back to home page
Worldwide transport of fresh fruit and vegetables utilizes a "cold chain" to maintain freshness of produce from farm to consumer. Air cooling systems, however, dry the air in the cold storage room or in the reefer container. The dry air drains water from the produce, reducing quality and shortening shelf life. For many sensitive products, the dry air of the reefer or cold store, for even a few days, makes sea transport impossible.
Adding high humidity without wetness to the air of the ship cold store or reefer can be the solution to transport of perishable products. High humidity, over 90% RH, reduces the water loss of the produce, preserving freshness and extending shelf life. Products like bananas and tomatoes arrive in better condition; products such as green peppers and leafy greens can now be shipped safely by sea for long distances.
High humidity adds a new dimension to transport possibilities. At Optiguide we are shaping the future for transport cooling systems.
The Tabor FogRight Atomizer uses compressed air to produce micro-droplet "dry fog" which evaporates into the air before it reaches the ground. It has a large nozzle opening which prevents clogging, a major problem for pinhole foggers. The OptiSense Humidistat uses fiber-optic technology to accurately and reliably control relative humidity in the 86-98% RH range, a level where other RH meters become saturated. The system provides full data to any connected PC, and settings can be changed from outside the cold room or reefer.
In cold store ships, the water, compressed air, and a communications link are supplied by the ship. Optiguide can supply its system to operate as a self-contained unit for reefer containers on sea and land.
Keeps the cold chain humid: More and more products are being stored with high humidity, at post harvest, in distribution centers, and in supermarkets. The Optiguide system maintains the humid chain in transport, allowing longer transport time and longer shelf life after arrival.
Makes sea transport feasible for sensitive products: Leafy vegetables, capsicum, tomatoes etc., can be shipped by sea for long periods, saving expensive air transport.
Maintains freshness: Cold storage drains water out of the produce. High relative humidity means the surrounding air cannot hold more water vapor, so the water stays in the produce, and does not evaporate into the air. The produce retains its turgor, keeping fresh quality until its destination.
Maintains price: Water loss and less freshness mean lower quality produce- and lower prices. Quality prices after storage with Optiguide's Controlled Humidity Solution pay back installation costs quickly.
Extends shelf life: Produce shipped with high humidity has a longer shelf life at destination.
Remote Control: When the OptiSense Humidistat is connected to a PC, full data and controlcommunication can be maintained at a central shipboard site - or linked to any PC in the world!
Low Maintenance: With its large 1.5 mm orifice, the FogRight nozzle won't clog like pinhole foggers do, and with no moving parts in the fogger, maintenance is minimal.
Research conducted in Japan at Okayama University's Faculty of Agriculture has demonstrated that high humidity, 95% RH, is very effective in maintaining freshness of bananas for weeks before ripening. The charts below show that when the produce is stored in a high humidity environment, weight loss is reduced, flesh firmness is preserved, respiration is reduced and delayed, and ethylene production is delayed. In summary, shelf life is extended and quality improved.
Ship's Cold Stores Optiguide has years of experience adding humidity to cold storage rooms on land, and our Controlled Humidity Solution is already operating aboard cold storage ships, like Agrexco's Carmel Exotic. Initial results have been so successful that Agrexco is installing Optiguide systems in more ships. Freshness is preserved so that all products arrive in better condition, and the new system will allow sea transport for many items which until now had to be shipped by air. The chart below (from Carmel Exotic) shows that RH levels were maintained between 96 and 98% RH (top series, left-hand scale) by controlling the activation time of the Tabor FogRight Atomizer (bottom series, right scale).
Reefers Optiguide is developing its system as a self-contained unit for use in reefer refrigerated containers. In recent tests, the Optiguide system was installed for three weeks in a container holding cartons of mangos. While a comparison system was not able to provide stable humidity over 85%, and still caused moldy boxes and a wet floor, the Optiguide system provided controlled 95-96% RH. The cartons remained dry and the fruit remained fresh.