Proc. of Second World Avocado Congress 1992 p. 495

The Relationship of Flesh Softening to the Respiratory Climacteric, Ethylene Production and Ammonia Accumulation

M.L. Arpaia and C.J. Lovatt

Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA

 

F.G. Mitchell and G. Mayer

Department of Pomology, University of California, Davis, CA 95616, USA

Abstract. In preparation for future studies to evaluate the relationship between the development of chilling injury and ammonia (NH₃-NH₄⁺ accumulation, we examined the relationship between flesh firmness (mesocarp tissue), respiration (CO₂), ethylene production (C₂H₄) and NH₃-NH₄⁺ concentration during normal ripening at 20C.

The changes in CO₂ and C₂H₄ content in two avocado cultivars, ‘Fuerte’ and ‘Hass’ relative to softening were comparable. The increase in CO₂ and C₂H₄occurred gradually during the course of softening. The respiratory climacteric and the peak of ethylene production did not occur until the fruit were fully ripe (eating ripeness). There was no clear relationship between NH₃-NH₄⁺ levels and changes in flesh firmness although there was an apparent increase in NH₃-NH₄⁺ which roughly paralleled the rise in C₂H₄ and CO₂ production.