Largescale testing of Ready-to-Eat (RTE) protocols for mangoes.

MSc-thesis abstract (submitted 1 July 2014):
Mangoes are very popular exotic fruits on the fresh market industry around the world, but the requirements of the consumer for fresh fruits are high.
To satisfy the consumers, markets and wholesalers came up with a new concept: Ready-to-Eat (RTE) for avocados and mangoes. The RTE concept states that the mango or avocado is ripe and soft, and possible to eat within a couple of days.
But the consumers want more than a ripe, soft, eatable mango; they want mangoes that are soft and sweet at the same time. This led to the development of a new concept: Ready-to-Enjoy (RTJ).

This study examined different storage temperatures and ethylene treatments to ripen mangoes in a semi-commercial way. Furthermore, it was investigated which mangoes at arrival at the wholesaler are suitable for the RTE and which are suitable for the RTJ concept. We assumed that the initial dry matter content of the pulp can be used as indication.
In this study two commercial mango cultivars were used; Mangifera indica L. cv Keitt and Kent.
The mangoes came from different regions and wholesalers, the first batch arrived on the 23th of September 2013 and latest batch on the 10th of December 2013.
The mangoes were stored at three different temperatures (16°, 20° & 24°C), half of each batch received an ethylene treatment and half not. Every day the firmness of the fruits was measured. Additionally, the total sugar content, dry matter content and specific gravity were measured.

The results of the two experiments showed that 20° C was a better storage temperature compared to 16° and 24° C as the fruits were faster at the Ready-to-Eat stage and had a good visual quality.
In both experiments no clear effect of the 1 day ethylene application on the ripening process was found, only at a storage temperature of 16°C some differences were shown.
In the second experiment the differences in ripening behaviour between small and big, hard and soft mangoes were investigated, but did not show any significant differences.
The correlations between dry matter and specific gravity, and dry matter and brix were tested for different batches and for one batch it was tested over time (1, 4, 7 & 10 days after arrival at the storage rooms). The results from this experiment were rather poor and providing little information, only a few results showed a trend between dry matter percentage and brix.

Ethylene has different effects on the ripening process; most of them are not so clearly understood yet. But out of these experiments it seems that ethylene narrows down the variation in ripening time and synchronized the ripening time.
Furthermore, the float-sink experiment showed that mangoes that sink in tap water had a significantly higher dry matter and brix concentration compared to mangoes that float in tap water. Finally the Ready-to-Eat concept, which already exists longer, seems to work quite well. Nevertheless, the protocol still needs to be redefined for each cultivar individually.

Keywords: Mangifera indica L. – postharvest – firmness – Ready-to-Eat – Ready-to-Enjoy