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June 24, 2016, Guelph, Ont – An all-natural spray, developed by University of Guelph researcher Jay Subramanian and his team of scientists, could do wonders to reduce food waste and enhance food security by extending the shelf life of fruit by up to 50 per cent.
The spray uses a nanotechnology-based application of hexanal, a natural plant extract that prevents fruit spoilage. READ MORE
January 7, 2016, Orange, CA – New research reveals that irradiation can also be effective for treating blueberries and grapes for export without compromising fruit quality.
It is often necessary to treat produce for insects in order to transport crops out of quarantine areas. Fumigation with methyl bromide, one of the most common treatments, is in the process of being phased out because of its depleting effect on the ozone layer. Alternately, ionizing irradiation at low doses is being used worldwide as a promising phytosanitary treatment for fruit such as guava, rambutan, and mango.
Star, Jewel, and Snowchaser blueberries and Sugraone and Crimson Seedless grapes were irradiated at a target dose of 400 Gy (range of 400-590 Gy for blueberries and 400-500 Gy for grapes) and stored for three and 18 days under refrigeration, plus three days at ambient temperatures.
"This experiment was designed to simulate the time of ground transport (from California) to Mexico and sea transport from California to Asia," the scientists explained.
The fruit was then evaluated for soluble solids concentration, titratable acidity, and weight loss. With respect to these quality attributes, the results showed differences among fruit varieties, but the researchers found treatment effects to be "not significant."
The study also involved sensory tests in which consumers evaluated the fruit on appearance, flavour, texture, and overall "liking."
"Firmness was the primary attribute affected by irradiation for both varieties of grapes, but sensory testing showed that consumers did not have a preference for control or irradiated fruit," the authors said. "However, sensory scores for flavour were higher for the irradiated berries than the control berries after storage, suggesting a decline in quality of the control blueberries with time."
The authors said the research showed that (in terms of quality) irradiation at 400 Gy can maintain blueberry and table grape quality sufficiently to meet transportation, distribution, and storage needs for overseas markets.
"Our results show that both blueberries and grapes have a high tolerance for phytosanitary irradiation and that storage affects their quality more than irradiation treatment," they concluded.
The complete study and abstract are available on the ASHS HortScience electronic journal web site: http://hortsci.ashspublications.org/content/50/11/1666.abstract.
October 7, 2015, Guelph, Ont – It can be a real challenge for farmers to match their supply of fresh fruits and vegetables with consumer demand – especially at the height of the harvest when there is often an excess of fresh produce on the market, which can lower prices to growers.
The new bins, designed for use in cold storage facilities, may help solve that problem by extending the shelf life of perishable crops to give farmers more flexibility with their marketing decisions.
“Reducing oxygen levels slows down the ripening process of fruits and vegetables, and our module is an air-tight container that can store fresh produce in a low oxygen environment,” explains Vincent Nicoletis, general manager of Janny MTCA, the Canadian subsidiary of the product’s French manufacturer, Janny MT.
The storage bin lids contain semi-permeable membranes that release carbon dioxide from the bin while maintaining a small concentration of oxygen inside, and can achieve concentration levels of three per cent for both oxygen and carbon dioxide. The normal concentration in the atmosphere or in a cold storage room is approximately 20.9 per cent for oxygen and 0.1 per cent for carbon dioxide.
Dr. Jennifer DeEll, fresh market quality program lead with the Ontario Ministry of Agriculture, Food and Rural Affairs, is leading a two-year project to test the effectiveness of the modified atmosphere storage bin on Ontario crops.
In 2014, her team worked with asparagus, cherries, plums, apples, and pears, and this year trials are being conducted on blueberries at Blueberry Hill Estates near St. Williams, Ont.
“Overall, we’re finding that the bins do extend the storage life. Blueberries also generally respond well to modified atmosphere storage, so we’re hoping to find the same thing this year with the blueberries as well,” she explains.
For this year’s trial, four of the new bins were filled with blueberries and placed into cold storage. Each week for four weeks, a gas sample is taken from one of the bins to make sure it is providing the expected environment. This bin is then opened and the fruit is removed and weighed before it is taken to a lab to be analyzed for acidity, colour, sugar, juice, firmness and overall quality.
The technology lends itself particularly well to smaller operations with on-farm markets or who sell to farmers’ markets.
For example, Nicoletis says the storage bin will give apple and pear growers more time to sell their crops on the higher value fresh market instead of having to look for wholesale or processing markets.
Growers of crops with a short shelf life, like asparagus, blueberries and cherries, can hold back part of their production to sell at a later date when the price might be higher, but without affecting product quality.
“The main benefit for consumers is fresh, local produce available for longer,” he adds.
The Janny MT module evaluation project has received funding from Ontario Agri-Food Technologies’ (OAFT) Rapid Response to Research Needs program. OAFT is supported by Growing Forward 2, a federal-provincial-territorial initiative.
More information about the modified atmosphere storage modules can be found at www.jannymtca.com.
September 8, 2015, Windsor, Ont – A Canadian company claims it’s leading the race to provide the public frozen tomatoes, green peppers and onions, foods that until now didn't freeze well.
Bonduelle Canada CEO Daniel Vielfaure says his company "has the leap on everyone" when it comes to the production of dehydrofrozen vegetables, a process which reduces the water content in vegetables before freezing them. READ MORE
Uncovered forklift openings and through the “hot” fruit where it warms (purple arrows). It‘s then drawn through the slots in the plywood (red arrows) and upward towards the evaporator coils to be re-cooled. Photo by courtesy of Hugh Fraser, OMAFRA
The key to keeping fruits and vegetables alive after they’re harvested is lowering the temperature of the produce and forced-air cooling systems.
“A lower produce temperature reduces ethylene production, damage from micro-organisms, moisture losses and bruising injury,” says Hugh Fraser, extension agricultural engineer with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) in Vineland.
Three kinds of forced-air cooling systems are available, but the one he likes best for cooling produce packed into bins that have slots in the bottom is the serpentine cooling system. Although this is a simple cooling system, it can be difficult to explain in words, he said.
Specially sized, high capacity fans inside the cold storage unit pull refrigerated air through a specially designed duct that a column of bins in multiples of two are placed against; usually four or six bins high. The duct has slots lined up perfectly with every-other forklift opening of the bin column [bin number two, four and six in the case of a column six bins high]. With the fans operating, the forklift openings of these same bins are covered with a tarp so refrigerated air cannot enter that forklift opening across from the plenum slots.
Because the duct is under suction, these tarps are sucked tightly against these forklifts openings. Refrigerated air is then compelled to enter through the remaining three forklift openings and travel up bins one, three and five, or down bins two, four and six, through the produce via the slots in the bins’ floor. Hence, the name serpentine forced-air cooling.
For each column of bins, atop the plenum wall is one centrifugal squirrel cage fan that draws a minimum of one cubic foot per minute per pound of produce (CFM/lb) at 10 mm of static pressure.
Multiple stacks should be packed tightly together with slots/holes covered on the outer most columns to ensure there is little to no short-circuiting of refrigerated air.
“The outer bin sides can be tarped, but in reality, you don’t get a lot of short circuiting through there and there is little difference in cooling,” Fraser said.
One advantage of this system is that it takes the least amount of floor area per kilo of fruit. The second advantage is that the cooling air travels through the depth of the bin and not the width, which puts less load on the fan and speeds cooling.
“This is very efficient and is the best option for cooling bulk produce before packing,” he said.
The disadvantages are it works only with bins that have a slotted floor and any side vents should be blocked.
“There can also be some short circuiting of air through the top bins. And because the cross-section of the fork lift openings are so small … you have a relatively small area through which to pull air. This restricts how many bins.”
Fraser said going two or three stacks deep would work just fine with correctly sized fans.
So how does it compare to the room cooling method?
An Ontario producer built a serpentine cooling system that Fraser used in a test with pears. In this test, one stack of six plastic bins were cooled the serpentine way and compared with room cooling in three plastic bins sitting in an open area of the cooler surrounded by cold, blowing refrigerated air.
Researchers simultaneously monitored the internal temperatures of pears in both the serpentine forced air-cooling and room cooling systems.
They found the serpentine system cooled the pears five times faster and reached a 7/8 cooling time of 3.6 hours versus 18 hours for the room cooling system. “We were actually very ‘kind’ to the room-cooled pears because if these were packed into a cold storage the way they normally would be, it could be a lot longer than 18 hours. I’ve done tests like this with apples and it can be a day and a half before they all get cooled,” he said.
Fraser identified the six components needed to make a forced-air serpentine system.
Need one squirrel-cage centrifugal fan per column of bins. The fan should be able to draw one cubic foot of air per minute (CFM) per pound of fruit at 10 mm (0.4 inches) of static pressure. This translates into one 3,000 CFM fan for six stacked bins of fruit holding about 500 pounds.
“The good news is that every piece of fruit in these bins is at virtually the same temperature when you are done,” he said.
Be wary of any undue restrictions on the fan due to holes that are too small in the bin, or cross-section of forklift opening. You want about two square feet of opening for every 1,000 CFM of airflow.
“So with a 3,000 CFM fan you would like about six square feet of cross section so you are not choking the fan and putting an undue load on it,” he said.
Most plastic bins used by Ontario tender fruit producers are ideal for serpentine cooling because they have straight side walls, they fit like LEGO™ blocks and have long, slotted floor vents. A full 25 per cent of the area perpendicular to the airflow is open.
Short circuit prevention
“If you want to do this right, you have to make sure the air flows through the produce so you have to make sure there are no spots where the air is going to sneak through,” Fraser said.
Put bins together nice and tight, use bumper pads to fill gaps and cover forklift openings correctly. Use foam on the wall for good seal. Use a static pressure gauge to measure if the system is tight.
Ensure you have enough refrigeration capacity to pull the heat out quickly. The hot air pulled from the fruit is directed toward the evaporator coils where it is cooled, then blown back into the cold storage where it is picked up again by the serpentine system.
Monitoring is simple and tells you how effective your system is. In one particular case, the cold air going into the bins measured at 36 F, while at the fan, the hot air coming out was about 51 F.
“That hot air is about half way between the cold air going in and what the fruit temperature actually is. In this particular case, the fruit averaged about 64 degrees which is close to half way,” he said.
By monitoring the temperature of the cold air going in and the hot air coming out, you can predict when the thermostatically controlled fan should be turned off.
“I can’t emphasize enough that virtually every piece of fruit in that bin [should be] about the same temperature when you are done,” he said.
April 27, 2015, Jalandhar, India – Researchers at the Central Potato Research Station (CPRS) in Jalandhar, India, claimed to have invented a new technique that would ensure storage of potatoes for longer duration.
September 3, 2014 – TOMRA Sorting Solutions recently released its new sensor-based systems to sort and process potato products at Potato Europe.
The company demonstrated the Field Potato Sorter (FPS) and displayed the Halo sorter at Potato Europe, in Bockerode, near Hanover, Germany.
“This is the first successful high throughput optical sorting solution in the industry for unwashed potatoes. The system enables growers, processors and packer companies to lower labour and potato storage costs significantly while raising product quality and yield,” explained Jim Frost, market unit manager, TOMRA Sorting Food.“
"Utilizing unique biometric signature identification technology, the FPS provides a representation of the visible and near infrared spectral zones, which allows it to analyze and identify organic characteristics and compositions of all objects. It can therefore distinguish clumps of dirt, stones, foreign material and rot from potatoes, even those with substantial soil covering.”
Frost said the machine could be used for different varieties and sizes of unwashed potato while process and packer customers can use the data the machine produces for predictive analysis, to achieve purposes such as optimizing production lines.
“The FPS is replacing hard-to-find manpower needed to clean the product stream going into and out of potato storage. The robust, weatherproof and user-friendly system is compact and available in various widths to fit all specific capacities up to 70,000 kilos an hour. The sorting machine is compatible with other potato grading equipment, but can also be used on its own to sort harvested potatoes, before or after storage.”
“Neither will meet their potential without both working successfully together,” he says.
The first step is to evaluate your existing facility to decide if it needs just an upgrade or something different entirely. When evaluating an existing structure, you need to look at its location, the structure itself, its insulation system, its ventilation systems and the controls.
From a location perspective, your operation should be situated near the production point to minimize transport costs, preferably on a road that has 12-month access. Also, it should be located where there is sufficient electrical power supply, specifically three-phase power.
“This is a very important factor,” says Forbush. “Three-phase power is an important piece of the puzzle.”
In terms of size, you need enough rooms to hold each variety. Not only that, but those rooms should also consider the climate that you’re harvesting from. “We want one variety in there, we want to fill that bin in three days’ time, and we want to be able to sell that crop in less than three weeks,” says Forbush.
“If it takes you too long to fill that bin of potatoes, you’re going to have a lot of diversity as far as the harvest conditions that you went through and those are going to come back and cause losses in storage. And losses in storage are losses right across the bottom line.”
When it comes to potato storage, insulation requirements say that you should have an R-value of 45-60 in the ceiling, an R-value of 35 to 40 for the sidewalls, and high to low-density materials from the inside out.
“You don’t want to trap moisture in those walls,” says Forbush. “So what happens is we’ve got a moist, warm environment inside the building. If you let that moisture get into the insulation system it’s going to condense at some point after. If it condenses near structural material, it can compromise it. It’s important that once that moisture moves into the wall it can move out.”
“Why is it that we have a ventilation system in potato storage?” Forbush asks.
Because you want to create a uniform environment, while at the same time maintaining proper potato temperature. You also want to provide oxygen for respiration and remove carbon dioxide from respiration.
A poorly designed ventilation system can cause air to be pulled from and directed to the wrong places in your bin. The result is non-uniform ventilation. There are industry-accepted standards for designing and evaluating ventilation system performance in potato storage. Air takes the path of least resistance, Forbush reminds growers. If you’re not sure whether or not your air is going where you want it to go, measure it. Remember, your ventilation system’s airflow is a function of its design. By quantifying the flow of air through your bin you’ll know just where your system needs improvement.
According to Forbush, a well-designed ventilation system includes these attributes:
- adequate airflow 1.25 to 1.5 cfm/cwt for table stock and process potatoes (25 to 30 cfm/ton)
- inlet and exhaust max of 1,400 ft./min.
- main air plenum maximum of900 ft./min.
- lateral duct maximum of 1,000 ft./min.
- slot duct max of 1,200 ft./min.
For example, here are the calculations for a well-balanced bin:
- Bin size: length = 200ft; width = 50 ft.; pile height = 16 ft.
- 200 x 50 x 16/2.5 = 64,000 - (factor for pile slope) = 60,000 cwt storage
- Fans: Two to 48-inch;15 hp Aerovent = 78,000 cfm
- Airflow equals cfm/cwt:
- 78,000/60,000 = 1.30 cfm
“The key for slot design is the slot design provides that back pressure, which then gives you uniform airflow,” he continues. “So if you don’t have
uniform back pressure, you don’t have uniform airflow.”
Here’s how to determine slot area. If it’s pipe, measure the size, number of rows and distance of holes drilled in the pipe. If they’re flumes, measure the board width and amount of open space between each board. For example, our example: 78,000 / 65 ft^2 = 1200 fpm.
“The other side of slot design is poor slot design can cause a defect called pressure bruise, which is excessive evaporation,” says Forbush. “And even with a proper humidification system, if the slot is designed incorrectly the air can’t carry that water into the potato pile. So poor slot design can also lead to this pressure bruise issue, even with good humidification equipment.”
Creating the perfect potato
The second part of the quality potato storage equation is the potato itself. In potatoes, the factors that affect storage performance include environment, your agronomy, varietal traits, disease and harvest and management practices.
The most important factor in determining storage performance is variety.
“Varietal traits give us a starting point for understanding the strengths and weaknesses of the crop going into storage,” says Forbush. When choosing a variety, look for such traits as yield, specific gravity, sugar profile in storage, bruise resistance and disease resistance.
The next most important factor in determining storage performance is the weather, but that’s something you have no control over. While you have no control over the environment, you do have control over soil conditions and your agronomy.
“Those four things come together to kind of create the fingerprint or the way the genetics are expressed for that
potato,” says Forbush. “Given those four things, you’re then going to determine how those impacted each other, and you do that with what’s called pre-harvest sampling.”
Pre-harvest data is a valuable piece of the “complete picture” of your tubers’ maturity and storability.
“What you’re trying to do is figure out how those four main pieces came together in any given season and then determine what the best storage practices are given the way those four variables impacted the crop’s genetic expression.”
Finally, in order to implement these ideas on your operation it’s important that you have great communicate with your staff.
“If your staff members do not understand operations goals, they cannot help achieve those goals,” says Forbush. “Identify areas where improvements in your storage facility and storage management practices can help achieve
Crown rot is typically a storage disease of carrots. But MacDonald discovered an outbreak of the disease in the field while working as an Agriculture and Agri-Food Canada (AAFC) field researcher.
According to MacDonald, the fungus first started appearing in P.E.I. carrot plantings in 2011, resulting in rejection rates as high as 60 to 70 per cent of the crop at grading. While some carrots were salvaged by cutting them into smaller sizes, the majority were unmarketable as regular sized vegetables.
Crown rot traditionally appears after harvest, triggered by the Fusarium fungus, said MacDonald. Fusarium can overwinter in the soil and enters the carrot through cracks in the crown of the vegetable.
Initial studies identified F. acenaceum and F. oxysporum as the fusarium populations infecting the P.E.I. carrots. F. acenaceum was highly pathogenic to carrot tissue while F. oxysporum was less sensitive.
During her research, MacDonald tested two Fusarium pathogens: 10 isolates of F. avenaceum and four isolates of F. oxysporum. Each isolate was tested – in replicated trials – against five different fungicides: Bravo (chlorothalonil), Manzate (mancozeb), Polyram (metiram), Pristine (pyraclostrobin/boscalid) and Quadris Top (azoxystrobin/difenoconazole).
Nine different treatment applications were used (eight with fungicides and one control) during the trial and there was also monitoring for the occurrence in the carrot crop of Sclerotinia (white mold) and two leaf diseases – Alternaia leaf blight and Cercospora – MacDonald said.
While it was observed that all the treatments decreased Sclerotinia and provided foliar protection from Alternaia leaf blight and Cercospora, there were no treatments that significantly decreased crown rot in the field, she said.
In the lab, both Fusarium species proved insensitive to Mangate. Quadris Top had a big range of response in the lab, with greater sensitivity in F oxysporum. F avenaceum was insensitive in fungal response trials in the lab to Bravo; but F. oxysporum showed a little bit of sensitivity. Pristine and Polygren have yet to be tried for fungal response in the trials. MacDonald stated that in the lab, F avenaceum showed some sensitivity to Fludioxonil, although F. oxysporum did not. Both Fusarium funguses demonstrated a sensitivity to Thiabendizole in the lab trials.
Difenoconazole was predicted to be a successful treatment, but the lab results showed otherwise, said MacDonald.
Scholar demonstrated an effect on white mold, but MacDonald cautioned there are concerns with resistance.
She added that the crop can be scouted for crown rot but, after the infection appears, it is too late to spray. A preventative spraying program before infection appears would be the best management option.
"We thought that if we could cut apples and put them in a bag, we could compete with baby carrots – but the apples would always turn brown," says Carter, president of Okanagan Specialty Fruits (OSF), an agriculture biotechnology company in Summerland, B.C.
Carter founded OSF 17 years ago and has been working on solving that problem ever since, but may have finally figured it out thanks to a process entitled "gene silencing." These new types of apples, known as Arctic Apples, have won the 2013Golden Leaf Award from BIOTECanada for innovation in developing a new product.
"There's potential with what we're doing to create jobs and work for Canada," says Carter. "Winning the award lets me know that we are on the right track."
Arctic Apples are not the first apples on the market to boast reduced browning, they are the first that claim to never undergo enzymatic browning. "It's all-or-nothing," he adds. "Ours is all."
Enzymatic browning can occur very quickly once an apple has been cut and left out, and is what turns many people away from apples. The reaction is caused by the enzyme polyphenol oxidase (PPO). When bruising, biting or cutting ruptures an apple's cells, the browning process begins when the PPO in one part of the cell quickly reacts with compounds in other parts of the cell, causing the flesh to brown.
OSF claims that the new Arctic Apples prevent enzymatic browning, not bacterial or fungal. "A rotten fruit is still a rotten fruit," says Carter. "Bacteria have its own separate enzymes that we are not dealing with."
Carter says that the apples grow the same, flower identically and react to pests and diseases the same way any apple would. "They are exactly identical to the parent apple until you slice them open and see that they don't brown," he says.
Currently the only kinds of Arctic Apples the OSF has developed are the Arctic Granny and Arctic Golden – but they are currently in the process of developing Gala and Fuji varieties.
There is some concern about adding another genetically modified food to the market, but it doesn't discourage Carter and his team. "Like any genetically modified food being introduced there is bound to be some controversy," says Carter. "We like to think that what we've done is quite inoffensive, it's in every way still an apple, the same apple that consumers have always enjoyed, it just doesn't brown."
Although the OSF is still waiting on the regulatory approval process to be completed before Arctic Apples make it to grocery stores, Carter is hopeful to have the regulatory process approved in the U.S. by this fall and Canada by the end of the year. In the meantime, OSF is continuing similar studies for preserving cherries and peaches.
BIOTECanada presented the Golden Leaf Award to the OSF at the 2013 BIO International Convention in Chicago, Illinois on April 23, 2013.
September 14, 2012 – Sonoco, a global packaging company; Paper Pak Industries, a manufacturer of absorbent mediums for the food industry; and Bunzl Distribution, a global packaging and supplies distribution company, recently introduced the UltraFreshSystem for packaging fresh-cut produce.
The tray includes an insert to channel liquid away from the product while the food safety pad absorbs excess moisture inside the package and emits a steady stream of carbon dioxide, reducing the growth of microorganisms such as yeast and mold. Together, the tray and absorbent pad maintain the appearance of the fresh-cut product and extend shelf life by slowing the produce’s respiration rate. The result is a fresher, firmer product through the use-by date.
“The UltraFreshSystem is a cost-effective package that delivers superior merchandising appeal and extended shelf life,” said Rodger Fuller, vice president of Global Rigid Plastics at Sonoco. “Produce processors can also count on less shrink, better margins and reduced packaging costs.”
The design of the tray lowers stacking height, increasing shipping density and reducing costs for shipping and storage. The tray’s composite surface also results in a faster seal at lower temperatures compared to other trays in the marketplace, which minimizes the risk of cross contamination and operator liability. And because it is made with less plastic, the custom-designed tray creates less waste and a smaller carbon footprint.
November 29, 2011 – An inflatable temporary storage developed by a north Norfolk, UK, potato business could slash costs and create new opportunities for growers.
Agriculture and Agri-Food Canada (AAFC) researchers in Kentville, N.S., are seeking remedies for disorders that continue to plague Honeycrisp.
Two of the disorders are soft scald on the skin and an internal condition known as internal breakdown or low-temperature breakdown, explains Dr. Robert Prange.
Dr. Prange, a specialist in post-harvest physiology at the AAFC’s Atlantic Food and Horticulture Research Centre (AFHRC), says internal breakdown is a condition that can’t be detected on a packing line because it has no external indications.
Previous research by AFHRC researchers on fruit storage has determined that internal breakdown and soft scald are problems related to delayed cooling. They have demonstrated that the two conditions can be successfully controlled by delaying cooling of the apples for six days after picking, keeping the fruit at 20 C. After the six days, the Honeycrisp can be placed in controlled atmosphere (CA) storage.
Conversely, if the apples are cooled in conditions of less than 20 degrees for less than six days, the door is opened to problems, notes Dr. Prange.
He says AFHRC researchers have shown if they pre-cool at 25 or even 30 C, the pre-cooling storage period can be shortened to as little as just one day at 30 C.
This, however, creates “a logistical issue,” concedes Dr. Prange, because storage operators need to find a source of heat, “and storages are not made to be heated.”
There was also some concern that at 30 C there might be moisture loss from the fruit, but Dr. Prange notes very little moisture is lost in just one day.
They have learned, however, that delayed cooling will not stop either bitter pit or senescent breakdown (late storage complex), he says.
Senescent breakdown appears as a subcutaneous, differential browning of the apple cortex, while bitter pit is a calcium deficiency well known in Honeycrisp grown in other regions, Dr. Prange says.
Senescent breakdown was particularly noticeable in the Annapolis Valley during the 2009 crop storage season, “but we feel it has been there in other harvest years and other Honeycrisp growing areas,” he says.
Bitter pit appeared during the first four weeks of the harvest, was quiescent during the fifth week, and after the fifth week it was replaced by senescent breakdown, Dr. Prange says.
In the 2008 and 2009 harvest seasons, AFHRC researchers ran a 10-week sampling program, he says, noting the term “senescent” implies the fruit is older and over-mature and may be related to late picking. Dr. Prange says fruit from orchards in all weeks of the sampling program was stored for three months without delayed cooling and they found a substantial increase in senescent breakdown in late-picked Honeycrisp.
These observations suggested that there was an optimum picking period when these two disorders were least likely to occur, states Dr. Prange.
“Therefore, in order to reduce the occurrence of bitter pit and senescent breakdown we have to get more precise data on what is the optimum picking window.”
According to the 10-week harvest samples from 2008 and 2009, Honeycrisp fruit from the fifth harvest, which was closest to the optimum harvest time, had fruit internal ethylene content of about 2.88 ppm, a 5.37 starch index and red colour development of about 68 per cent, says Dr. Prange.
With fruit held in a refrigerated air (RA) storage of 3.5 C, bitter pit appeared in early harvested fruit from week one to week five, he says. In fruit harvested later – week five to week 10 – senescent breakdown occurred.
As a result, Dr. Prange believes the period from week five to seven is “the optimum harvest window. We seem to be getting a handle on the optimum harvest week.”
The optimal picking date in 2010 – averaged over eight orchards – was Sept. 27, several weeks early than 2009, says Dr. Prange.
In 2010, weekly samples were again taken and this time he included measurements from a new instrument called a DA meter, which Dr. Prange acquired from its Italian manufacturer. It is being evaluated for its ability to predict optimum harvest by measuring how much green or chlorophyll remains and is active in the fruit skin, says Dr. Prange, adding it is a non-destructive test.
Preliminary results from the 2010 weekly sampling showed that the DA values declined steadily as the fruit matured. As such, Dr. Prange believes a range of DA meter values can be identified that pegs the optimum harvest window and it can be customized for any given orchard.
Dr. Prange also examined the possibility of calcium deficiency since bitter pit and senescent breakdown in many apple cultivars is known to be reduced by increased calcium inputs, as calcium goes where water goes in the tree systems, he says, observing that Honeyrcrisp has very low water permeance, which means that Honeycrisp’s skin tends to retain water inside the apple more than any other apple cultivar.
“That is why it is crispy.”
Poor summer weather may influence calcium deficiency in Honeycrisp as early as July, when fruit cells should be growing rapidly and the cell walls need calcium, Dr. Prange says.
To reduce bitter pit and senescent breakdown, he recommends growers use calcium spray and harvest at the appropriate maturity. They should also clip Honeycrisp stems during harvest to control skin punctures and decay.
To avoid soft scald and low temperature breakdown, he advises growers to delay cooling and “don’t drench. We are not seeing what we want to see with calcium spraying.
“We have trees sprayed with calcium, yet they are showing bitter pit if harvested too early and senescent breakdown if harvested too late. Calcium doesn’t seem to torque it one way or another. One tree may get calcium and have problems. Another may not and be quite happy.”
Fortunately, he notes, even in trees with fruit that developed bitter pit (early picked) or senescent breakdown (late picked), the fruit harvested in the optimum one to 1.5 week harvest window had very little of these two disorders.
As for storage times, Dr. Prange recommends less than four months for refrigerated storages, while apples can be stored for more than four months in controlled atmosphere (CA) storages. CA storages also prevent greasiness on apples.
They can also have a low oxygen level of between 0.5 and 0.8 per cent, he says, while CO2 levels in the first four weeks of CA storage should be kept below one per cent, after which they can rise up to one per cent.
“We are testing several compounds as foliar sprays to reduce disorders and improve flavour,” says Dr. Prange, emphasizing the tests will have to be repeated over several seasons.
He notes this research is funded by the National Research Council, the federal IRAP program and the Nova Scotia government.
On the surface, it might seem pretty difficult to confuse pears with apples. But when it comes to storage, Dr. Robert Prange of Agriculture and Agri-Food Canada (AAFC) states growers need to be reminded of the differences between the two tree fruits.
Dr. Prange, a post-harvest physiology researcher with the Atlantic Food and Horticulture Research Centre, states growers must remember there are a great variety of treatment protocols for the various pear cultivars.
“We must recognize our pear industry isn’t large enough to demand a lot of research on it,” he emphasizes.
Growers can make money with pears, Dr. Prange says, but pears take longer as an orchard system to come into production than apples.
“Plant pears for your heirs,” he recommends.
The key to storing pears is firmness, which is determined by the pears’ maturity and time of harvest, explains Dr. Prange. Pear firmness declines during maturation and post-harvest pear quality is dramatically affected by temperature. All pear varieties should be air stored below 0 C, he adds.
He also notes the storage life of d’Anjou and Bartlett pears will be 35 to 40 per cent longer at -1 C than at 0 C. A delay in cooling post-harvest will also shorten the storage life of pears. Immediate cooling of Bartlett pears will result in very little core breakdown, says Dr. Prange.
“If you wait two weeks, you will get 100 per cent core breakdown.”
The quicker the pear core gets down to a temperature of -1 C, the more pear storage problems will be prevented, he says.
“You want high humidity in the storage,” says Dr. Prange, adding pears can quickly lose moisture.
With low storage temperature; however, it is difficult to achieve this balance. He recommends growers consider polyethylene bin liners, “if they can be combined with good temperature control,” he adds.
Dr. Prange stresses that pear ripening is different from ripening in apples. Most pear cultivars require cold storage at -1 C before they will ripen normally at room temperature.
Cold storage time at -1 C varies for each cultivar, he says, with Bartlett taking only two to three weeks, Bosc four to five weeks and d’Anjou seven to eight weeks.
The best ripening temperatures are between 15 and 21 C, says Dr. Prange, adding consumers must also let the fruit set for a short period at room temperature for the final ripening process to get the best flavour and texture for the fruit.
There are also fewer post-harvest chemicals, he notes, for pears than for apples. 1-MCP (Smartfresh) is not recommended for pears, as it stops ripening. Scald control chemicals are also no longer available in Canada and, although DPA scald control (currently used on apples) is allowed on pears at 0.1 parts per million (ppm), it could soon lose European Union approval, Dr. Prange says. Superficial scald on d’Anjou can be controlled by delaying ripening, while pink end in Bartlett is caused by cold temperatures in the orchard before harvest and is triggered by ethylene in storage and by ripening. Senescent scald and core breakdown (core rot, brown heart or mealy core) are caused by over-mature fruit and friction marking by rough handling, he adds.
Controlled atmosphere (CA) storage is recommended for pears but the CO2 level must be kept below one per cent, lower than CO2 levels for apples. Dr. Prange says the incidence of core browning, senescent scald and internal breakdown are also reduced by CA storage.
CA stored pears maintain high quality much longer than regular air (RA) stored fruit, and disorders, such as scald and internal breakdown, are reduced, Dr. Prange says. DCA (dynamic controlled atmosphere) storages can store fruit at an oxygen level as low as 0.4 per cent and the method also offers maximized pear quality over CA storage, he says. Bartlett stored six months in CA had a core breakdown of 15 per cent compared to just four per cent in DCA storage, while d’Anjou stored eight months in CA had 12 per cent superficial scald compared to zero per cent in DCA.
Dr. Prange says both DCA and CA reduce friction marking, but there is high maturation in CA compared to DCA.
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2017 Muck Crops ConferenceWed Apr 12, 2017 @ 8:00AM - 05:00PM
2017 Canadian Produce Marketing Association ConventionTue May 09, 2017 @ 8:00AM - 05:00PM
2017 Potato Growers of Alberta Golf TournamentThu Jul 06, 2017 @ 8:00AM - 05:00PM
18th Annual Enology & Viticulture Conference & Trade ShowMon Jul 17, 2017 @ 8:00AM - 05:00PM