Importance of Managing Humidity and Temperature from Harvest to Packinghouse

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Importance of Managing Humidity and Temperature from Harvest to Packinghouse

Peter M.A. Toivonen peter.toivonen@agr.gc.ca

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Importance of Managing Humidity and Temperature from Harvest to Packinghouse “Experience with sweet cherry�

Contents Introduction

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Experience with sweet cherry

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References

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Comercial Information AgriCoat

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Agro Technologie

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Maf Roda Agrobotic

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Introduction The time from harvest to delivery of fruits and vegetables to the packing facility can be the most critical in determining potential quality at the market place. While focus is placed on cooling or keeping the fruit or vegetable cool, often little thought is placed on the importance of relative humidity. Temperature and relative humidity are of equal importance, particularly for prevention of water loss. We have conducted research over the years looking at approaches to managing fruit and vegetable temperature and humidity immediately after harvest and during transport to the packing facility. The results have been consistent in that quality can be best maintained only if both humidity and temperature are managed together and this has be found important for fruits or vegetables that would be sold as fresh or for processing.

Experience with sweet cherry The discussion will focus on experience with sweet cherries. In the past, it was recommended that sweet cherries be covered with wet foam pads after harvest in the field. However that practice is cumbersome, can be unreliable and lead to decay problems in the fruit. Others have suggested in-field hydro-cooling, however that is an expensive approach.

In British Columbia we adapted an inexpensive technology that was previously developed to cover and protect forest tree seedlings prior to planting in remote mountainous areas. The reflective tarpaulin (Silvicool tarp) has been used for several decades by the tree planting industry (www.bushpro.ca) and we have tested this extensively for use in herbs, vegetables and tree fruit. We do not specifically endorse this product since there may be similar products available in other jurisdictions. The tarpaulin is made in a three layer construction, the inner layer (facing the produce) is a silvered Mylar™, the core is a standard woven polyethylene tarpaulin material and the outside is a bright white coating (Photo 1). The result of covering produce with this tarpaulin is that a condition equivalent to deep shade in a forest is created (i.e. cool with high humidity).

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Photo 1. Left shows the inner silvered layer facing cherries and outer white layer facing the sun. Note that the tarps are attached to bins at edges with Velcro fasteners. Photo on right shows bin after filling with cherries and prior to transport to packing house.

Stem browning was one of the most important marketing issues over a decade ago for sweet cherries. The stems of cherries are long and thin, having a high surface area to volume ratio. This means that the stems are much more susceptible to water loss than the fruit which have a low surface area to volume ratio – i.e. the fruit are almost a perfect round ball shape. In our initial evaluation of the problem we determined that stem browning was largely associated with the time from harvest to delivery to the packing house. Most browning was visible within one day after packing. Covering the fruit with the Silvicool tarp resulted in the fruit maintaining the fruit harvest temperature and the humidity quickly rose to 100 percent around the fruit. In fruit that was uncovered or fruit covered with cardboard or conventional tarpaulins, the temperature rose steadily until delivery to the packing house and the humidity declined (Figure 1). Stem browning was eliminated by covering with the Silvicool tarp (Figure 2) and fruit quality was also better retained in storage (Photo 2). In work done in Washington State, it was found that the Silvicool tarp was much more effective at controlling cherry temperature than the wet foam pads used by some orchards in that state.

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Figure 1. Cherry core temperature and humidity at 3 inches below the top of the surface of the fruit for cherries covered with a reflective 'Bushpro' tarp or for uncovered bins held under tree shade.

Figure 2. Stem browning on cherries either uncovered or covered with reflective 'Bushpro' tarp at harvest and either hydro-cooled or air-cooled before storage.

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Photo 3. Visual quality of cherries after 4 weeks storage at 1 ° for fruit left uncovered or covered with reflective 'Bushpro' tarp.

Since cherries are hydro-cooled, there was some thought that perhaps hydro-cooling could reverse any damage to the stems or fruit by virtue of “adding water back” to the product (Figure 3). However, in our experiments we showed that once the water loss had occurred, the injury caused (particularly for the stems) could not be reversed (Figure 2).

Therefore the adage “an ounce of prevention is worth a pound of cure” is appropriate to this discussion. It is also worth adding a comment about the hopes that packaging can help control problems such as stem browning in sweet cherries, but the reality is that if the fruit are not protected immediately after harvest and until delivery to the packing house no sophisticated package will undo this injury. It is essential to care for the fruit at the harvest stage onward to obtain any incremental benefit offered by packaging for transport and distribution.

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Figure 4. Stem browning on cherries either uncovered or covered with reflective 'Bushpro' tarp at harvest and either hydro-cooled or air-cooled before storage Similar benefits have been found with the use of reflective tarps for blueberries (fresh and processed), broccoli and fresh herbs. Controlling temperature and humidity at harvest and during transport to the packing house is a difficult challenge. Product exposure to heat of the sun and low humidity will cause excessive initial water loss and injury that cannot be reversed by any subsequent postharvest handling procedure. That initial water loss and injury results in lost shipping and shelf life potential that is seen by the buyer and consumer. Use of reflective tarps to prevent solar heating and to surround the fruit or vegetable with high humidity is an inexpensive and reliable approach to ensuring maximal shipping and shelf life potential for almost any fruit or vegetable. The use of reflective tarps is now a general practice with BC growers who export their sweet cherries around the world.

References Joanne Schick, and Peter M.A. Toivonen. 2002. Reflective Tarps at harvest reduce stem browning and improve fruit quality of cherries during subsequent storage. Postharvest Biology and Technology 25:117-121.

P.M.A. Toivonen, P.J. Delaquis, S. Stan, and K. Stanich. 2004. The use of reflective tarps at harvest to improve postharvest quality of blueberries. Canadian Journal of Plant Science 84: 873-875.

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Importance of Managing Humidity and Temperature from Harvest to Packinghouse

Peter M.A. Toivonen peter.toivonen@agr.gc.ca

Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, Summerland, British Columbia, Canada V0H 1Z0

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Semperfresh, to maintain the quality during storage and enchance shelf life in sweet cherries Semperfresh is a sucrose ester based coating used widely in the fruit industry, but particularly on sweet cherries to maintain quality during storage and enhance shelf life. Semperfresh has been applied by some of the larger cherry growers/packers in the US and South America for some years, and now other important cherry producing countries such as Turkey are following the trend.

The coating creates a selectively permeable film that inhibits water loss while allowing gas exchange between the fruit and its environment. The modified atmosphere created by Semperfresh reduces weight loss and excess respiration, resulting in firmer cherries with less pitting. Cherry stems stay greener and softer and are retained by the fruit longer due to greater moisture retention. The product can be applied by dip tank, flume, drench, or spray application, and can be mixed with all commonly used fungicides.

Where Modified Atmosphere Packaging (MAP) has been replaced by ‘clamshell’ packaging (non MA), which now makes up much of the market, the use of Semperfresh has been found to be essential for maintaining quality. Semperfresh maintains cherry quality in clamshells significantly better than clamshells alone. Semperfresh has shown benefits similar to MAP in commercial trials. Where the best fruit is required, Semperfresh can be used in combination with MAP to give an improved quality product and helps especially in maintaining quality once the product is removed from the MA pack.

Semperfresh plus MAP liners results in fruit quality superior to either method alone.

Trials in collaboration with a UK cherry grower compared untreated and treated Sweetheart variety cherries destined for supermarket sale.

The objective of this trial was to assess any improvement in quality, particularly during supermarket shelf life (after removal from MA), which might be achieved through treating cherries with Semperfresh.

Cherries were picked and transferred the same day to the packing line, where they pass through three isolated baths or flumes, for washing and hydro-cooling. The final bath was dosed with the recommended concentration of liquid Semperfresh. Fruit was packed, 6 kg at a time, into MA liners onto open plastic trays and were transferred to the cold store for a couple of weeks. After a seventeen day storage period, the fruit was removed from the MA liners and packed into smaller plastic clamshell punnets (non MA) for sale.

The first chart below gives detail of the samples held in MA box liners for 17 days. The second chart is on fruit that was then held in clamshells for 7 days after the initial 17 days in MAP (blue, the control; lilac, MAP; clear, MAP + Semperfresh)

The following benefits over and above those seen with MA packaging alone, were observed in fruit treated with Semperfresh in combination with MA packaging -

Increased shine, which was not lost over time.

More uniform colour, with fewer very dark fruit, which was maintained after the fruit were removed from MA. Less dehydration after removal from MA. Firmer fruit, particularly after removal from MA. 5)Greener stems, particularly after removal from MA.

Hugh Douglas, Regional Sales Manager. AgriCoat Natureseal Ltd, Mantrose UK Ltd. Granada, Spain, hugh.douglas@agricoat.co.uk, Tel: +44 (0)1488 648988

Agro Technologie – Instruments for cherries AGROMORPHA®2 is a dendrometer / biomorphographer.

If has 2 functions : Register each 10 seconds to each 15 minutes a tree branch diameter Register ambient temperature For making its photosynthesis, a plant absorbs water through its roots, and losses water through its sheets. As far as the plant losses more water than it absorbs, it uses its own reserves. And the size of the cells is decreasing. This small variation is registered by AGROMORPHA®2 It is a very good toll for agronomic research. You can determine the effect of watering, or the contribution of a fertilizer.

You have the possibility to follow this diameter continuously during 2 years without changing the batteries. Then you can determine whether the growth of the tree, fruit or corn was regular, and whether the plant has suffered Advantages compared to existing products : Very small Battery capacity 2 years (Standard battery to be changed after 2 years) Registering capacity 2 years You just put a Usb key, and all data is transferred to an Excel file You do ’t ha e to re o e the syste The usb key is automatically detected, and the transfer of data is automatically made – The data in the internal memory is automatically deleted Up to 16 systems can be put in a field, the Excel files on your key have the numbers 1 to 16 It takes a few seconds to collect the data AGROSTA®100Field (Durofel) is a portable durometer firstly designed for tomatoes. Many other uses have been found like firmness measurement of apricots, plums, blueberries, cherries, olives, peppers, peaches, strawberries... As well as fruits in sugar sirup, jelly... It measures the firmness through a mobile tip that gives a unit each 0.025 mm (Measurement of the deformation of the fruits when pressed by the tip) - It is a very accurate device, calibrated through a process defined by the national tests laboratory The AGROSTA®100Field displays the measurements one after each other without pressing any button.

Data is registered for each batch, and the device gives instantly the average and standard deviation The latest innovation from the creators of the "DUROFEL" connected to a tactile console with 32GB memory, the AGROSTA®100Touchscreen measures the firmness of softskinned and soft fruit. It stores and analyses a huge amount of data. It is the most technologically advanced instrument on the market to measure fruit and soft and semi-hard materials No more manual caliper, no templates.... Your fruits cross the door, their size is automatically registered. The data is classified by batch names The software proposes complete database management (delete old batches, rename batches, export to Excel, print, display comparative graphs...)

The device is proposed in 2 main versions : Agrosize®X which has to be connected to a computer, and is provided with a software compatible with Windows Vista, Millenium, XP, 7 and 8 Agrosize®Touchscreen which is a portable device, autonomous with 2 batteries. Memory : 32 Gb, embedded with an Intel processor, resistive touchscreen, stylet. The tablet is working under Windows 7 operating system (Same software as the X version) - But you do ’t ha e to use i do s Which is hidden by the Agrosize software, starting automatically when you switch on the tablet - Closed automatically when you switch off the tablet)

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