Table of contents
Watermelon (Citrullus lanatus) is a healthy, sweet and low-calorie thirst quencher - especially when consumed raw and organic. It has high levels of antioxidant lycopene and vitamin C (ascorbic acid).
Culinary uses of watermelon
When eaten raw, watermelon is a low-calorie refreshment, especially in summer. The pulp, seeds, and peel are edible as raw food. When consuming the peel, it is particularly important to clean the watermelon beforehand.
Sliced watermelon can be served as a vegan snack or aperitif without much effort. Fresh pieces of watermelon also taste good in muesli, fruit salad or punch. Watermelon juice mixed with a little water and served with ice cubes is a simple yet thirst-quenching and refreshing fruit drink. Boiled, reduced watermelon juice can be used as syrup for drinks or used for sweetening and refining creams. Sorbets, smoothies, shakes or cocktails made from watermelons not only taste delicious, they also look colorful. Vegan melon lassis or watermelon cakes may also be prepared. Even floury-tasting watermelons can be processed well.
A traditional Sicilian dessert is watermelon pudding (known as: gelo di miluni, gelo di anguria or gelo di melone). This consists of pureed watermelon, sugar, cornstarch, vanilla and (sometimes) cinnamon. Traditionally, the pudding is served with a topping of chopped pistachios and chocolate chips to mimic the appearance of pitted watermelon.
Watermelons are also suitable for savory dishes such as salads: e.g., with avocados, vegan feta made from tofu (can also be made from almonds or cashews), tomatoes, quinoa (or buckwheat, bulgur, couscous etc.) and lemon juice (lime juice). These can be made into a great dish in no time. Kernels or nuts such as hemp seeds, walnuts, pine nuts or pumpkin seeds refine the dish and fresh mint leaves, grated lemon zest, salt and pepper round off the salad perfectly. A gazpacho (cold soup) with raw watermelon or cantaloupe is definitely worth trying in raw food cuisine. In this case, the sweet taste of melons meets sour vegetables such as raw cucumbers or tomatoes and hot spices such as chili and pepper. You can also use watermelon instead of the honeydew suggested in the vegan carpaccio recipe and refine it with rocket.
Vegan recipe for watermelon poke bowl
Ingredients (for 4 people): 1 kg raw watermelon (organic, seedless, peeled), 2 tbsp tamari or soy sauce, 2 tbsp sesame oil, 4 tbsp rice vinegar, 1 spring onion, 4 tbsp sesame seeds.
Alternatively, you can reduce the amount of tamari or soy sauce a little - or replace it with sliced nori for the marinade. Rapeseed oil has a much better fatty acid profile than sesame oil or tahini, provided the taste of sesame obtained by adding the seeds is sufficient.
Procedure: Cut the watermelon into 2-3 cm pieces and set aside. Finely chop the spring onion. In a bowl, whisk together the ingredients for the marinade (sauce, oil, and vinegar). Pour the marinade over the watermelon cubes and stir gently. Scatter chopped spring onion and sesame seeds over the marinated sliced melon. Put everything in a bowl and leave covered in the fridge for at least 12 hours. A Poke-Bowl (Poké-Bowl) is prepared with cooked rice and vegetables (raw), arranged neatly next to each other, in a bowl: Finely chopped avocado, cucumber, red cabbage, etc. are ideal. The marinated watermelon imitates 'vegan tuna'. This is a Hawaiian recipe where raw fish is used traditionally.
To find vegan recipes with watermelon follow the reference: "Recipes that have the most of this ingredient".
Not only vegans and vegetarians should read this: A Vegan Diet Can Be Unhealthy. Nutrition Mistakes |
Purchasing - storage
Watermelons can be purchased from large supermarket chains. Organic watermelons are available in most supermarkets. Locally grown watermelons are also available during the season at the farmers’ markets.
When buying a watermelon, make sure it is well ripe. Unlike cantaloupes, ripe watermelons do not emit any scent. Yellow ground spots indicate where the watermelon lay on the ground. A prominent yellow spot indicates that the watermelon was harvested when fully ripe. The rind should be firm and not yield to finger pressure.2 Ripe watermelons make a hollow sound when the rind is tapped. Connoisseurs even perceive a vibration. In addition, ripe melons are somewhat heavier than the unripe ones.11 If a watermelon has been cut open, you can tell that it is ripe by the intense color of the flesh and a small amount of white fruit underneath the green skin.
Varieties with yellow flesh are occasionally found in the supermarket.2 These are also known as pineapple melons. Cracks and "holes" in the pulp (called hollow hearts) can be caused by natural "disorders of growing" and are not usually an indication of the use of chemical regulators.18 More information on this topic can be found in the section Ecological Footprint - Animal Welfare.
Storage tips
Fresh, whole watermelons will keep for about 2-3 weeks at 12-15 °C and 85-90 % relative humidity. When kept in room temperature they can be stored for 1-2 weeks. The flesh loses color at temperatures < 10 °C, which is why it is not stored in the refrigerator. Watermelons do not ripen after harvest, but are sensitive to ethylene (ethene), a ripening hormone that emanates from climacteric fruits (e.g., apples, bananas or kiwis). When stored next to such fruit, the pulp acquires a soft, mealy consistency (some find it sandy).2
How should you store a cut watermelon? Slices of melon that have been cut spoil quickly, which is why they should be eaten on the same day if possible. The raw flesh of watermelons is low in acid and offers a good breeding ground for harmful microorganisms such as Salmonella, Listeria or Enterohemorrhagic Escherichia coli (EHEC). These bacteria contaminate the pulp either directly when cutting it open (pathogens come from the skin onto the pulp) or via dirty hands or kitchen utensils (knife, chopping board). Good kitchen hygiene is very important to prevent infections and it is advisable to eat the melon pieces quickly or to keep them refrigerated. The Federal Institute for Risk Assessment (BfR) recommends disposing of the fruit if it is left uncooled for several hours.3
Ingredients - nutritional values - calories
100 g of raw watermelon has 30 kcal. Therefore, 1 kg of watermelon has about 300 calories.
What is a watermelon made of? The juicy pulp consists of around 91 % water and around 6 % sugar. Despite its sweetness, watermelon contains relatively little sugar. In comparison, bananas have a very high sugar content with 12 g of sugar per 100 g. Watermelon has 0.61 g protein and 0.15 g fat per 100 g, and thus it is very low in protein and almost fat-free. It contains 1.6 g of fiber which cover 1.6 % of the daily requirement.4
A raw watermelon has 8.1 mg of vitamin C per 100 g, which is 10 % of the daily requirement. Rhubarb (8 mg/100g) and bananas (8.7 mg/100g) have comparable amounts of ascorbic acid. At 93 mg/100g, kiwis contain a high proportion of this antioxidant vitamin.4
Watermelon contains 112 mg/100g of potassium (6.0 % of the daily requirement). Pineapples (109 mg/100g) and apples (108 mg/100g) have a similar amount of potassium. A fruit high in potassium is raw jackfruit at 448 mg/100g.4
The vitamin A content, as RAE, is 28 µg/100g (4.0 % of the daily requirement). This is comparable to that of black elderberries (30 µg/100g) and guava (31 µg/100g). Sugar melons like cantaloupe have a much higher vitamin A content of 169 µg/100g. This corresponds to 21 % of the daily requirement.4 We absorb vitamin A from plants as provitamin A in the form of carotenoids. Watermelons contain the carotenoid lycopene, which is responsible for the red color and is one of the antioxidants,15 but which has no provitamin A activity.5
You can find the total ingredients of watermelons, the coverage of the daily requirement and comparison values with other ingredients in our nutrient tables. In the article Nutrients explained you will get a detailed insight into the topic.
Health effects
Do watermelons have any health effects? Watermelon is a low-calorie thirst quencher, and the most common cultivated form with red fruit pulp has a high lycopene content.15 Antioxidants such as the carotenoid lycopene neutralize free radicals and reduce oxidative stress. Lycopene has a positive effect on cardiovascular or neurodegenerative diseases and some types of cancer. However, the status quo of research (as of 2013) shows that most people's dietary intake is inadequate. Unlike other micronutrients, lycopene has no recommended or maximum daily intake.5
A double-blind, placebo-controlled study from Brazil shows that watermelon extract reduces systolic and diastolic blood pressure. Citrulline is responsible for this and the body converts citrulline to arginine. Arginine has vasodilating effect due to which blood can circulate more easily and blood pressure is lowered.6
Dangers - intolerances - side effects
Is watermelon unhealthy? Diabetics are often advised not to eat watermelons because they have a high glycemic index. The glycemic index (GI) shows how much a food affects blood sugar levels. A high GI means that blood sugar shoots up quickly. Therefore, diabetics should avoid food with high GI. However, the GI alone leads to a distorted perception. The GI was developed as a laboratory parameter for research purposes and is not very practical for everyday nutrition. The number describes the response to ingesting 50 g of carbohydrates of a particular food rather than the response to 50 g of the food. Therefore, the term glycemic load (GL) was introduced, which takes into account the carbohydrate density. Actual blood glucose response is dependent on a variety of factors, so GI and GL should only be used as a guide.16
The glycemic index of watermelon is approximately 7217 (7516). However, in order to achieve the effect of this calculated GI, one would have to eat around 800 g of watermelon. A portion of watermelon is about 120 g and has a low glycemic load. Therefore, consumption of watermelon in moderate amounts is also possible for diabetics.17
Harmful microorganisms can multiply very quickly on cut watermelons at too high temperatures due to the low-acid environment (see above section on storage). This can lead to infections.3
Watermelon allergy is rare but can occur. Symptoms include sore throat, stomach cramps, nausea, diarrhea and rash. In addition, cross-reactions with grass pollen allergy are possible.7
Traditional medicine - naturopathy
Watermelons are said to have a diuretic and kidney-cleansing effects.2
Ecological footprint - animal welfare
Conventional farming may use growing regulators to influence the size of fruits and vegetables. An active ingredient (forchlorfenuron) gained notoriety through reports of exploding watermelons in China where excessive use of this agent was suspected (2011). But cracks in watermelons are not always due to forchlorfenuron. "Holes" (so-called hollow hearts) or cracks can also be caused by insufficient pollination, and natural disorders in growing.18 Studies show that when forchlorfenuron is used properly in watermelons, only minimal residues of the agent can be detected (around 0 -4.5 μg/kg).19 If you eat these watermelons, you are far from reaching the maximum residue limit set by the EU of 0.05 mg/kg. Forchlorfenuron is also permitted for use in conventional agriculture in some EU countries (GR, ES, FR, IT, PT).20
Residue analyses by the Austrian NGO Global 2000 from 2020 showed that of the 118 conventional farming products (fresh vegetables and fruits) tested for pesticides, all samples had pesticide residues. This study looked at 151 different pesticides - 54% of the substances detected had properties that were harmful to health (carcinogenic, reprotoxic, mutagenic or endocrine disrupting). None of these products were classified as presenting an acute health risk, although 19 of them exceeded the allowed maximum limit.22
Organic farming tries to avoid pesticide residues or to keep them as low as possible, A 100% residue-free status is almost impossible if one includes heavy metal pollution, drift, cross-contamination or contamination during storage or transport. In organic farming and thus also in the production of organic watermelons, the use of synthetic chemicals or genetically engineered products is not permitted.23
In general, improper use of crop protection products is harmful to the most important pollinator of melon plants, the honey bees. They are exposed to pesticides, either directly or through pollen collection, and overexposure can result in physical impairments or weakened immune responses.21
Watermelon cultivation consumes large volumes of water. Water consumption per fruit is up to 400 L. This can lead to massive lowering of the groundwater level and environmental problems in the producing countries.12 Watermelons from local or nearby production areas should be preferred so that there is a smaller ecological footprint than products from other continents. However, the large water footprint remains an issue. We recommend a moderate and seasonal indulgence.
Worldwide occurrence - cultivation
The region of origin of the cultivated watermelon (Citrullus lanatus var. lanatus) was not clear for a long time. In addition to South Africa and West Africa, the north-eastern part of Africa was also discussed as the place of origin. Recent genetic studies (2021) indicate that the Sudanese kordofan melon (Citrullus lanatus ssp. cordophanus) is the closest related species to the domesticated watermelon.8
Today, the cultivated varieties are grown worldwide in the tropics, subtropics and in the Mediterranean region.
Growing wild
The cultivated watermelon (Citrullus lanatus var. lanatus) cannot be found in the wild. But there are also some wild watermelons, such as the Tsamma melon, lemon melon or cow melon (Citrullus lanatus var. citroides), which are found in the wild in Africa. These wild watermelons are very bitter and are also cultivated here. The Tsamma melon is now also classified to the species Citrullus amarus. However, according to a 2014 study, this is not the original form of the watermelon we know.13
Cultivation - harvest
Young watermelon transplants should be grown from seeds from around April. The transplants are in a compost-enriched bed (sandy, humus-rich soil) or in a large pot in June. It is important that the temperature, even at night, is more than 12 °C. The distance between plants should be at least 1 m, as it forms far-reaching tendrils. A glass house or poly tunnel offers the plant the necessary warmth. Otherwise, a sunny but wind-protected place is suitable. Watermelons need a lot of water, especially when fruiting. Water only the root trunk and not the leaves to avoid risk of mildew (fungus). Depending on the variety and weather, watermelons need 60-90 days to be ready for harvest. In addition to the dull sound of the melon, the withering leaves also show the degree of ripeness.14
How much does a watermelon weigh? Cultivated watermelons can reach a weight of up to 100 kg, but they usually weigh between 4 and 25 kg. Smaller mini watermelons are between 1.5 and 2 kg. Seedless watermelon hybrids are now available.2
Additional information
Is the watermelon a fruit or a vegetable? Melons belong to the pumpkin family and are therefore assigned to the fruits. They are annual plants that form climbing shoots up to several meters long. Melons are divided into watermelons (species: Citrullus lanatus) and sugar melons (species: Cucumis melo). The latter also includes the popular honeydews and cantaloupes. Botanically, muskmelons are more closely related to cucumbers than to watermelons.
The taxonomy is not always clear. The cultivated form of watermelons is assigned to the subspecies Citrullus lanatus ssp. vulgaris (Schrad.) Fursa and occasionally the variety var. vulgaris. The dessert watermelon described here can be found under Citrullus lanatus, but also with the addition of the variety var. lanatus (Thunb.) Matsum. & Nakai. Occasionally the term Citrullus lanatus ssp. vulgaris var. lanatus can be found.
The flesh of the watermelon is often red, but there are also green, yellow (also called pineapple melon), white and orange varieties. The seeds also have different colors (black, brown, red, green, white), shapes and sizes.
Alternate names
The name desert watermelon is used to distinguish bitter subspecies of watermelon, which are usually only grown for their seeds. Pineapple melon often refers to the yellow-fleshed watermelon, but not exclusively. An earlier Latin synonym of Linnaeus was Cucurbita citrullus, today Citrullus vulgaris is also a common term.
Bibliography - 20 Sources
2. | BLE Bundesanstalt für Landwirtschaft und Ernährung. Wassermelonen. Produktinformation. Flyer März 2021. |
3. | BfR Bundesministerium für Risikobewertung. Melonen können krankmachende Keime übertragen. 22/2013. |
4. | USDA United States Department of Agriculture. |
5. | Cruz Bojórquez RM, González Gallego J, Sánchez Collado P. Revisión. Propiedades funcionales y beneficios para la salud del licopeno [Functional properties and health benefits of lycopene]. Nutr Hosp. Februar 2013;28(1): 6–15. |
6. | Massa NML, Silva AS, Toscano LT et al. Watermelon extract reduces blood pressure but does not change sympathovagal balance in prehypertensive and hypertensive subjects. Blood Press. August 2016;25(4): 244–8. |
7. | Pastor C, Cuesta-Herranz J, Cases B et al. Identification of major allergens in watermelon. Int Arch Allergy Immunol. 2009;149(4): 291–8. |
8. | Renner SS, Wu S, Pérez-Escobar OA et al. A chromosome-level genome of a Kordofan melon illuminates the origin of domesticated watermelons. PNAS [Internet]. 8. Juni 2021; 118(23). |
11. | LID Landwirtschaftlicher Informationsdienst. Süsse Exotin - die Schweizer Melone. 2021. |
12. | Pini U. Das Bio-Food Handbuch. Kleemann: Hamburg, Potsdam. 2014: 472. |
13. | Chomicki G, Renner SS. Watermelon origin solved with molecular phylogenetics including Linnaean material: another example of museomics. New Phytologist. 2015;205(2): 526–32. |
14. | Plantura.garden.de Wassermelone pflanzen: Experten-Tipps für den Anbau. |
15. | Sulaiman F, Ahmad Azam A, Ahamad Bustamam MS, et al. "M........." Profiles of Red and Yellow Watermelon (Citrullus lanatus) Cultivars Using a 1H-NMR Metabolomics Approach. Molecules 2020;25(14): 3235. |
16. | Diabetes-austria.com Glykämischer Index (pdf). |
17. | Medicalnewstoday.com Is watermelon high in sugar for people with diabetes? Diet tips and nutrition. 2021. |
18. | Trandel MA, Perkins-Veazie P, Schultheis J. Predicting hollow heart incidence in triploid watermelon (Citrullus lanatus). HortScience. 2020;55(12): 1926-1930. |
19. | Valverde A, Piedra L, Aguilera A, Boulaid M, Camacho F. Analysis and residue levels of forchlorfenuron (CPPU) in watermelons. Journal of Environmental Science and Health, 2007 Sept-Oct;42(7): 801-807. |
20. | Europäische Kommission. EU Pesticides database. 2022. |
21. | Pacifico dSI, Oliveira FAS, Pedroza HP, Gadelha ICN, Melo MM, Soto-Blanco B. Pesticide exposure of honeybees (Apis mellifera) pollinating melon crops. Apidologie. 2015; 46: 703-715. |
22. | Global 2000. Statusbericht chemischer Pflanzenschutz. Obst und Gemüse. Wien. 2020. |
23. | Bio Suisse. Haltung von Bio Suisse zum Thema „Rückstände“. 2019. |
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