Changes in cell-wall-degrading enzyme activities in stored olives in relation to respiration and ethylene production: Influence of exogenous ethylene

Abstract

The activity of various enzymes (α-D-galactosidase; β-D-galactosidase; α-L-arabinofuranosidase; α-D-mannosidase, β-D-N-acetylglucosaminidase, cellulase and polygalacturonase) associated with the cell wall during olive storage was assayed in order to establish the behaviour of the enzymes as a function of the ripening stage and in relation to the production of ethylene. The effect of exogenous ethylene (100 mg/l for 24 h) was also evaluated. In addition, gaseous emissions of CO2 and ethylene during olive storage were monitored. The results obtained indicate that the high initial CO2 level in the green olive coincides almost exactly in time with the climacteric maxima when the fruit is on the tree. After the rapid decrease in the respiration rate of green olives during storage, the CO2 production rate increases as the stage of maturity advances. The results also indicate that ethylene is not capable of stimulating the activity or synthesis of enzymes in green olives, but can produce such a stimulation in black olives. Furthermore, during the first day of storage there were very marked decreases in enzyme activities. Small variations in the conditions of aerobiosis in post-harvest ripening were shown to have notable effects on the normal metabolism of the fruits.