Carbon dioxide is a colourless gas with a slight pungent odour at
very high concentrations. It is an asphyxiant and slightly corrosive
in the presence of moisture. CO2
dissolves readily in water (1.57 g/
kg at 100 kPa, 20
C) to produce carbonic acid (H2
CO3) that
increases the acidity of the solution and reduces the pH. This has
significant implications for MAP of foods. The high solubility of CO2
can result in pack collapse due to the reduction of headspace
volume. In some MAP applications, pack collapse is favoured, for
example in flow wrapped cheese for retail sale.