 10cm high PVC
tubes filled with water or solution. After we heat it, we take it out and put on a lid
with 30 thermocouples. The readings from these show whether the water has been
uniformly heated. Tony – You could construct such a thing out of Lexcen or
polypropylene, Plexiglass (Perspex) will heat.
There was a discussion of whether almonds would be easy or difficult, and whether
pistachios would be easier, and what insects are pests of pistachios and almonds.
Judy – could we use bags to put the insects in and restrict their movement Tony –
you could use polyester bags, those are inert and will do nothing in RF. Judy – but
the navel orangeworms will chew straight through those, they will chew through
most plastics.
Objective 3
Commodity responses
Jim – I think we need to do more on cherries to define the effect of harvest and size.
Apples also, although not pears this year. We will do two cultivars of apples – Fuji
and Red Delicious; maybe screen some others if possible.
Beth - we are also working on cherries, just Bings. Jim – We will probably work on
at least 2 varieties of cherries, possibly 3.
Beth – you think almonds are done? Juming - yes Beth – but we’ve never looked at
quality attributes as we have with walnuts Juming – such as determining moisture
content etc.? That should be done once we are confident that we are heating
uniformly.
Beth – we might also do Bartlett pears next season.
Guy – We are going to do some on citrus in 2002
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Objective 4
Juming – this is where we move to RF rather than hot water, develop protocols
Beth - we will do sensory attributes of almonds and pistachios – color, moisture,
taste, hardness. Also cherries. Pears with rf will be the following year.
Jim – we are working on these same attributes as Beth was talking about but for
apples and cherries, treated with rf.
Beth – how about we leave it there for tonight, everyone’s getting tired and we’re
ahead of schedule anyway.
Judy – well I won’t be here tomorrow, so we need to discuss whether the meeting
next year will be at Fresno or not, and when it should be.
Juming – Is October a good time, or would June be better? October is good for me.
How well will Fresno be set up by next year? Judy – well we have a conference
room, and motels nearby.
It was then agreed that next years meeting will be in Fresno, and the following year
(2003) will be in Wapato.
There was a discussion about whether Jumings small, trial RF unit would be useful
to Judy, who could use it down at Fresno. Or whether someone else could use it.
Tony – that would be fine, we might need to occasionally borrow it for some special
purpose, but that would be uncommon. Better that someone is using it.
Minutes from Friday, October 26, 2001
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We started day in the lab, and tried heating apples in bins. The apples were severely
burned at all contact points due to focusing of the RF energy through those areas. We
then tried placing the apples in fibreboard trays which were sufficiently widely
spaced that the apples were kept apart. Three trays were stacked on top of each other
so that the fruit interlocked. The power was reduced to 0.5A and the treatment
conducted for 3 minutes. Heating was much more even, as measured with probes
inside apples at various points in the stack. However, the apples still showed singe
marks where they had contacted the fibreboard, even though these areas were not
quite as distinct as those where apple-to-apple contact had occurred.
When we returned upstairs there was a discussion about how the apples could be
singulated for treatment by being held in rings or cups of nonconducting material, or
alternatively placed in water.
Juming – So we need to work on developing protocols, try different things, and
importantly need to communicate what each person is doing
Gus – The best way is probably by email, simply set up an email list and reply to all
on each communication
There was a discussion of different things that could be tried, such as rolling the
fruit, saline solutions etc
Juming – even if we solve the contact area problem, could get another problem with
the core being cooked. Probably you (Beth) need to focus on quality issues, our
group to focus on engineering type problems and computer simulation, Jim can focus
on insect mortality kinetics. In other words, we need to use the strengths of each lab.
Jim – I like the idea of treating the fruit in a water bath, however, the problem seems
to be the recycling
Juming – but maybe the water could be used to preheat the apples to 40oC, that
would help the treatment as a whole as the cores heat faster than the skin anyway
Jim – it would be interesting to see the effect of that treatment on mortality of
surface pests
Guy – When we have a question or idea or find something out maybe we should
communicate that to the group
Jim – During our cherry experiments I sent data to UCD via email and Jenny
analysed it, which seemed to work out quite well. However, the powerpoint files
may have been a problem because they are very big
Jenny – it is generally better to send data rather than a graph anyway
Xiuqao – wouldn’t it be beneficial to heat the fruit surface preferentially if that is
where the pests are?
Juming – yes but we don’t want to waste energy heating water. However, if the water
is recycled then we don’t waste either energy or water. We just have to cool the
water slightly between treatments, that way it can be a continuous flow
Guy – we need to use chlorine in the water as well, and see how levels of that are
affected
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There was a discussion of some of the engineering problems involved in recirculating hot water and controlling temperature.
Beth – so then if we are not to focus on this engineering problem, what should we be
doing?
Juming – focus on Objective 3, work on Objective 2 as well, but mainly look at
quality issues. In particular, we need to make sure treatments are uniform in order to
make the results useful to industry. I don’t want to discourage people from doing
things, the main thing is to make sure we communicate well and avoid doubling up.
Beth – well, we might do some tests on pears out of storage, but then there are the
almonds to do too.
Jim – we can work together on cherries. Do you think that the stems will affect the
way that the cherries heat?
Juming – we need to match the dielectric constant of the water to that in the fruit,
that way the wave will not bend, and the energy will pass through as though the fruit
+ liquid are a uniform object.
Jim – how efficient is RF heating? I’m thinking that if some fruit only need to be
treated on the surface, then RF could prove to be a more expensive way of heating
water than propane….
Guy –yes, RF might not be the way to go if we only need surface disinfestation.
Other methods of heating fruit might be better. For example, we have done some
work using Omec heating. This involves putting metal plate electrodes in a tank, and
then passing a current through the water to heat it. Our problem was that we didn’t
have any way of accurately measuring temperature as the electric field interferes
with output from thermocouples, but now with the fiber optic sensors that should be
less of a problem.
Jim – we actually started doing that too, trying to pass electricity through insects in
solution.
Guy – it’s the same thing, and you can change whether the core or surface heats
faster by changing the saline content of the solution
Juming –if the fruit has a waxy surface does that restrict the heat from passing
through?
Guy – well it has worked with kumquats, they are pretty waxy. Now we need to try
the process with larger fruit. No one makes these machines at the moment, although
there are ones being developed for heating stew inside tubes. Similar systems are
used on a small scale for rapid water heating (Zippy heaters), however, larger scale
equipment has not been available.
Juming – now we need to talk about field tests
Beth – well how about we start with walnuts
Juming – maybe next year we could get Tony back to help us develop a protocol for
almonds, then we could do some demonstrations for growers. Judy made a good
point in that we need to find the bottom line, by next year we should have that
information and will be in a better position to recommend a whole process
Beth – also, what about long-term storage tests. Should we wait until we sort out
which are the optimal treatments…
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Juming – well, I feel that we need to move ahead and get on with that part. We
should avoid repeating previous work
Juming – so when we get the basis of these RF treatments sorted out, maybe we
could organize a symposium, invite people from Israel etc, put the proceedings
together as a chapter for publication
Beth – when?
Juming – maybe in 4 years time. If we start organizing it in the 3rd year of our
project, I think people should be excited and interested in it by then. We could use
money from BARD and such. So that would mean a 2003 start
Beth – periodically there are grants you can apply for which cover special projects
like this, as in organizing symposiums.
Beth – We need to talk more about grants. Those who are working on the nuts, the
call has come up for extra industry grants, extra money would be useful and also gets
us out in front of industry
Jim – we have a new permanent person who will be starting to work on fruit fly and
apple maggot also. His name is Wei Ee, and he will be using the heating block
system. He will have to go to those parts of WA where apple maggot is found. At the
moment he is doing a study evaluating different survey techniques for fruit fly
Jim – I also have project looking at RF effects on spider mites, eggs, other surface
pests, and have a proposal in to examine the effects of RF on different cherry
varieties
Beth – we will also be submitting a proposal to our cherry advisory board asking for
extra funding. We are not asking the pear people for any money at this time, they are
not that interested in export and I feel we should wait until we get some good data to
show them anyway
Jim – Lisa and I have a grant from APHIS looking at surfactant dips and hot water
sprays on pear pests
Beth – we have also been looking at Silwet. The problem we found was that it reacts
with the fruit lenticels
Jim – on some products that may not be a problem though. We are interested in its
effects on diapausing spider mites. We are working on building up colony of grape
mealy bugs, maybe san jose scale too, so that we can start working with those pests
also
Beth – the BARD deadline has passed for this year, we probably need to work on
these projects for next year. Any other grant opportunities??
Juming – there’s the NRI grant, they were very interested in our proposal last year
but there was too much overlap with another project. They also felt we had already
gotten too much money and needed a different angle. This happened because the
grant was money for basic research; they had already given us money for applied
research. So Jan 15 is deadline for that one, need to repackage our proposal, add new
partners etc. I am thinking that we can look into heat shock proteins, examine
preconditioning effects on insect tolerance, look at thresholds Another issue is
whether I declare the money that is coming to me or the total money that goes to all
the people involved.
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Guy – you need to note on the grant that you are not getting all this money, that it is
split between the collaborators
Jim – occasionally APHIS will provide funding, we had one last year
Guy – I got about $30,000 to look at effect of irradiation on some pests
Beth – apparently APHIS has had extra money this year. However there might not be
so much next time round
Guy – I think there is a need for research for the east coast. At the moment they are
totally reliant on methyl bromide. John Wise at Michigan State is looking at cold
treatment of apples for apple maggot. In Texas we are considered infested so we can
work on all insects including apple pests from other areas. This might be worth
exploring once we can convince the people on the east coast that methyl bromide is
not the way. Also blueberries, they are fumigated now, and although some people
have looked at irradiation it is an expensive option. They are not interested now
because they don’t feel under pressure to phase out methyl bromide, but maybe we
should at least make contact. It would be good to get someone from east coast
involved in our work
Juming – what about the Dept of Energy? They have lots of money…
Beth – some utilities have funded work on ozone, but our Californian utilities are not
doing well so I don’t think they will fund anything
Juming – how about EPA?
Beth – they have fellowships, and that option can be good for employing a graduate
student. Our program could possibly fit in as a methyl bromide alternative. After all,
non quarantine treatments are going to lose methyl bromide in the next 2 years, and
that includes walnuts to Europe
Jim – because of the exception having now been made for quarantine use, some of
our industry people are no longer concerned, they are likely to become complacent
Beth – well, our industries are interested. For example, the cherry industry was keen
even though we hadn’t had good results in the past. Some years ago they backed out
of funding this sort of project but now they are interested after all
Beth – anyway, big funding does not come from commodity groups, those groups are
quite tight, it is better to focus on government funding
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Jim – What about the annual report Juming needs from us?
Juming – it should be a short paragraph on what you are doing
Juming – I would also like you to send us information on publications, presentations,
reports to industry, posters etc, as they can go onto the web site, along with some
images from the meeting. Please send these to Shaojin by the end of next week.
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Guy – we really need to look into alternative ways of heating, different approaches –
electric shock
Juming – MRI perhaps, like they use for cancer,
Guy – or perhaps a pulsed electric field that targets the CNS of the insect
Jim – if you can stun them, they are more susceptible to other treatments
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Guy – and why couldn’t Strayfield make machines using other systems, they can
make it as well as anyone else. It would be good to have alternatives to RF where
that system doesn’t work
Juming – the problem is that we don’t have base funding, everyone in my group is on
soft money
Guy – we didn’t have to look for soft money up until recently, now we do. That used
to be an advantage of working for the Government. On the other hand, we don’t have
so much freedom to get external projects
Juming – all we get is $700/year – wouldn’t even cover our telephone bill!
Guy – we don’t have enough to cover fixed salaries at the moment, something’s got
to give eventually
Juming – Our University administration takes 46% of our funding Guy – wow, our
Department takes 11% Beth - UCD charges 66%, unless it’s a Federal grant in which
case they took 30%. With industry grants we usually suggest to the company that
they should make a donation. That means there aren’t strings attached, they don’t get
IP and they have to trust you, but it makes it lots cheaper. If the company wants the
report to be confidential they have to pay 66% extra along with lots of other monies
which cover things like my salary, the building costs etc
Guy – we should work on killing anthrax
MEETING OVER
Initiative for Future Agriculture and Food Systems (IFAFS)
First Discussion in Dec. 2000 at WSU and revised in Oct. 2001 at UC Davis.
A. We agreed upon the following objectives (progresses indicated in bold):
1) Delineate the kinetics of thermal mortality for codling moth* (Cydia pomonella (L.))
(James, Juming), two spotted spider mites (Tetranychus urticae) (James, Juming),
Mexican fruit fly (Anastrepha ludens (Loew) (Krista, Guy, and Juming), navel
orangeworm*, (Amyelois transitella (Walker) (Judy, Juming), Indianmeal moth*
(Plodia interpunctella (Hübner) (Judy, Juming), apple maggot (Rhagoletis pomoneela
(Walsh)(Guy, Juming), to establish treatment parameters for pest control – Juming
and all.
* -- near completion in 2001.
2) Investigate the heating of commodities with electromagnetic energy to design
effective energy-delivery methods. This will include measurement of the dielectric
properties of the commodities and insect pests* (Juming), heating uniformity
(Beth, James, Guy, Juming), computer simulation (Juming), and pilot-scale
experiments (Beth, James, Guy, Juming). * in progress.
3) Delineate the thermal response of cherry* (Steve, James & Beth), apple (Steve,
James and Beth), walnut (Beth and Juming), almond (Beth and Juming), pear (Steve
and James), grapefruit, oranges and mango (Guy) to various temperature exposures
(water bath studies) to determine the thermal tolerance range for each representative
commodity – surface tolerance studies. * Cherry started in 2001, walnut and almonds
completed in 2001.
4) Develop treatment protocols to control insect pests and minimize detrimental thermal
effects on the products –; WSU develop protocol* and Yakima, UC Davis, and
Weslaco do validation studies (infested fruits, quality studies – done for walnuts).
*Ready for nuts.
5) Conduct preliminary studies in packing houses to examine efficacy and practicality of
treatment protocols under commercial conditions. Information from these tests will be
used in later research for refining commercial treatments.
6) Promote technologies generated by this research through demonstration projects,
educational workshops, training sessions, multi-media presentation at industry
conferences. Develop a website* to provide current information. * in progress.
B. We defined the work that need to be done in the next two years
Tasks
Objective 1:
Determine the
kinetics of thermal
mortality of insect
pests
Year 1 (2001)
WSU and Fresno, navel orange worms, Indianmeal moth
Near completion
WSU and Yakima, codling moths, completed
Fresno, navel orangeworm eggs tests done in Fresno (bring heat
block to Fresno), provide diapausing Indianmeal moths asap –
moving lab in March, should plan tests before that (Start Indian
meal moths between Jan. 15 and Feb. 15).
Conducted as scheduled, except for eggs.
Objective 2: Study
heating patterns in
commodities
WSU, Design and work on contract for the RF pilot system.
Details circulated among Wapato, Fresno, and Weslaco.
Juming visited Strayfield in March, orders for RF units placed in
May, RF units shipped in October. Training session provided by
Strayfield in Oct. at UC Davis.
Year 2 (2002)
WSU and Weslaco: work on apple maggot,
Mexican fruit fly, eggs, and 3rd instar
(compare among different species).
WSU and Wapato: spite mites (one stagediapausing), bring heating block to Wapato
(one week). Cherry fruit fly (depending on
additional funding)
WSU and Parlier: Navel orange worm eggs
at Parlier (move heating block to Parlier)
Different stages of Indian meal moths
(WSU), compare cultivated and field navel
orange worms.
WSU study means to provide heating
uniformity in RF systems for various fruits
(cherries, apples, pears, citrus and mango) in
collaboration with Weslaco, UC Davis and
Wapato.
Weslaco, Provide fruits (40 lb) and insects for dielectric testing,
install RF unit (late months of the year).
Weslaco provided fruits as planned, insects were not provided
pending permit for WSU quarantine facilities.
UC Davis, provide fruits to WSU for dielectric property
measurement. Install RF unit (late months of the year).
Objective 3:
Determine the
thermal response of
representative
commodities
Wapato, purchase and test the first pilot RF unit
Fresno, provide fruits and insects to WSU for dielectric
properties testing.
WSU - Surface treatment
WSU built two water circulation systems and shipped to
Wenatchee and Yakima in March 2001.
Wenatchee, Wapato and UC Davis, conducted surface heat
treatments of cherries (two cultivars)
Wenatchee completed one season study on cherries (Bings and
Sweetheart).
Weslaco, citrus fruits and mango (water bath
tests)
UC Davis, cherries and pears (water bath
tests), almond (RF treated), walnuts (RF
heated) into long term storage.
Wapato + Wenatchee,
Cherries (two cultivars) and apples (fuji and
Red Delicious, and more) (water baths)
Objective 4: Develop
treatment protocols
WSU, Cherries, Nuts
Completed protocol development
for inshell walnuts
UC Davis, Nuts
Conducted sensory evaluation
studies on walnuts treated at WSU,
hot water treatments of cherries.
Wapato, Cherries,
Worked on water bath treatments
with promising results.
WSU Refines protocols for inshell walnuts (using
5th instar navel orange worms as target pests)
WSU starts tests on almonds and pistachio (navel
orange worms).
UC Davis, sensory evaluation studies on almonds
and pistachio(?). RF treatment of cherries
Wapato and Wenatchee, sensory and quality for
cherries (water or RF, or both ?)
Fresno, Provided insects for
mortality studies, and provided
inshell walnuts infested 5th instar
naval orange worms
Wenatchee, helped Wapato on
water bath treatment for cherries.
Developing quality curves for
cherries (1st year work done)
Objective 5: Conduct
field tests
Objective 6: Promote
the technologies
through
demonstration,
workshops, training
sessions, website
WSU, develop a website
Shaojin developed a website, need a list of
publication and presentation for 2001.
Annual Meetings for IFAFS Project:
WSU, WA, Dec. 2000
UC Davis, CA, Oct. 2001
Parlier (Fresno) CA, Oct. 2002
Wapato, WA Oct. 2003
General comments (Juming):
Hope that the results will not only be useful for RF or MW based treatment, the research
should provide sound fundamental information for thermal treatments in general, e.g., 1).
Comparing heat resistance of insects at different life stages, among difference species, lab
reared and wild. 2) kinetics for thermal resistance of insects as affected by heating rates,
CA conditioning and pretreatment conditioning; 3) kinetic information on thermal
response of fruits to heat treatments – start with surface responses (using heating bath
method); 4) general science based strategies for developing thermal treatments (including
RF and MW).
Publications and Presentations in 2001
Articles in Press
Wang, S., Tang, J., Judy A. Johnson, Hansen, J.D. 2001. Thermal death kinetics of 5th
instar navel orangeworm (Lepidoptera: Pyralidae) larvae. J. Stored Products
Research (proof in October, 2001).
Wang, S., Ikediala, J., Tang, J., J Hansen, J.D. 2001. Thermal death kinetics and heating
rate effects for 5th instar codling moth larvae (Cydia pomonella (L.)). J. Stored
Products Research (proof in October, 2001).
Articles in Preparation
Judy A. Johnson, Wang, S., Tang, J. 2001. Thermal death kinetics of 5th instar Indian
meal larvae. J. Entomology (90% complete).
Wang, S., Tang, J., Johnson, J., Mitcham, B., Hansen, J. 2001. RF treatment protocols for
insect pest control in inshell walnuts. J. Postharvest Biology and Technology
(draft completed on September 20, internal review).
Presentations
Mitcham, E., Tipping, C., Simpson, T., Tang, J., Hansen, J., Bower, J., Biasi, B.,
Johnson, J. 2001. Control of arthropod pests for harvest using CA, GRAS
fumigants or radio frequency heating. Symposium on Recent Trends in Drying
and Storage Technologies for Foods and Agricultural Products, November 3,
2001, Seoul South Korea.
Johnson, J., Wang, S., Tang, J. 2001. Thermal tolerance of navel orangeworm and indian
meal moths. Methyl-bromide Alternative Annual Conference, San Diego, CA,
November.
Wang, S., Tang, J., Hansen, J.D., Mitcham, E., Drake, S., Hallman, G. 2001. RF
treatments as alternatives to chemical fumigation for insect control in nuts.
Methyl-bromide Alternative Annual Conference, San Diego, CA, November.
Buranasompob, A., Tang, J., Mao, R., Powers, J.R., Clark, S., Swanson, B.G. 2001.
Lopoxygenase activity in walnuts and almonds, 49C-4, presented at the IFT
Annual Meeting, June 23-27, 2001, New Orleans, LA.