Grape Cooling and Storage

he optimum storage temperature for table grapes is −1 to 0 °C at 90–95% relative humidity. Thanks to their high sugar content the berries do not freeze at this temperature; the stem freezes at around −2 °C, which is why the temperature is taken no lower.

The main enemy in storage is grey mould (Botrytis cinerea). The fungus develops even at −0.5 °C and spreads from berry to berry. The industry’s answer is a sulphur dioxide pad placed inside the box; controlled atmosphere brings little benefit for grapes and is not widely used. At Hatipoğlu Tarım, boxes are fitted with a moisture pad once the fruit comes out of precooling.

The second problem is shatter, the loss of berries from the stem. It increases the longer the bunch stays on the vine and is more common in seedless varieties. Not overfilling the box, bagging the bunches and gentle handling all reduce it.