Reducing postharvest losses

Postharvest losses in citrus can be important. The main causes for such losses are:

Immaturity and overmaturity at harvest
Mechanical damage during harvest, transport and during distribution
Water loss (wilting) due to poor handling
Decay due to blue and green mould and insect damage mainly due to the Mediterranean fruit fly

a. Timely harvesting

Citrus fruit do not continue to ripen after harvest. Therefore, they should be picked at optimum maturity. Immature or overmature fruit tends to be of inferior quality. Maturity indices most commonly used by farmers are fruit colour and size.

Harvesting of citrus for the fresh market is done by hand. Normally, fruit are cut with hand clippers and collected in picking bags and then transferred to field containers and then transported to packing houses or collection centres or transferred directly to the market. However, some sorting is usually done during picking to eliminate defective fruit.

b. Proper postharvest handling

Care should be taken to handle the fruit carefully to reduce physical damage. Grading based on quality parameters such as size, colour, and defects is important to satisfy quality requirements of traders. The fruit is washed with a mild detergent and water in order to remove dirt, insects and loosely adhering mould. They should be left to drip dry in a cool area. Fruits are then packed by hand in containers like sacks or wooden boxes for which common types of containers are used.

c. Proper storage

Citrus fruits are moderately perishable with a shelf life ranging between 2 and 20 weeks depending on the type of fruit. Lemons have the longest shelf life, if picked green and stored at the recommended temperature. Citrus fruit can be cold stored at 0 to 4 °C with very little loss of fruit quality. But fruits vary in their relative susceptibility to chilling injury. Grapefruits and lemons are much more susceptible to chilling injury than oranges and mandarins.

Blue mould and green mould are the most important postharvest diseases of citrus fruits in all production areas. Control measures should include minimizing physical damage, the use of recommended storage temperature and relative humidity, and the use of hot water treatment of the harvested fruit. However, application of fungicides is not allowed in organic farming. Since cold storage facilities in most countries are limited, long-term storage is not normally practiced.

Discussion on postharvest handling of citrus

Inquire among the farmers, how they commonly handle fruit at and after harvest. How do they estimate handling and postharvest losses? Do they see any shortcomings? Are there any ideas for improvement? Together, develop guidelines for proper handling at and after harvest.