Dynamic Controlled Atmosphere (DCA) Storage of Fruits and Vegetables

Abstract

The use of dynamic controlled atmosphere (DCA) has been a postharvest concept since the 1980s. Several DCA approaches are discussed. DCA is based on using one of the following techniques to store a fruit or vegetable at an O2 concentration as low as possible to the anaerobic compensation point (ACP) (a.k.a the lower O2 limit (LOL)): measurement of ethanol, measurement of the respiratory quotient (RQ) or measurement of the chlorophyll fluorescence. By the 1990s commercial adoption of the ethanol and RQ methods of DCA was being promoted with limited success. Whilst these two methods are still available today, commercial DCA adoption increased significantly when the chlorophyll fluorescence method (DCA-CF) was introduced at the ISHS CA symposium in 2001 in Rotterdam, the Netherlands. It was first commercially adopted in the 2003–4 storage season in Washington State, USA and South Tyrol, Italy. Although there are many potential post-harvest applications for chlorophyll fluorescence that will be reviewed, research and commercial adoption has focussed primarily on its use in optimising the O2 concentration in storage of fruits and vegetables. This is achieved through a novel method of detection of a sudden change in fluorescence at the lower O2 limit (LOL or ACP). The reasons for its adoption are: Durable and stable (no calibration or parts replacement), real-time monitoring and control of product, pesticide-free technique, accurate determination of LOL, control of storage disorders, especially superficial scald in susceptible apple and pear cultivars without use of pesticides such as diphenylamine (DPA), improved retention of quality, energy savings and possible flavour enhancement and detection of senescence, decay or incorrect storage conditions, i.e. temperature. The current use of DCA methods and future trends will be discussed.