Ensuring air quality in museums, historical archives, art exhibitions and in areas with objects of great historical or other significance. Specialized applications in shipping, areas relating to airports, agricultural produce, foodstuffs, etc.
1. Introduction to the problem
Ethylene is produced in most plant tissues and is known to be an important factor for the initiation of the ripening of fruit. The familiar phenomenon of accelerating the maturation of unripe fruit from the presence of overripe fruit in the same enclosure (including refrigerators) can be caused by a tiny emission of ethylene. Thus, ethylene acts as a phytohormone (plant hormone), because it carries the chemical signal of "commence process of ripening." The ripening of the fruit, the opening of flowers and the dropping of leaves are activated and regulated. There are numerous substances acting as phytohormones, but ethylene is the only gaseous phytohormone.
However, the natural production of ethylene from the fruit can cause problems in storage facilities. Ethylene destroys the green color of the plants, so lettuce and other vegetables of a mature green colour available in the market but not at a fully mature stage will be destroyed if stored with fully ripened produce. The production of ethylene is increased when produce is bruised or attacked by fungi that cause decay.
2. Ethylene Control
The range of DIMTECH S.A. equipment regarding the control of ethylene is wide and addresses both large warehouses and on a domestic scale as well as for means of transport (ships, trucks, trains) of fresh agricultural produce. More specifically Dimtech S.A. offers:
- Dry chemical means in the form of granules. This medium consists of a technological innovation as far as the potential for the retention of ethylene, and other gases is concerned. It consists of grains of a diameter of ~ 3 mm from zeolites extruded with potassium permanganate. This medium is used either in bulk in ethylene removal devices or in plastic canisters. The removal capacity of ethylene is from between 2.5% and 3 % by weight.
- Fixed polystyrene canisters into which the chemical medium is placed. The canisters are of code types PP-18 with a capacity of 0,014 m³ and PP-12 with a capacity of 0,028 m³. The canisters have specified dimensions and have guides which allow easy placement in ethylene removal units and minimize the leakage of air.
- Fixed or mobile ethylene removal units (ETHYLCLEAN), which have a fan which circulates the air and chemical filters impregnated with 12% sodium permanganate. The dimensions of these units vary and can meet the demands of large spaces. They are made of stainless steel or galvanized sheet metal with an electrostatically spray painted surface.
- Chemical filters in the form of cylinders which are adapted to the louvers or to the openings on air circulators in storage areas or in transport. These filters contain granules of zeolites extruded with an oxidizing agent in order to remove gaseous pollutants, naturally including ethylene as well. These filters are available in various sizes and contain chemical agents so that they can be combined for the effective retention of ethylene, according to the dimensions and the load in each space.
- Sachets for preserving food which are small in size, suitable for commercial and domestic use. They contain chemical means for the removal of ethylene and can easily be placed between packages of fresh vegetables (bags, boxes, etc). The sachets are made of Tyvek®, they have good mechanical strength, they are resistant and non absorbant to moisture, they are made of environmentally responsible material and may come into direct contact with food without any problem.
- Thermography (temperature recorders), mechanical or electronic function. The temperature recorders are placed in storage areas or even among packaged goods. They record at predetermined intervals the temperature levels. In this way we can have a complete history of storage conditions of the product. The type of mechanical temperature recorder is IN TRANSIT and the types of electronic temperature recorders are LOG TAG and BIO LOG.