How to Select and Store Watermelons

How to select Watermelons

The absolute best way of choosing a good and tasty watermelon is to have a look at the flesh: it should be deep in color (the deeper the more nutritious the melon will be), absent from white streaks, and with deep-colored seeds.

However, most of the time the fruit is bought whole, so we can't really check the flesh: in this case you should choose a watermelon that's pretty heavy for its size, with a rind that's neither too shiny, nor too opaque.

The best watermelons are those ripened naturally (while still attached to the plant): in this case they will have one yellow/creamy spot, called the "underbelly", which is the place where the plant was resting on the ground. The underbelly is a good sign, since it means the plant has ripened naturally, on the plant.

Absence of an underbelly usually means the melon has been picked prematurely and ripened artificially, which usually results in watermelons with a milder taste and less nutritious flesh.

How to Ripen and Store Watermelons

Despite being 92% water, watermelons contain several important antioxidants, such as beta-carotene and lycopene. Recent studies from the USDA indicate that lycopene and beta-carotene levels increase as the fruit is stored at room temperature.

A glass of purified lycopene: watermelons are a good source of this powerful antioxidant

In addition, recent studies on lycopene itself have shown it has a powerful antioxidant capacity, and it reduces the risk of developing prostate cancer, as well as relieving inflammation symptoms. A 180 gram (6.3 ounce) serving of watermelon provides between 8 and 20 mg of lycopene (more lycopene belonging to fruits with a deeper red flesh), making watermelons a good source of this phytonutrient.

According to this study from the USDA, carotenoid levels were measured in watermelons of three varieties (open-pollinated, hybrid and seedless) stored at 41°F(5°C), 55.4°F(13°C), and 69.8°F(21°C) for 14 days.

The highest increase in carotenoid levels was observed in those stored at 69.8°F(21°C), gaining between 10-40% in lycopene, and 50-138% in beta-carotene. Fruits stored at 41°F(5°C) and 55.4°F(13°C) only gained a small single-digit percentage.

Quoting the researchers The increased lycopene and beta-carotene contents of fruit held at 69.8 degrees Fahrenheit, but not at 55.4 or 41 degrees, indicate temperature sensitivity and enhancement of carotenoid pathway enzymes in watermelon.

The effect can be explained since lycopene content depends directly on the temperature-sensitive, increased conversion of GGPP to phytoene by the enzyme phytoene synthase. Phytoene is turned into lycopene by the enzyme phytoene desaturase.

The best way to store cut watermelons, though, is in your refrigerator, wrapped in plastic. This is a good way to preserve their taste and fragrance without absorbing odors from other foods.