Tissue permeance of prickly pear cactus stems (Opuntia spp.) To CO2, O2 and H2O vapor as a function of temperature and relative humidity
E.M. Yahia and J.C. Guevara
ISHS Acta Horticulturae 857:461-468. 2010.
2010
บทคัดย่อ
Characterization of the internal atmosphere composition offers the potential to explain variability in response of horticultural products to modified atmospheres (MA) treatments and to quantify permeance of skin to respiratory gases. Stem skin permeance to O2 (bO2) and CO2 (bCO2) were determined as a function of temperature (T) and relative humidity (RH). Surface chambers close to equilibrium with the stem’s internal atmosphere were used to monitor internal atmosphere composition of prickly pear cactus steam. Physical equilibration of chamber contents over fruit surface was completed approximately in 4 h. However, physiological changes in the composition of internal atmosphere indicate that substantial changes continued to develop for extended periods. bO2 decreased in greater proportion than bCO2 at high RH, as a result an inversely proportional relation between permeance to gases and the RH was determined. bH2O also decreased as RH increased. The Arrhenius model describes the T effect on tissue permeance. The following function describes the effect of T and RH on tissue permeance bx=(P0·RHP1+P2)·e(1/T). Surface chambers adhered over stem surface are adequate to quantify the composition of the atmosphere in direct contact with the stem cells.