Quality of melon is defined by several quality attributes. The most important are appearance, colour, texture and flavour. Appearance and colour are examples of quality attributes judged on the outside, whereas texture and flavour are internal quality parameters. The quality attributes are influenced by variety, pre-harvest factors, harvest practices and post-harvest handling. Determination of fruit quality provides an important indication of the remaining storage potential and shelf-life.
Optimal quality of melon
The most important quality characteristics of melons depend on the variety, the season and the growing conditions. The basis for good melon quality lies in the right harvest maturity. The ripeness of the melons at harvest must be such that they can reach the final consumer with satisfactory ripeness. In the meantime, diseases and disorders should be prevented as much as possible. For all varieties, the minimum requirements for good quality are: intact, healthy, clean, fresh in appearance, firm, practically free of pests, free from damage caused by pests affecting the flesh and free from foreign smell and/or taste.
Quality aspects of melon
Melon external and internal appearance. Photo by Holiday.Photo.Top/Shutterstock.com
General appearanceEach melon variety has his own characteristics such as fruit size, fruit shape, skin structure and colour. In all cases, the consumer will demand fresh-looking and attractive melons. The fruit should not have serious scars or excessive scuffing or other surface defects. The stem-end should be smooth and the fruit should look firm with no signs of bruising.
Piece of melon, partly consumed. Photo by WUR.
FlavourImportant characteristics for the melon flavour are firmness, aroma and sweetness. The sugar content can be well estimated by measuring the soluble solids content (SSC, °Brix) of the flesh. The quality standard for melon requires a minimum of 8 °Brix (equivalent to 8% sugar) or even a minimum of 10 °Brix for certain types of melons (such as Charentais). Less ripe and cold melons have little aroma.
Watermelon skin. Photo by WUR.
Skin colourMelons can have different skin colours. It will be influenced by variety, as well as by ripeness stage and growing conditions. Melons must have sufficient colour development to be acceptable to the final consumer. It depends on the variety. Honeydew melons, for example, show a skin that turns from pale green to cream-colored. A gray or dull colour can be a symptom of unfavourable conditions in the previous chain or a sign of overripeness.
Flesh color and texture are important quality attributes. Photo by WUR
Flesh texture and colourFlesh firmness, melting and juiciness all contribute to the consumer's final judgement. Loss of firmness is one of the most obvious texture changes during ripening. The flesh softening starts from the fruit centre and progresses outwards. A precise firmness test of the flesh can be done with a fruit penetrometer. The flesh colour can vary greatly between melon varieties. The colour can indicate quality issues. For example, browning is undesirable and may indicate overripeness or be the result of unfavourable storage conditions such as stored too cold.
Melon showing a disorder which is visible from the outside. Photo by WUR.
Disorders and diseasesA good quality melon should have no or only minor defects and is in any case free of diseases. Bruises or skin injuries reduce appearance and also provide access routes for pathogens that lead to decay. Disorders are not always visible from the outside. Cutting the fruit may reveal internal discoloration or flesh breakdown, which may be due to overripening. Disorders and diseases can lead to significant post-harvest losses, depending on the season.