Fruits are similar to vegetables in terms of nutrient composition and nutritional value, and are an important source of vitamins and inorganic salts for the human body.
A variety of fruits generally contain more sugar and fiber, but also contains a variety of biologically active special substances, and thus has a very high nutritional value and health benefits. It contains the following components:
1. Sugar:
Sugar prevalent in fruits are sucrose, glucose, fructose.
Because of the different varieties, the amount and type of sugar contained are different, such as apples, pears and other fructose; citrus, peaches, plums, apricots contain more sucrose; grapes contain more glucose.
The sugar content of various fruits is generally between lO% and 20%, fruit ripeness is high, the sugar content is also high.
More than 20% sugar content of jujube, coconut, banana, hawthorn and other fresh fruits; lower sugar content of fresh fruits are strawberries, lemons, pears (Shanghai wood pear, Gansu sour pear, Shandong Longkou long handle pear, etc.), peaches (Gansu white powder peach, golden peach), prunes and so on.
The sweetness of the fruit in addition to the sugar content, but also by the fruit of other components, such as organic acids, sugar-acid ratio of fruit sweetness is also large, tannin-containing increase, the fruit's acidity is large, sweetness is small.
2. Organic acids:
Organic acids in fruits are mainly malic acid, citric acid and tartaric acid, etc., often referred to as fruit acids, which are the source of fruit acidity.
Organic acids and sugar to form a sweet and sour mixture of special flavors, in the taste of sour taste has the role of reducing sweetness.
So, in the test of the flavor of the fruit to determine the ratio of sugar and acid, the ratio is high is sweet, the ratio is low is sour.
3. Pectin substances:
Pectin is a universal polysaccharide compounds in plant tissues, is the main component of the cell wall, but also a natural, without any toxic side effects of soluble dietary fiber.
The original pectin, pectin, pectic acid in three different forms present in the fruit tissue, immature fruit in the presence of most of the original pectin.
It is insoluble in water, exists in the cell wall of the gelatinous layer, the cells are tightly stuck together with each other, so that the fruit appears solid and brittle hard.
4. cellulose:
Constitutes the main component of the fruit cell wall and transport tissue, in the epidermal cells of the fruit, cellulose and more with pectin, lignin combined into a composite cellulose, the fruit play a protective role.
The content of cellulose in the fruit is about 0.5% to 2%, if too much, then the meat is thick, thick skin and tendons, edible quality is low.
5. Vitamins:
Fruits mainly contain vitamin C and B vitamins.
Fruit is the main source of vitamin C, fresh dates contain the most vitamin C, followed by citrus fruits,
Fruits in the B vitamins content is not much, including grapefruit, orange, fresh dates contain more B vitamins.
Fruits also contain a small amount of vitamin A.
6. pigmentation:
The epidermis of fruits shows different colors due to the differences in the type and amount of pigments contained, the color of fruits changes with the change of growing conditions or the change of ripeness.
Colors are divided into fat-soluble and water-soluble due to their solubility properties.
7. Aromatic oils:
Fruits in the flavor, from its contained in a variety of aromatic substances, these aromatic substances are oily, so it is also known as volatile oils, they are often mixed with a variety of chemical components.
Aromatic oils are mostly found in the oil glands of the rind, and less in the flesh.
The aroma of fruits stimulates the appetite and helps the body absorb other substances, and some aromatic oils have antiseptic powers.
8. Inorganic salts:
Fruits are richer in inorganic salts and are the main source of inorganic salts in the diet.
Mainly contains calcium, phosphorus, potassium, iron, magnesium and other elements, of which olives, citrus, hawthorn and other calcium, grapes, apricots, peaches, hawthorn, strawberries and other iron, bananas, strawberries and other phosphorus.
And most of the fruits are metabolized in the body to produce more alkaline elements.
Expanded Information:
1. unripe fruit should not eat:
In the unripe fruit, most contain oxalic acid and benzoic acid and other components, in the human body is difficult to oxidize the decomposition of metabolism after the product is still acidic, which will destroy the body's normal weak alkaline environment, leading to the physiological function of the impact.
In addition, some fruits such as bananas, apricots, etc., in the unripe, which will contain toxins, which is also harmful to the human body.
Therefore, it is not advisable to eat unripe fruits.
2. Eat fruit to peel:
In order to control pests and diseases, fruit growers often use a variety of pesticides in the growth process of fruit trees, some pesticides can be soaked and residue in the wax layer of the fruit skin, so pesticide residues in the skin is much higher than that in the flesh.
And these pesticide residues in the rind are difficult to wash off with water.
If you eat without peeling, for a long time, you will have vomiting, diarrhea, anorexia, chest tightness, skin allergies and other reactions, or damage to the stomach and intestines, a health hazard.
In addition, most of the fruit peel with bacteria, viruses and parasite eggs and other pathogenic microorganisms, if the cleaning is not thorough enough, once eaten into the stomach, will cause dysentery, ascariasis and other diseases.
3. Eat fruit to rinse your mouth:
Most fruits contain more sugar, these sugars and embedded in the teeth, gum gap in the fruit residue will gradually ferment in the oral cavity acid, a long time will corrode the teeth, very easy to form dental caries, and ultimately produce cavities.
Therefore, eating fruit does not clean the mouth, on the contrary, after eating fruit to pay attention to rinse mouth, in order to remove the sugar in the mouth.
Baidu Encyclopedia-Fruit