Flavor Investigator: Watermelon

Watermelon can easily be called the “iconic fruit of summer” with its bright pink rind, striped green exterior and dark seeds speckled throughout it just screams summer. The flavour of this summer time fruit is fresh, green and fruity with cucumber notes.  Watermelon (Citrullus lanatus var. lanatus )  comes from the flowering plant family Cucurbitaceae and is native to Africa.  It has been cultivated as far back as 2500 B.C and has even been evidenced in ancient hieroglyphics. Watermelons are about 92% water and for this reason early traveler used them as a source of water on travels-nifty!

The Compounds Responsible for Watermelon Flavour

The topic of watermelon flavour has changed over the years. This is not surprising considering new technologies and study methods are being created continuously. In the past it was believed that the primary odorants for watermelon were the C₆ and C₉ alcohol (Z,Z)-3,6-nonadien-1-ol. These watermelon alcohols are described as having an odour of sweet, green, cucumber, melon and waxy.  All of these odours can be thought of as ‘watermelon rind-like.’

The reason these alcohols were thought to be primarily responsible for watermelon’s aroma is due to how the study was conducted. During testing an enzymatic reaction occurred, turning the aldehydes into alcohols.  Today, it is believed (Z,Z)-3,6-nonadienal is considered to be the main contributor of watermelon flavour. However other watermelon aldehydes also contribute to this flavour too. For example, the ‘leaf aldehyde’ cis-3-Hexenal is also found in watermelon and has an intense grassy-green odour.

The Compound Responsible for Watermelons Pink Colour

Let’s take a minute to shift our attention away from the flavour of watermelons to the colour of them.  Watermelons have a beautiful pink flesh that is highlighted by the stripped green outer rind. There are other varieties of watermelon that display different colours but right now I want to focus on the pink colouration.  The compound responsible for this characteristic colour is lycopene, a carotenoid pigment.  Lycopene is a red pigment found in fruits such as tomatoes, rosehips and pink grapefruit. It is the most common carotenoid (organic pigment) found in the human body and is even linked to many health benefits. Despite its pink colour, watermelon actually has more lycopene than tomatoes as it estimated to contain 72 micrograms per gram. In contrast, tomatoes are known to contain about 42 micrograms per gram.

Possible Unique Flavour Combinations for Watermelon

• Watermelon and Chilli- Combining fruit with chilli has become a classic combination and does not fail to please in this case. The slight smokiness of chilli is highlighted by the subtleness of watermelons flavour. The flavour overall is somewhat grassy but candy like as well.
• Watermelon and Rosemary- Rosemary is one of my favourite flavours because of its fresh, eucalyptus notes. The coolness associated rosemary is able to pair with the grassiness of watermelon to create a summer time “green” flavour.
• Watermelon and Cinnamon- Cinnamon is a warm favour that is slightly bitter but overall sweet. Because of this it does not overwhelm the natural sweetness of watermelon. When the two combine it creates an exotic flavour reminiscent of Africa- the native land of watermelons.