PHYSIOLOGICAL AND BIOCHEMICAL EFFECTS OF CARBON MONOXIDE ADDED TO CONTROLLED ATMOSPHERES ON FRUITS
Although CO is oxidized to CO2 in plant tissues which, in turn, is incorporated into organic acids and other products, it can have direct effects on physiological responses and biochemical changes in fruits since it mimics C2H4 action. These effects are dependent upon O2 and CO2 levels as well as the temperature and duration of storage. CO + air stimulated CO2 and C2H4 production and enhanced softening of peach fruits. However, CO + elevated CO2 and/or reduced O2 levels decreased respiration and C2H4 production rates and delayed softening. Differences among treatments in soluble solids, total sugars, pH, titratable acidity, total carotenoids, and total phenolics were small. CO slightly reduced flesh browning associated with internal breakdown in peaches held in 5°C.
If CO (5–11%) is to be used on fruits, it should be combined with reduced O2 (2–4%) to maximize its fungistatic effects and minimize its C2H4-mimicking effects on ripening. Commercial use of such treatment will depend upon development of technological procedures that would minimize CO's hazards to humans during postharvest handling of horticultural crops.