ISHS Acta Horticulturae 600: VIII International Controlled Atmosphere Research Conference
GAS EXCHANGE RATES IN ITALIAN 'CONFERENCE' PEARS WITH DIFFERENT SUSCEPTIBILITY TO BROWN HEART |
| Authors: | P.E. Zerbini, M. Grassi, A. Rizzolo |
| Keywords: | respiration, fermentation, modelling, brown heart |
| Abstract:
Brown Heart (BH) in ‘Conference’ pears (Pyrus communis L.) can appear in CA storage. BH could be due to lower energy production than maintenance energy needs. Gas exchange rates of individual fruit were measured in different pO2 and pCO2 at 0°C at harvest and during the first period of storage, on ‘Conference’ pears of different maturity stored in 2% O2 and 0.7 or 5% CO2. Gas exchange rate data were analysed by non-linear regression using Michaelis-Menten type models. O2 uptake followed a model with no inhibition by CO2. At harvest, maximum O2 uptake decreased with later harvest, and during storage it decreased in early-harvested pears, but not in late-harvested ones. Resistance to gas diffusion was higher for O2 than for CO2, contrary to what is predicted by Graham’s Law. Late-harvested fruit showed higher resistance to gas diffusion, increased KmO2 with storage time and reduced aerobic respiration at pO2 close to that of storage atmosphere. Late-harvested fruit showed higher BH than normal-harvested fruit, especially with high pCO2. Gas exchange rates could be related to BH in late-harvested fruit. No effect of CO2 was found on O2 exchange rates. It appears that processes other than gas exchange rate are involved in the relationship between CO2 and BH. | |
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