Can you eat the peel of fruits? These kinds of fruits are not only edible, but also very nutritious!

It's the hot summer season, and it's time to eat fruit. When you are chewing watermelon or eating apples, are you curious about whether the fruit peels are edible? What nutrients do they contain? Today we will learn about the secrets of fruit peels.

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1. Scientific definition of fruit peel

The fruit peel we usually talk about is different from the scientific definition. In botany, peel is a special term that refers to the tissue of plant fruit. Many of the fruit pulps we eat are essentially peels, such as the pulp of apples and apricots, which are actually the mesocarp of plants. In addition, there are some fruits that look like plant fruits, but in fact the part we eat contains other tissue parts of the plant. For example, the sugarcane we eat is mainly the stem of the plant; the crystal clear lychee pulp is actually the aril of the lychee; the sweet strawberry, the edible part is mainly the swollen receptacle, and the small dots distributed on the surface of the strawberry are its real fruit.

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2. Fruit peels are nutritious

However, in life, we usually call the outermost part of the fruit the fruit peel, which generally refers to the exocarp of the plant, such as apple peel, banana peel, watermelon peel, etc. It is easy to ignore them when we eat fruit.

Since the flesh and the peel come from the same source, the peel will naturally have similar nutrients to the flesh. They also contain essential nutrients such as protein, carbohydrates and fat. Although the content is generally less than that of the flesh, it also has certain edible value. In fact, it is precisely because of its low calorie characteristics that the fruit peel can become a "weight loss food". For example, the calorie content of watermelon peel itself is very low, only about 35 calories per 100 grams, and it contains a large amount of pectin. Eating a small amount will produce a significant feeling of fullness.

Image source: Paixin Creative. More importantly, the fruit peel contains nutrients that the flesh lacks or does not have. For example, apple peel, citrus peel and grape peel are rich in dietary fiber.

According to the "Reference Intake of Dietary Nutrients for Chinese Residents (2013)", adults should consume 25-30 grams of dietary fiber every day, but the current average dietary fiber intake per capita in the world is only about 15 grams. About 60% of the ingredients in grape skins are dietary fiber, so "eating grapes without spitting out the skins" has a certain scientific reason - eating grapes with the skins can help us supplement a certain amount of dietary fiber.

Different fruit peels also have their own unique ingredients. Take grapes as an example. Grapes are rich in polyphenols, proanthocyanidins and other nutrients, which are natural antioxidants. The content of these nutrients in grape pulp is relatively low. The content of polyphenols in grape peels is about 20%~30%, while the content in grape pulp is only 3%~5%. If you remove the peel when eating grapes, it is equivalent to wasting about 95% of the polyphenols.

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Anthocyanin is a natural pigment that can remove free radicals in the body, inhibit lipid peroxidation and platelet aggregation, prevent diabetes and protect eyesight. Many fruit peels are rich in anthocyanin. The anthocyanin content of an apple peel is equivalent to that of three apple pulps, and the anthocyanin content of a complete pitaya peel is equivalent to that of five pitaya pulps.

The peel of citrus fruits contains not only refreshing natural essential oils, but also a special chemical called hesperidin, which has the functions of protecting capillaries and lowering cholesterol. The content of hesperidin in citrus peel is 25 times that in the pulp.

In addition, citrus fruits also contain a component called β-cryptoxanthin, which can prevent osteoporosis in the human body. The content of this substance in the peel is much greater than that in the pulp.

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3. There are some tips for eating fruit peels

Since eating fruit peels has so many benefits, how should we eat them? The simplest way is to wash the peels when washing the fruit, and eat the peels and flesh together, so that you get the most nutrition.

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However, you can also try some unique ways of eating it, such as cutting the watermelon rind into pieces to cook soup or mix it with cold dishes, or chopping the watermelon rind into dumpling fillings to make dumplings; the citrus peel itself is the raw material for making dried tangerine peel, so you can also try washing it and pickling it with salt and sugar, and eating it as fruit jam or dried fruit; the rich anthocyanins and betaine in the dragon fruit peel can be used as natural edible dyes. Crush it and collect the juice, and use it to color when baking pastries and biscuits. The bright red color is particularly festive; for grapes, you can add the peeled grape skins to sugar water and cook them together, then add the pulp and jelly, stir well and eat it, especially after being chilled. The icy and refreshing jelly has the fruity aroma of the grapes themselves, which is a good choice for cooling off in the summer.

4. Note! Not every fruit is suitable to be eaten with the skin

However, it is worth noting that not all fruit peels are suitable for consumption. For example, the peels of fruits such as durian, jackfruit, pineapple, kiwi, etc. are either too hard or have fuzz. I believe that most people would not choose to eat the peels of these fruits.

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Fresh persimmon peel contains a large amount of tannic acid, which can easily cause bloating, nausea, vomiting, and stomach stones, and is not suitable for consumption. Although banana peel is relatively rich in minerals such as potassium, magnesium, and calcium, unripe banana peel is prone to cause constipation, and ripe banana peel is easily damaged by bumps, friction, and low temperature during transportation, causing the banana peel to turn black, which will lead to a decline in taste and quality, and is more susceptible to pathogenic bacteria, so it is not recommended to eat too much.

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In addition, during the planting and transportation of fruits, pesticides or wax may be sprayed on them. The fruit itself may also form some inedible chemicals on the peel, and may also be contaminated with bacteria, viruses and other pathogens, so the fruit peel must be thoroughly washed before eating. Because the dietary fiber in the peel is relatively high, it is not recommended for the elderly, children and people with weak gastrointestinal function to eat too much fruit peel to avoid adverse reactions such as indigestion, nausea and vomiting, or abdominal distension and pain. The author of this article: Quasimodo by the River, a popular science worker.

Audit expert: Huang He

Source: Chongqing Science and Technology Museum

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