To determine the minimum flesh firmness that FEMA fruit can be exported without becoming overripe after storage, and to determine the effect of extended storage of FEMA fruit (stock rolling)

To determine the effect of FEMA fruit packed at 4.0 kg on fruit quality after 4-6 weeks cold storage, and to determine the maximum storage period from harvest at a range of packing firmness’s before fruit quality is compromised.

A FEMA orchard in Vyeboom was harvested first at FEMA release followed by two more harvests, one and two weeks after release respectively. Fruit were subjected to a standard 600 ppb SmartFresh^SM treatment and stored for 5, 8, 12 and 14 weeks at -0.5°C. Evaluations were conducted at the end of cold storage and after a simulated shelf life of 7 days at 20°C.

2014

Fruit harvested from the 1^st (week 12, 5.9 kg) and 2^nd (week 14, 5.7 kg) harvests and stored for 12 weeks did not ripen below 5.0 kg during a 7 day shelf period and so no mealiness developed. Harvest 1 stored for 16 weeks however, ripened to 2.9 kg, but did not express mealiness as fruit had been subjected to sufficient cold storage (>12 weeks).

Fruit harvested in weeks 15 and 16 (Harvest 3, 5.0 kg; Harvest 4, 4.9 kg, respectively) and stored for less than 12 weeks at -0.5°C, generally ripened below 4.0 kg with the resulting expression of mealiness. Fruit stored for 12 weeks resulted in no mealiness in Harvest 3, and only 7.3% in Harvest 4 fruit.

This data suggests that the SmartFresh^SM concentration applied was not effective in maintaining flesh firmness after 16 weeks cold storage in Harvest 1 fruit and in post optimum fruit harvested in weeks 15 and 16.

No astringency was noted during the trial.

2015

Due to seasonal factors fruit firmness did not drop. Subsequently fruit were not harvested at the desired firmness of 4.0 kg. Fruit colour reached the maximum acceptable level of 3.0 according to the standard industry colour charts at Harvest 3, thus not making it worthwhile to harvest more mature fruit. Post shelf life fruit quality was acceptable even after 14 weeks cold storage. SmartFresh^SM effectively prevented ripening resulting in a sweet, crisp fruit with supressed mealiness expression.

No astringency was noted during the trial.

2016

Fruit harvested just before FEMA release protocol (Harvest 1, 6.2 kg), treated with 600 ppb SmartFresh^SM did not express any mealiness after cold storage and a shelf life, even after 16 weeks. Fruit harvested within FEMA standards (Harvest 2, 5.8 kg) expressed low incidence of mealiness after 16 weeks cold storage. In fruit harvested outside the FEMA standards (Harvest 3, 5.2 kg) and treated with 600 ppb SmartFresh^SM, mealiness was already detected after 5 weeks cold storage in low quantities (3.8%). Internal browning and internal breakdown were detected after 8 weeks storage.

No astringency was noted during the trial.

In the 2014 season fruit firmness lower than 5.0 kg at harvest were obtained. It was advised that these fruit should be cold stored for at least 12 weeks to reduce the incidence of mealiness. In the same season, fruit harvested within the FEMA release criteria ripened to 2.9 kg after 16 weeks cold storage and shelf life. In the 2016 season, fruit harvested in the FEMA release criteria of the same storage time, did not ripen lower than 5.1 kg.

Results suggest that a higher concentration of SmartFresh^SM (1000 ppb) could be considered to ensure that fruit do not soften and express mealiness. Further work should possibly focus on a maximum firmness that can be harvested and still result in a good eating quality. Orchards are sometimes compromised with overripe fruit and advanced skin colour, while having acceptable sugar levels above 14%. Long term storage of these orchards which may not have made the FEMA release due to high firmness, can result in the expression of post-storage disorders such as internal browning and mealiness.

Results suggest high risk of orchards harvested with flesh firmness of 4.0 kg.