The effects of hot-water treatments in combination with cooling and/or storage on the physiology and disease of mango fruits (Mangifera indica Linn.).
Nyanjage M. O., Wainwright H., Bishop C. F. H.
Author Affiliation: Writtle College, Chelmsford, Essex CM1 3RR, UK.
Journal of Horticultural Science and Biotechnology 73 : 589-597
Abstract : Three separate studies are reported. The first involved devising an effective phased hot-water disinfestation treatment on the basis of reported lethal time (LT90) values of 5-15 min at 46°C core temperature and heat units. Phased hot-water treatment at 36.5°C for 60 min plus 46.5°C for 43 min (4185 degree minutes) attained and maintained a seed (core) temperature of 46-46.5°C for 5-12 min. The impact of phased hot water was tested against the recommended treatment (46.5°C for 90 min, 4184 degree minutes) and a control, on the basis of fruit colour, flavour, firmness and the incidence and severity of diseases (primarily anthracnose caused by Colletotrichum gloeosporioides [Glomerella cingulata] and stem end rots), internal and external injury and physiological disorders. Following hot-water treatments, Keitt and Tommy Atkins mangoes were subjected to an array of treatments including air or hydrocooling, 10 days of storage at 13°C with or without 1 day of intermittent warming at 34°C (sixth day) and 2 days of ripening at 22°C, respectively, as a simulation of possible handling procedures. Phased hot-water treatment and 1 day of intermittent warming resulted in a significantly low incidence and severity of internal and external injury and diseases and low off-flavours compared with the control and hot water at 46.5°C for 90 min. The impact of the hot-water treatment at 46.5°C for 45 min (half the heat units previously tested, 2092.5 degree minutes) in combination with intermittent warming (34°C) during 12 days of cool storage (13°C) showed that treatment with hot water at 46.5°C for 45 min and 2 days of intermittent warming resulted in a significantly low incidence and severity of external injury and diseases, softer fruits, higher °Brix and better general appearance. The incidence of disease was influenced by preharvest factors and the effects of hot-water treatments on fruit quality was dependent on time/temperature combinations and not on total heat units received. Intermittent warming advanced fruit ripening.