The Science Behind the Tests

Phase I
The commodity tests are conducted in a modestly sized and simplistically designed simulator, constructed by Brecht and Riad. Utilizing different sizes of glass jars and metal chambers that hold various amounts of the commodity being tested, container-shipping environments are created. "We are simply simulating the actual environment within a typical 40-foot container, making the weight and volume of the commodity proportional to actual weight and volume numbers," said Brecht. "This ensures that the rate of change of the CO2 and O2 are directly comparable to what will happen in a container. The amount of commodity in the chamber determines the 'void volume,' which in turn determines the rate of change of the gas concentrations. We monitor the gas levels within each chamber through special ports by inserting a syringe, taking samples of the atmosphere, and measuring them with gas analysis instruments in our lab. The lab chambers are kept sealed until a desired O2 or CO2 level has been reached. This is the same as with an AFAM+-equipped container, in which the fresh air exchange is kept closed until a selected O2 or CO2 set point is reached."

Phase II
When the desired set point is reached, the second part of the testing begins. "Once our test chambers reach the ideal atmosphere levels, we insert various sizes of copper tubing to simulate the fresh air exchange component of AFAM+. The more narrow and long the tube, the less air that moves into the chamber. The shorter and wider the tube, the more air that moves into the chamber. We utilize a computer program developed by Khe Chau, professor of agricultural and biological engineering at the University of Florida, which calculates the amount of fresh air needed simply by entering the respiration rate and weight of the given commodity. This is how we determine the correct rate of fresh air diffusion to keep CO2 and O2 at optimum levels. These gas levels are typically maintained long enough to represent the average shipping container voyage."

Phase III
The final phase of testing involves studying the quality of the commodity after its simulated shipment and comparing it to the same commodity held in a control treatment that simulates traditional fresh air exchange systems. Is the color ideal? Has decay set in? Has it lost moisture? Does it appear to be a commodity that would benefit from AFAM+ technology? Is product shelf life prolonged?