SUMMARYThe pigments in the peel of Tommy Atkins mango were analysed at six stages during ripening at 22 oC. The loss of green colour and the development of yellow colouration was associated with an almost complete loss of chlorophyll and an increase in carotenoids. Anthocyanin content showed a slight decrease during ripening. An ultrastructural study showed plastids in green fruit with a well developed grana network system. On ripening the chloroplasts underwent extensive disorganisation which was associated with the development of large osmiophilic globules.

The effects of temperature on the ripening of Tommy Atkins mango were studied. Ripening temperature can affect fruit colour, flavour and texture development differently. Fruits at 12°C did not ripen to full eating quality during the 16 days of the experiment. Sugar levels were comparable with those at other temperatures, but acid levels were higher; they retained some green coloration, had lower pulp carotenoids and showed incomplete softening. After 15 days at 17"C, fruits had softened and degreened to an acceptable level but had a poor pulp colour. They were comparatively high in sugars but were also high in acids, resulting in a low sugar:acid ratio. Fruits kept at 22, 27 and 32°C all showed the development of good quality characteristics of high chlorophyll breakdown, high pulp carotenoids, a good texture and a balanced sugar: acid ratio. Similar characteristics were shown at 37"C, although the peel generally appeared mottled and the pulp had slightly lower sugar: acid ratios.

No abstract

Mangoes (var. Tommy Atkins) were exposed to ethylene and acetylene over a range of concentrations at high humidity for 24 h at 25 "C, then ripened in air alone. Ripeness was assessed after 4 and 8 days by analysis of texture, colour development, soluble solids and acid contents.Ethylene in air at concentrations of 0.01 ml litre-] and above or acetylene at 1.0 ml litre-' were found to initiate ripening. Treatment with 0.01 ml litre-' acetylene resulted in limited softening but had no effect on the other ripening changes analysed. Individual ripening processes responded differently to treatment: texture changes were most rapidly affected, while the rate of acidity losses was often reduced in ethylene treated fruits. Acetylene-treated fruits at concentrations of 0.01 and 0.1 ml litre-' showed delayed ripening when compared to those treated with either 1-Om1 litre-' acetylene or ethylene. Increased acetylene concentrations of 2.0 ml litre-' gave a similar response to 1.0 ml litre-', although in some instances there were indications of inhibitory effects. 0 1987 Association of Applied Biologists

No abstract