Oxygen in the air can not be completely removed from the atmosphere, due to the presence of oxygen is necessary to keep the course of normal metabolism. Below 1-3% oxygen, many commodities were damaged. Similarly, the concentration of CO2, the tolerance limit commodity to these gases vary. Some commodities are not resistant to high CO2 concentrations. Some commodities hold at 1% concentration of CO2 was another commodity hold at 20% or more.
Table 6. The concentration of O2 and CO2 is considered good for Storage and Transport
Though the concentration of O2 and CO2 optimum is always the chance that ethylene gas accumulation and efforts should be made to absorb (srubbing) with chemicals such as potassium permanganate or with ultraviolet irradiation, or by lowering the air pressure up to 1/10 normal air. There are three ways that are usually used in storage that involves changing atmosphere that is:
a. CA = controlled atmosphere
b. MA = modified atmosphere
c. LPS = low pressure (hypoboric) storage.
The difference between CA and MA storage is the storage system CA, the concentration of carbon dioxide (CO2) and oxygen (O2) is set continuously through a device that is outside the system, while MA storage, the concentration of carbon dioxide and oxygen regulated and determined by the respiration of the product and the degree of permeability of packaging materials or to hermitisan of space and transportation vehicles.
For some commodities, some other types of gas can be added, such as carbon monoxide gas or can be reduced or eliminated, such as ethylene gas. In a system of LPS (Low Pressure Storage) drop in oxygen levels achieved denganmengurangi total pressure of the air surrounding the product.