THE EFFECTS OF HOT-WATER TREATMENTS IN COMBINATION WITH COOLING AND OR STORAGE ON THE PHYSIOLOGY AND DISEASE OF MANGO FRUITS (MANGIFERA-INDICA LINN.)/

This paper reports three separate studies. The first involved devising an effective phased hot-water disinfestation treatment on the basis o f reported lethal time (LT90) values of 5-15 min at 46 degrees C core temperature and heat units. Phased hot-water treatment at 36.5 degrees C for 60 min plus 46.5 degrees C for 43 min (4185 degree minutes) att ained and maintained a seed (core) temperature of 46-46.5 degrees C fo r 5-12 min. The impact of phased hot water was tested against the reco mmended treatment (46.5 degrees C for 90 min - 4184 degree minutes) an d a control, on the basis of fruit colour, taste, flavour firmness and the incidence and severity of diseases, internal and external injury and physiological disorders. Following hot-water treatments,'Keitt' an d 'Tommy Atkins' mangoes were subjected to an array of treatments incl uding air or hydrocooling, 10 d of storage at 13 degrees C with or wit hout 1 d of intermittent warming at 34 degrees C (sixth day) and 2 d r ipening at 22 degrees C respectively as a simulation of possible handl ing procedures. Phased hot-water treatment and 1 d of intermittent war ming resulted in a significantly low incidence and severity of interna l and external injury and diseases and low off-flavours compared with control and hot water at 46.5 degrees C for 90 min. The impact of the above hot-water treatment at half heat units previously tested (2092.5 degree minutes) in combination with intermittent warming (34 degrees C) during 12 d of cool storage (13 degrees C) showed that treatment wi th hot water at 46.5 degrees C for 45 min and 2 d of intermittent warm ing resulted in a significantly low incidence and severity of external injury and diseases, softer fruits, higher degrees Brix and better ge neral appearance. The incidence of disease was influenced by preharves t factors and the effects of hot-water treatments on fruit quality was dependent on time/temperature combinations and not on total heat unit s received. Intermittent warming advanced fruit ripening.