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Vapour heat treatment of Hass and Fuerte avocado (Persea americana Mill.) fruit for extending storage life

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dc.contributor.author Weller PL en
dc.date.accessioned 2016-09-22T10:16:14Z
dc.date.available 2016-09-22T10:16:14Z
dc.date.submitted 1998 en
dc.identifier.uri http://hdl.handle.net/20.500.11892/81973
dc.description.abstract In an attempt to extend storage life of 'Hass' and 'Fuerte' avocado ("Persea americana" Mill.) fruit postharvest vapour heat treatments were used. Vapour heat treatment temperature regimes were 36, 38, 40 and 42 Celsius for 1, 2, 4 or 8 hours. After vapour heat treatment, fruit were cold stored at 3.5 Celsius, for 5 or 6 weeks each. On removal from cold storage fruit were evaluated for firmness, and ripened at room temperature. Once ripe fruit were evaluated for heat/cold damage, days to ripening, weight loss and physiological disorders. These experiments were conducted during the 1996 and 1997 'Fuerte' and 'Hass' avocado seasons. Electron microscope analysis of vapour heat treated fruit revealed heat damage to the epidermis and fruit organelles of certain treatments. The effect of vapour heat treatment on protein synthesis on 'Fuerte' and 'Hass' avocado was investigated using gel electrophoresis, to determine if presumed heat shock proteins were synthesized under the treatment conditions. The activity of pectin methyl esterase was also investigated on the heat treated Fuerte and 'Hass' avocados, to investigate if heat alters the activity of this enzyme. All experiments showed that vapour heat treatment extended 'Fuerte' and 'Hass' avocado storage and shelf life. Evaluation of the time/temperature combination for vapour heat treatment for each cultivar indicated that extension of shelf life was, in some cases, limited by rind heat damage. For the 1996 season, the best time/temperature combination for Fuerte' was at 38 Celsius between 4 to 8 hours, 40 Celsius between 4 to 8 hours and 42 Celsius between 2 to 4 hours. For Hass', best results were achieved at 38 Celsius between 4 to 8 hours. For the 1997 season, Fuerte's best time/temperature combination was at 36 Celsius for 8 hours, 42 Celsius between 1 to 2 hours and marginal results at 38 Celsius between 4 to 8 hours. For 'Hass' the best time/temperature combination were achieved at 38 Celsius and 40 Celsius for 8 hours. Analysis of fruit flesh protein indicated changes associated with vapour heat treatment, and even induction of new proteins, perhaps heat shock proteins, giving 'Fuerte' and 'Hass' avocados beneficial characteristics such as an extension of shelf life. There was a decline in activity of pectin methyl esterase after vapour heat treatment, which was associated with a longer shelf life. en
dc.language English en
dc.subject Plant production en
dc.subject Agriculture en
dc.title Vapour heat treatment of Hass and Fuerte avocado (Persea americana Mill.) fruit for extending storage life en
dc.type Masters degree en
dc.description.degree MScAgric en


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