Aspects of the Biology and Physics Underlying Modified Atmosphere Packaging

Abstract

In this chapter, we consider the effects of low levels of O2 and high levels of CO2 on the longevity of detached plant tissues; the effects of slicing on tissue metabolism; the determination of gas diffusivities through plant tissues, e.g., the diffusion of CO2 in apples and potato tubers; the measurement of gases in intercellular spaces; experimental modeling for appropriate gas environments in modified atmosphere packaging (MAP), taking into account the rate of respiration; and both steady-state and dynamic modeling for MAP. The most important aspect of MAP for the longevity of these commodities is the decrease in O2 concentration that leads to the induction of a metabolic depression. In the case of climacteric fruit, the metabolic depression is saturable with respect to O2 concentration. For instance, in apple fruits, the delay in the onset of the ethylene climacteric is initiated when the O2 concentration drops below 8%. Also a combination of low temperature (1–2.5 °C) and low O2 concentration (1.5–2.5%) can extend the storage life of apples for a year.