Determination of film requirements and respiratory behaviour of fresh produce in modified atmosphere packaging
G. B. Y. Christie, J. I. Macdiarmid, K. Schliephake and R. B. Tomkins
Postharvest Biology and Technology Vol: 6 Issue: 1-2 Pages: 41-54
1995
บทคัดย่อ
A simple technique was developed for determining the respiration rate of
produce stored in modified atmosphere packaging (MAP) over the entire storage
period including the initial time when the produce responds to the modified
atmosphere. It is based on a material balance equation that relates the package
film permeability and produce metabolism to the in-package gas concentrations.
The equation is particularly useful for determining basic metabolic processes
of produce such as respiration and ethylene biosynthesis in actual modified
atmosphere packages, even when steady state conditions do not exist.
Alternatively, when the respiration rate is known, the film permeability
required for MAP can be determined. The work reported here shows there is
significant difference between permeability values measured by the ASTM Dow
cell method and the mixed gas cell method. It was found that the film
permeability must be measured by a mixed gas cell method for the technique to
give realistic predictions. When film permeability is determined using this
method at the conditions under which the produce is to be stored, it can be
used directly in the equation without any need for corrections. The material
balance and permeability measurement were tested by determining the metabolic
activity of broccoli (cv. `Marathon') stored under MAP (6% CO2, 1.5%
O2) at 1.5°C. The steady state oxygen consumption, carbon
dioxide production and ethylene biosynthesis were 8.8 ml kg-1 h-1,
9.0 ml kg-1 h-1 and 0.04 
l
kg-1 h-1, respectively. These measurements agree with
published and measured values.