Apple growers are faced
with a retailer-driven supply and demand. What the retailer demands,
it must be supplied – especially in the shadow of large retailers
like Wal-Mart. And what is demanded is a year-round supply of high
quality apples.
Products like SmartFresh, from AgroFresh, can help extend an apple’s
shelf life. But what if that can be done without chemicals?
Researchers in Canada are saying it can – with HarvestWatch.
HarvestWatch is a sensor and computer-based software system that utilizes
changes in chlorophyll fluorescence to determine optimum storage conditions.
“HarvestWatch is placed over a sample of the apples in a special
box or kennel,” said Robert Prange with Agriculture and Agri-Food
Canada’s Atlantic Food and Horticulture Research Centre. “And
that sensor head has four LEDs with a detector in the middle. Those
LEDs are emitting red light to the surface of the product. If the
product is a fruit or vegetable with chlorophyll in it, the chlorophyll
will absorb the red light. If healthy, a characteristic fluorescence
signature is emitted; if unhealthy, that signature changes. And that
fluorescence is recorded continuously by the detector.”
If the oxygen level in the controlled-atmosphere (CA) room is too
low, the sensor will detect that through the amount of light sent
back to it. This is then recorded on the software that is displayed
on the main computer in the CA computer room, Prange said.
“We’re dealing with controlled atmosphere, and the benefit
of CA, in theory, is storing the product at the lowest acceptable
oxygen,” he said. “HarvestWatch finds that lowest acceptable
oxygen and allows the operator to keep it at that point.”
A representative sample of the apples in storage is used as the measurement
group. They are put in a container with the sensor, and cables running
from the sensor out of the CA room to the main computer carry the
information.
“Generally, in a standard size CA, you’d take four to
six samples (six to eight pieces of fruit in each),” said Michael
Hodgett, vice president of business development and marketing for
Satlantic in Halifax, Nova Scotia, Canada. Satlantic Inc. is the company
that markets HarvestWatch. “You pick it to be representative
of your entire room’s fruit. Every hour there’s a measurement
taken.”
Hodgett said that if the oxygen levels are accidentally too low in
a CA room, the fruit begins to produce a lot of the metabolic products
of anaerobic respiration, which cause off-flavors in the fruit. HarvestWatch
will warn the operator that this is happening, and low oxygen problems
are avoided.
With the sensors running throughout the storage season, the CA operator
can keep a constant eye on the oxygen levels and know exactly where
the threshold level is between healthy fruit and fruit that is not
storing well.
“HarvestWatch has the ability to warn a storage operator that
something is incorrect in the CA instrumentation,” Prange said.
“We have seen numerous examples in our research and commercial
trials where the fluorescence signal was going up. This was caused
by CA equipment malfunction that the operator wasn’t aware of
– HarvestWatch was warning of problems.”
The benefits of HarvestWatch don’t just stop at reducing off
flavors. Among the benefits are firmer fruit and even the reduction
of superficial scald.
“It’s has really good performance when you use it to prevent
scald,” Hodgett said. “That’s the place where there’s
a huge opportunity for people in the organic market because they can’t
use the chemicals…You no longer have to market it (the fruit)
early in order to minimize scald. You can hold your fruit and you
can take it to market when you want to go, not when you feel you have
to.”
“HarvestWatch results in firmer fruit with better shelf performance,
fresher color and scald reduction,” Prange said.
And HarvestWatch isn’t only for apples. It is currently being
used or tested on kiwi, pears, avocados, lettuce, green pepper, cabbage
and mangoes.
Each system costs around $12,000 (U.S. dollars) to set up. That includes
the sensors, software, all the cables, connectors and the support
to get the system up and running. There are even lease options available
on a case-by-case basis.
Hodgett said there are about 30 HarvestWatch systems in use around
the world by researchers and commercial operations.
For more detailed information, call (902) 492-4780 or visit www.harvestwatch.com.
