Grapefruits must be harvested in full maturity, as it happens with other citruses. Like mandarins, they cannot be stored at very low temperatures since they develop defects in the skin.

Grapefruits must be harvested in full maturity in order to assure the best quality, since this citrus fruit does not ripen in ripening rooms. Citruses do not mature in ripening rooms because they do not have reserved starches. Fruit with sugar must be harvested at the moment when they are ripe.

As explained with lemons and limes, grapefruits cannot be stored at temperatures below 10ºC since they develop deteriorations, spots in the skin. Therefore, grapefruits are usually stored at temperatures between 10-15 ºC and a relative humidity of 90-95%. The high humidity level, as it happens with mandarins, is applied to avoid the loss of water which does not recover once the fruit is harvested.

There are researches on the reaction of grapefruits in controlled atmosphere rooms. Storage at 2% of oxygen reduces the damages by cold if grapefruits are maintained at temperatures below 5ºC. Nevertheless, the use of controlled atmospheres is not wide spread due to its high economic cost.

Grapefruits are very sensible to cold and many times there appear dark spots in the skin. There can also appear other types of skin discolouration along with interior black seeds caused by the action of different fungi.

Grapefruits, like mandarins, are very sensible to low temperatures and prone to injuries by cold.

The external symptoms are discolouration of the skin and increase of susceptibility to aging.

Inside the fruit damaged by cold, the pulp around the seeds turns into a pale colour and the white segments that separate the gores darken until the become brown.

These damages by cold appear with more frequency when the fruit is maintained for more than a month at temperatures near their freezing point, around -3ºC and 5ºC, or at 5ºC for more than a month.

Another type of deterioration that grapefruits undergo is caused by different fungi like Aspergillus or Alternaria, that cause a slight variation in the colour of the skin and turns the seeds into black.