Fruit constantly emits ethylene inside the chambers. To efficiently reduce the concentration of ethylene in these spaces, it needs to be eliminated at a speed that is faster than the production ratio of the fruit. This is achieved when the airflow that passes through the machines in one hour is equal to the volume of the chamber.
Depending on the chamber's volume, Bioconservacion recommends installing the appropriate type and number of machines needed to filter the full volume of the chamber in one hour. Bioconservacion has a range of Ethylclean machines to adapt to the various sizes and types of chambers. The Eth-V1700 machine can filter 1700 m3 of air/h.
There are other machines on the market that are designed to eliminate etyhlene and purify the air, based on other filtration technologies, such as photocatalytic oxidation or forced air through ozone. However, the flow rates of these machines are far inferior to those of the Ethylclean range. The strongest equipment that we have come across on the market (BioTurbo 6000, Miatech) can only filter 250 m3/h (around 7 times less than the Eth-V1700).
Bioconservacion, based on current literature ( ), has developed a programme to simulate ethylene elimination in chambers according to airflow per hour. If we imagine a chamber with the following characteristics, we can simulate the evolution of ethylene concentration using both pieces of equipment.
- Volume = 1400 m3
- Fruit Weight = 250 t
- Average emission of fruit = 0.5 and 1.5 µl/Kg*h
- Concentration of ethylene at the beginning = 2 ppm
- Possible ethylene leakages are not taken into consideration
- It is considered that both technologies are appropriate for and capable of oxidising ethylene at an efficiency of 90%
The charts (see Figure 1) clearly reflect the importance of the filtration airflow in the efficiency of ethylene elimination. In this particular case, over a 4-hour period, the ETH-V1700 machine reduces the initial concentration of 2 ppm of ethylene to levels of lower than 0.2 (0.5 µl/Kg*h emission) and 0.1 ppm (1.5 µl/Kg*h emission). On the other hand, the Bioturbo 6000 system needs 13 hours to reach a level of 0.6 ppm when the emission is 0.5 µl/Kg*h, and it cannot go any lower than 1.6 ppm when the emission is 1.5 µl/Kg*h. This system is far more sensitive to emissions than the Bioconservacion system, and does not guarantee effective protection against ethylene.
Figure 1. Simulation of ethylene elimination.
Bioconservacion machines need a periodical change of their granulate modules (according to the emissions of stored fruit) and minimum maintenance. Technology based on forced air through Ozone requires more costly maintenance, and also implicates an annual change of consumables.