How to ripen cut watermelon?
The contents of this article are fact-based except otherwise stated within the article.
Author bio
Dr Anny March PhD is a food Engineer with expertise in Food Technology, Natural Polymers, Edible Films, Enzymes, and Nanotechnology.
Dr Anny Manrich’s Highlights:
- Research and Technology at the Brazilian Agricultural Research Corporation
In this brief guide, we are going to answer ‘how to ripen cut watermelon?’ Also, we will see how to pick the perfectly ripe watermelon and a few ways you can store it.
How to ripen cut watermelons?
It is not possible to ripen cut watermelons. Once harvested, watermelons stop their ripening process. After being cut, watermelon gets exposed to the external environment and will only continue to lose its moisture. Watermelon, as the tomato, contains lycopene, the pigment which gives the red color to these fruits, is in a non-climacteric fruit, unlike tomato. That means, it won’t ripen after being harvested (1).
If you place your cut watermelon in the fridge this moisture loss may be prevented but still, you can’t store watermelons for more than 2 days in the fridge.
How to ripen uncut watermelons?
To ripen an uncut watermelon, it is necessary to apply ethylene to the fruit’s atmospheric environment. Postharvest treatment with ethylene is commercially used to induce ripening of non-climacteric melons and watermelons.
As a source of exogenous ethylene, you can use a ripe banana or another ripe climacteric fruit, such as avocado, mango, guava). Place ripe bananas close to the watermelon for a few days. The maturation process may take some time.
How to tell if the watermelon is ripe on its vine?
To identify a ripe watermelon, you must be aware of some signs that characterize ripe watermelon. Watermelon rind is very thick and hard. The identification of watermelon ripeness from its appearance such as size or skin color is very difficult. The common subjective method is usually based on the sound produced by a slap (2). It should sound hollow. If it’s a dull, muted thudding sound, put it back.
One of the initial signs of fully ripened watermelon is when the curly green shoots near the stem have turned brown and dried out. The bottom of the watermelon, a ‘field spot’ – where it rests on the ground, also turns a light green to a creamy yellow.
The skin of the watermelon also goes to a duller matte appearance from its previous glossy shine. The skin of ripened watermelon also gets rougher and tougher as it gets close to its ripeness. The fruit rind is more elastic, has less firmness, when the fruit is ripe (2).
Why don’t watermelons continue to ripen after harvesting?
Watermelons do not continue to ripen after being harvested, because they are not climacteric fruits. Once harvested they don’t ripen.Climacteric fruits can ripen fully if they are harvested when they are fully grown. On the other hand, non-climacteric fruits can mature fully only when still attached to the plant. After being harvested, the ripening process is slow or non-existent in non-climacteric fruits.
Non-climacteric fruits don’t have a dramatic increase in respiration (rise in the production level of CO2) during ripening, and don’t have endogenous ethylene, which accelerates the ripening process, like climacteric fruits (5).
How to pick a ripe watermelon from the market?
To choose a watermelon from the market, look for signs of ripeness. If the watermelon is ripe, the field spot should be a large, yellow patch (creamy, almost a butter-like yellow) on one side of the melon (6).
A number of subjective systems have been used by growers, including ground spot yellowness, senescent tendril next to the fruit pedicel, change in fruit wax (loss of shine), and thumping (dull sound when fruit are rapped with the knuckles) (3).
A few tips through which you can tell whether the watermelon is ripe or not are following;
Have a peek at its belly
The tern belly here refers to the field spot or the spot where it rested on the ground. The belly of a ripe watermelon is usually light green to creamy yellow referring to being buttery and not white which indicates an unripe watermelon.
Thump the watermelon
Using your knuckles, rap on the middle of the watermelon while holding it up to your ear, or flick it with your finger (like flicking a crumb off your shirt).
A ripe watermelon will have a hollow sound when knocked, which sounds more like a ‘plunk’. An unripe watermelon will have more of a higher-pitched sound, while an overripe one will make a ‘thud’ or a lower-pitched sound.
Sniff the watermelon
Pick your watermelon and carry it away from other melons so you don’t pick up the smell of other watermelons and give it a sniff. A ripe watermelon should smell slightly sweet like what it tastes like. But if you pick up an overly sweet smell it’s best to avoid that one as it might be overripe.
Squeeze it
Gently squeeze the side of the watermelon to see if there’s a bit of ‘give’ to it. The rind of the melon shouldn’t be soft, as the skin of some fruits get when ripe, but it also shouldn’t be hard as a rock with no give to it at all.
Pick the heavy one
Some say the heavier the fruit than its actual size the juicier it is. Watermelons also follow the same principle. You can pick a few good options and finalize the one that feels the heaviest to you.
Is unripe watermelon safe to consume?
Unripe watermelon is safe to consume, there is no general harm in eating unripe watermelon. Unripe watermelons just tend to be a bit bland and less flavorless than ripe watermelon. Unripe watermelon also has fewer nutrients, minerals and vitamins compared to fully ripe watermelon. Lycopene content of ripe watermelon is significantly higher (10 to 20%) than of unripe ones (4).
How to store watermelon?
To store watermelon, keep it at an 85-90 percent humidity environment and 47-55°F. Uncut watermelons will retain good quality for approximately 21-28 days under this condition. Watermelon stops ripening after harvesting. So pick a ripe watermelon, you may use the guide above. If you have picked an under-ripe watermelon, it is still edible, just flavorless, while an overripe watermelon will get mushy even before you cut it open.
If you have cut your watermelon it is best to store it in a refrigerator but store for no more than 2 to 3 days. Watermelons stored whole at low temperatures (5 °C) for 2 weeks lost about 15% of total lycopene, while lycopene content of cut watermelon cubes was reduced by 7 to 10% after 7 to 10 days storage at 2 °C. (4).
Conclusion
In this brief guide, we answered ‘how to ripen cut watermelon?’ Also, we have seen how to pick the perfectly ripe watermelon and a few ways you can store it.
Hopefully, you found this guide informative and helpful. In case of any queries or questions, please do let us know.
Citation
- Tadmor, Y. A. A. K. O. V., et al. Comparative fruit colouration in watermelon and tomato. Food Res Int, 2005, 38, 837-841.
- Abbaszadeh, Rouzbeh, et al. Nondestructive determination of watermelon flesh firmness by frequency response. LWT-Food Sci Technol, 2015, 60, 637-640.
- Vinson, Edgar L., et al. Use of external indicators to predict maturity of mini-watermelon fruit. Hort Sci, 2010, 45, 1034-1037.
- Perkins-Veazie, Penelope, et al. Watermelon: Lycopene content changes with ripeness stage, germplasm, and storage. Cucurbitaceae. Vol. 3. 2002.
- Paul, Vijay, Rakesh Pandey, and Girish C. Srivastava. The fading distinctions between classical patterns of ripening in climacteric and non-climacteric fruit and the ubiquity of ethylene-An overview. J food sci technol, 20132, 49, 1-21.
- Meyer, M. L. How to pick the perfect watermelon. University of Texas. 2020.
