Current Technology for Fruit Preservation

At the recent Essex County Associated Growers’ Annual Meeting and Trade Show, Jim Schaefer, owner and President of Storage Control Systems Inc. (Sparta, Michigan), spoke on the subject of Preserving Your Fruit for Days and Beyond. He began with a few fundamentals on fruit respiration and then explained the current techniques available to slow down product deterioration. These range from simple refrigeration to modified or controlled atmosphere storage, plus the most recent use of SmartFresh. Storage at low temperature in ambient air is a short-term solution to extend the marketing window, whereas some sort of atmospheric modification is needed for long-term fruit storage.

Modified atmosphere (MA) usually involves the addition of CO₂ and/or reduction of O₂ at the beginning of the storage period, with no further monitoring or active control. The major factor for success with MA is constant temperature, but this is often difficult throughout the cold chain. As such, this type of storage is more common for short-term holding of berries than for long-term storage of apples.

Controlled atmosphere (CA) is the norm for long-term storage of apples. Similar to MA, there is a reduction in O₂ and an increase in CO₂ at the beginning of CA storage, but the atmosphere is then monitored regularly and corrected frequently. In addition to the typical large CA storage rooms used for apples, there are also methods to utilize CA on a smaller scale. In cases where there is a need to place only a few pallets into CA, plastic pallet covers or zipper tents can be used. These can be made for 1 to 48 pallets and have the economical benefit of utilizing an existing cold room. The covers or tents are air tight and hold the CA, so that the cold room itself does not need sealing.

For all CA set-ups, one can choose either manual or automatic gas control, depending on cost preference. Similarly, one can choose between using bottled nitrogen (for reducing O₂), which is often inconvenient and expensive over time, or purchase a nitrogen generator that is customized for whatever the need. Storage Control Systems Inc. (SCS) is the only North American supplier of Permea^TM nitrogen generators. These have the advantage of using hollow membrane fibers, and thus have fewer moving parts, less maintenance requirements, and reduced chance of breakdowns (compared to the pressure-swing type generators). The use of lime to reduce (and maintain) the amount of CO₂ in the CA room versus acquiring a more efficient and convenient carbon scrubber is another chose for the storage operator. The advantage of the latter is automation and precise control of specific CO₂ concentrations, which greatly benefit certain apple cultivars.

The most recent advancement for long-term storage of apples is the use of SmartFresh (1-MCP) technology. Successful application requires an air-tight environment and therefore, the easiest method of application is simply within a sealed CA room. However, there are other methods for treating smaller loads. SCS supplies a Corner Room, which looks like a two-sided heavy-duty plastic tent, with a zipper for easy access. Any size can be manufactured for any room, but the ceiling and other two room walls must be air-tight. A Splitter Room is another option, where one side (or half of the room) can be treated with SmartFresh while the other side is being loaded or unloaded. This provides the benefit of reducing the time between harvest and treatment, which ultimately affects the efficacy of SmartFresh. Again however, the ceiling and other room walls must be air-tight. Similarly, a Divider Room can consist of a single curtain that divides the end of a CA room to create a separate treatment area or a stand alone five-sided zipper tent within the room. These can be made any size for any need.

The SCS SmartChamber is considered the Cadillac treatment room, in that it moves up and down to eliminate treatment of void space and moves side to side for treating different loads very rapidly. This can also be made for any size treatment area and it has inner batons to maintain its shape. The reinforced vinyl material reduces the chance of tearing. An additional advantage of the SmartChamber is that it does not rely on any framework or air tightness of the storage room, as do the other treatment methods mentioned previously.

For more information on any of the above products and technology, please contact Jim Schaefer at:
1-800-487-7994 or e-mail Jim@storagecontrol.com