Chlorophyll fluorescence as a predictive method for detection of browning disorders in 'Conference' pears and 'Jonagold' apples during controlled atmosphere storage

Abstract

The chlorophyll fluorescence technique was evaluated as a possible predictive and nondestructive method to detect low-O2 and/or high-CO2 injuries in 'Conference' pears and 'Jonagold' apples stored in controlled atmosphere (CA). The fruits were kept at 0°C in air, 1% CO2 + 2% O2 or 3% CO2 + 1% O2 during five months. Fluorescence parameters of minimal fluorescence (Fo), maximal fluorescence (Fm), and potential quantum yield - (Fm-Fo):Fm, also denoted as Fv:Fm- as well as the incidence of browning disorders were evaluated at several times during storage. No incidence of browning disorders was observed in 'Jonagold' apples, however, they showed a decrease in Fv:Fm during storage time with no differences between the CA-conditions. Air-stored apples showed a higher decrease in Fv:Fm. On the other hand, 'Conference' pears kept in 3% CO2 + 1% O2 developed a lot of browning injuries such as core flush, flesh browning and cavities. Under this CA-condition, a pronounced decrease in the quotient Fv:Fm was observed already in the first 15 days of storage prior to the development of browning, and this behaviour remained during the whole storage period. The air-stored pears showed a similar behaviour as of the air-stored apples with a pronounced decrease in the Fv:Fm at the end of the storage period. The present results indicate that chlorophyll fluorescence is a promising technique to detect browning injuries in 'Conference' pears prior to their development.

Chlorophyll a Fluorescence: A Fast and Low-Cost Tool to Detect Superficial Scald in 'Rocha' Pear (Pyrus Communis L. 'Rocha')?

“…Chl a fluorescence technique is a fast, non-invasive and reliable tool used to assess photosynthesis response to stress in both plants and fruit (Saquet and Streif, 2002;Cavaco et al, 2003). Chl a fluorescence parameters (e.g., Fv/Fm) are reliable and accurate estimators of early changes in the chloroplastic structure/function before any tissue visual damage occurs.…”

“…In contrast a decreasing Fv/Fm has already been used successfully to predict the internal browning in 'Conference' pear, before it is expressed (Saquet and Streif, 2002). As far as we know, Chl a fluorescence has already been evaluated to provide ripening indicators for 'Rocha' pear with a reasonable success (Elias et al, 2004 a,b;Ramalho et al, 2007).…”