Dynamic Control of the Oxygen Content During CA Storage of Fruits and Vegetables

Abstract

The lowest possible oxygen content during CA storage of fruits and vegetables is considerably lower than what is applied in practice. Fermentation of the stored crops is avoided in this way. However, due to this safety margin, the maximum yield in product quality is not achieved. Application of the lowest possible oxygen concentration asks for a system in which the oxygen content can be watched dynamically and corrected immediatly when the stored product starts fermenting. This can be realized by making use of changes in the respiration behaviour of crops, monitored e.g. by the start of ethanol production. For the development of a Dynamic Control System (DCS) to obtain the optimal CA storage conditions with respect to produce quality, the tolerance of several crops for mild forms of temporarily fermentation was tested. Ethanol accumulation in apples and Brussels sprouts was studied. Both crops were stored in extremely low oxygen contents or in nitrogen. Quality development was measured by: firmness of apples, colour and leaf abscission of Brussels sprouts. A linear increase of the ethanol content was observed. The tolerance of Jonagold apples is very high, since accumulation of more than 100 mg/100 g apple tissue did not influence the firmness of the apples. In Brussels sprouts a decrease of ethylene sensitivity could be observed. The results will be discussed in relation to the development of a Dynamic Control System (DCS) for CA storage of fruits and vegetables.