ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

Determination of O2 and CO2 permeance, internal respiration and fermentation for a batch of pears (cv. Conference)

R. E. Schouten , R. H. Veltman, H. P. J. De Wild, T. J. Koopen, M. G. Staal and L. M. M. Tijskensa

Postharvest Biology and Technology Volume 32, Issue 3 , June 2004, Pages 289-298

2004

บทคัดย่อ

By combining an existing gas exchange model with the diffusion of respiratory gases over the barrier of thefruitskin, a new gas exchange model was developed. Parameters describing O₂ and CO₂ permeance, internalrespirationand fermentation for a batch of pears (Pyrus communis L. cv. Conference) were estimated using this new gas exchange model. The model was calibrated using data o­n gas exchange, internal and external gas composition and the surface of individual pears. The surface area was calculated using a computer imaging method. The absence of internal O₂ gradients in the aqueous phase of a pear, a prerequisite for using a three-compartment model set up based o­n Fick’s first law, was confirmed using an O₂-electrode probe. Data analysis using the combined gas exchange model resulted in estimated parameters indicating an increased internal affinity for O₂ and increased internal fermentative CO₂ production compared to data analysis using a traditional gas exchange model, based o­n external gas composition. The O₂ and CO₂ permeances were also derived using Ne efflux data. The estimated permeances using the combined gas exchange model were lower than those found with the Ne method. The lower permeances can be explained assuming that the Ne method o­nly assesses the skin permeance, while the permeances for O₂ and CO₂ from the combined gas exchange model represent all the barriers between mitochondria, whererespirationactually occurs, and the external atmosphere. The lower CO₂ permeance found using the new model might also be explained by the relatively high pH of the cytosol.