Simulated commercial export of mangoes using controlled atmosphere container technology.
Peacock B. C.
Author Affiliation: Sandy Trout Food Preservation Laboratory, Queensland Department of Primary Industries, Hamilton, Queensland 4007, Australia.
ACIAR Proceedings Series : 40-44
Abstract : Laboratory studies in Queensland and Thailand have shown that CA-stored mangoes have a longer storage life than those held in cool storage alone. Fruits were harvested from 3 commercial sites in Queensland when the content of total solids was judged to be 13-15%. They were de-stalked (in 2 of the 3 sources) and washed, dipped for 5 min. in a hot Benlate [benomyl] solution (500 p.p.m. at 52°C), cooled and sprayed with prochloraz (200 p.p.m.), dried and sorted, and finally size-graded and packed in waxed fibreboard cartons. Some cartons contained polypropylene inserts which cupped the fruits; other fruits were packed on an absorbent pad, but the majority were packed on expanded polystyrene netting. After packing, fruits were transported by road to a precooling room overnight (11°). Pulp temperatures were 18-19° the following morning; after 36 h of transport to Brisbane and overnight holding in a conventional cool room the fruits were placed in a CA shipping container. At loading, the pulp temperature was 12°. Fruits were stored in 5% O2 and 1% CO2 at 13° for 18 days, then evaluated for quality (external colour on a 1-6 scale and severity of anthracnose [Glomerella cingulata] and spot diseases [unspecified] on a 1-4 scale). Fruits were examined for the extent to which sap flow had continued after packaging and for the intensity of visible sapburn on the surface. The findings are tabulated for each of the 3 commercial fruit sources. They showed that ripening was significantly delayed in CA (although there were problems with CO2 control, related to the efficiency of the scrubbing system). There was virtually no anthracnose infection, confirming the effectiveness of prochloraz in its control. However, very high levels of stem end rot were observed, with significant differences in incidence between the 3 commercial sources; the reason is as yet unknown. Fruit colour on removal from storage was not correlated with fruit size, nor was stem end rot development. On removal from the CA container, fruits immediately began to ooze sap and the loss continued for at least 24 h; the sap tended to cause the absorbent pads and polystyrene netting to stick to the fruits. Sap flow was less marked in one of the 3 commercial batches, possibly because the fruits were less mature than those in the other 2 batches. Sapburn development was significantly greater in the fruits which, in one of the 3 batches, had been harvested without stalks. The level of sapburn injury was low but sufficient to influence salability.