What foods contain water. Tap water or tap water
Water, not being a nutrient itself, is vital as a body temperature stabilizer, nutrient carrier ( nutrients) and digestive waste, a reagent and a reaction medium in a number of chemical transformations, a biopolymer conformation stabilizer and, finally, as a substance that facilitates the dynamic behavior of macromolecules, including the manifestation of their catalytic properties.
Water– important component food products . It is present in a variety of plant and animal products as a cellular and extracellular component, as a dispersing medium and solvent, causing their consistency and structure and affecting appearance, taste and stability of the product during storage. Through its physical interaction with proteins, polysaccharides, lipids, and salts, water contributes significantly to the texture of foods, shaping their consistency. The water content of foodstuffs varies widely.
Table 6 – Moisture content in foods
In food products, water can be in a free and bound state. free water in the form of tiny drops is contained in the cell sap and intercellular space. It contains organic and minerals. When dried and frozen, free water is easily removed. The density of free water is about 1 g / cm 3, the freezing point is about 0 o C.
Bound call the water, the molecules of which are physically and chemically bound to the hydrophilic groups of proteins and carbohydrates. Bound water has anomalous properties, does not dissolve salts, freezes at a temperature of -40 ° C and below, has a density of 1.2 g/cm 3 or more. Drying and freezing bound water is not deleted.
During storage and processing of food products, water can change from one state to another, causing changes in the properties of these goods. So, when boiling potatoes and baking bread, part of the free water passes into a bound state as a result of swelling of the backs, gelatinization of starch. When thawing frozen potatoes or meat, part of the bound water goes into a free state. Free water creates favorable conditions for the development of microorganisms and the activity of enzymes . Therefore, foods containing a lot of water are perishable.
The water content (humidity) is an important indicator of product quality. Its reduced or increased content of the above-established norm worsens the quality of the products. For example, flour, cereals, pasta with high humidity deteriorate quickly. A decrease in moisture in fresh fruits and vegetables causes them to wilt. Water reduces energy value product, but gives it juiciness, increases digestibility.
Control questions:
1. Why does water have an abnormally high heat capacity?
2. What does the water status chart indicate?
3. What is the triple point of water?
4. What role does water play in digestion?
5. What functions does water perform in food products?
6. What is the difference between bound water and free water?
7. What does the term "activity" of water mean?
8. What processes take place in products with high water activity?
9. What processes can take place in products with low activity?
10. What processes take place in products with intermediate water activity?
11. What methods are used to increase the content of bound water in products?
Literature: 1- With. 461-491.
Bibliography:
1. Food chemistry / Nechaev A.P., Traubenberg S.E., Kochetkova A.A. and others. Ed. A.P. Nechaeva. - St. Petersburg: GIORD, 2004.- 640 p., S. 8-16
2. Skurikhin I.M., Nechaev A.P. Everything about food from the point of view of a chemist. - M .: Higher School, 1991. - 287 p., S. 3-7.
3. Dubtsov GG Commodity science of food products. - M .: Publishing House "Mastery", 2001.-263 p., S.3-95.
4. Pavlovsky P.E., Palmin V.V. Biochemistry of meat. - M .: Food industry, 1975.- 387 p.
5. Antipova L.V., Zherebtsov N.A. Biochemistry of meat. - M.: Food industry, 1991. - 372 p.
6. Gorbatova K.K. Biochemistry of milk. – M.: Food industry, 1986.- 275 p.
7. Dmitrichenko M.I., Pilipenko T.V. Commodity research and examination of edible fats, milk and dairy products. - SPb., PETER, 2004.- 350 p.
The value of water for the body
Water is a very important nutrient.
Water makes up two thirds of the weight of the human body. It is an essential component of life support. Lack of water is more dangerous to life than lack of food. Loss of 15% water by the body leads to death.
Water is an indispensable component of the life of the body. Water is present in every cell of the body, it is involved in all processes, from those in which its presence is obvious (blood circulation), and ending with the solid structures of the cell. Blood consists of 83% water, skeleton - 22%, brain - 75% water, muscles - 76%. Water is an excellent medium for the dissolution and transport of organic and inorganic substances, metabolic reactions. The process of digestion and absorption of nutrients into the blood takes place in a liquid medium. With the help of water, waste products, toxins and toxins are removed from the body. Thanks to water, most of the functions of the body are carried out.
Man has two main sources of water:
- metabolic water - formed as a result of the oxidation of proteins, fats and carbohydrates in the body
- water from food and drink.
Water balance
Water balance the body must always remain unchanged, that is, the amount of water entering it must be equal to the amount of water that the body loses. Water balance is controlled by the body itself. When more water is supplied than is needed, it is not used and is excreted in the urine.
The adult body needs at least 2.5 liters of water per day to compensate for natural losses with urine, respiration and sweat (the indicator depends on the weight of the person and physical activity). In some cases, it is necessary to increase water consumption: heat and air humidity (1-2 glasses a day); visiting the bath; lactation; medication use; colds disease(the more you drink, the better); excess weight; diet, alcohol consumption; heavy physical work; playing sports (for land sports: 0.5 liters of water half an hour before training and 0.5 liters after, drink in small sips during training, first holding the water in your mouth a little).
If there is not enough water, then this will lead to too much stress on the kidneys, which will have to work harder in order to concentrate urine and excrete a small amount water as much toxic waste as possible (with a lack of water, urine becomes darker). In an organism that regularly experiences a lack of water, the rate of metabolic processes decreases, fats cease to be broken down, and toxins cannot be removed from the body in a timely manner and begin to accumulate. Lack of water in the body gradually leads to disruption of all internal organs. water scarcity causes fatigue, drowsiness, depression, irritability, headaches, unreasonable impatience, chronic pain in the stomach and intestines. Outwardly, water deficiency can manifest itself in extra pounds, deterioration of the condition of the hair, notes and peeling of the skin. Lack of water is a potential opportunity for the development of hypertension. The brain cells are the most sensitive to lack of water.
The largest amount of water is found in milk, yogurt, juices, soups, vegetables and fruits. The water content in bread is about 50%, in cereals - 80%.The product's name |
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Nuts, sunflower seeds |
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Candies, halva |
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Peas, lentils, beans, soybeans |
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dried mushrooms |
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Butter, margarine |
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Cereals, flour, drying, bagels |
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Raisins, apricots, dried peaches |
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Marshmallow, honey, marshmallow |
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Biscuit cake, marmalade |
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Dried apricots, prunes, dried apples |
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Sweets, bread |
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Semi-smoked sausage, sausages, sausages, ham |
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Pork, goose, duck |
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Boiled sausage, stew |
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Lamb, beef, veal, rabbit, chicken, liver |
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Fish, seafood |
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Mushrooms fresh |
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Yogurt, kefir, milk, curdled milk, fermented baked milk, cream, sour cream 10% |
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Vegetables, fruits, berries |
What water is better to drink
Tap water or tap water
Now, few people in our country consume tap water in its raw form. tap water undergoes filtration, coagulation, chlorination in the purification process. Chlorine kills many microbes, but when interacting with organic matter, it forms unhelpful compounds. In tap water, the concentration of iron, chlorine, and metal salts can sometimes be exceeded. Hard water contains excess magnesium and calcium. Accumulating in the body, metal salts can cause diseases of the kidneys, liver, and skeletal system.In addition, the condition of water pipes is often not ideal, and, passing through them, water can get secondary pollution. Therefore, it is better to refrain from the systematic use of large amounts of water from the tap without pre-treatment. improve quality tap water allows the installation of coarse filters in apartment pipes (they get rid of large fractions - sand, rust, etc.) and fine filters (designed to retain rust, chlorine, heavy metal salts).
filtered water
Modern industry offers a wide range of water filters: stepped for running water(remove mechanical impurities, chlorine and organochlorine compounds; partially remove pesticides, manganese, iron, heavy metals, oily products, hardness salts, trichloromethane, do not remove bacteria, viruses, chlorides, nitrates, nitrites, fluorides at all), filter jugs (first water passes through a fine mesh, then through a layer of absorbent, such as pressed activated carbon or shungite; jug filters do not retain organics), filters with a reverse osmosis system (filters water at the molecular level, makes water distilled), filter nozzles on a tap (usually only mechanically purify water), filters for softening water (ion exchange filters, hardness salts are removed ), mechanical cleaning filters.It is very important to change the cartridges in a timely manner. If they get clogged, bacteria start to multiply in them.
Boiled water
Boiling relieves water from pathogenic bacteria and microbes, from chlorine, hydrogen sulfide, makes it softer. If boiled water will stand for some time, then bacteria will start in it again.When boiling, the microstructure of water changes, it becomes tasteless.
Do not boil water again.
Before boiling water, it is better to get rid of unwanted impurities (by filtration or settling).
Settled water
Settling of water- Very good method cleaning, when using which suspended solids (heavy chemical compounds, salts, bleach and other elements) gradually settle to the bottom of the tank. Water should be defended for at least 5-6 hours in a glass open container. You can use the "upper" 2/3 - 3/4 of the volume of settled water. For better cleaning The "upper" water can be boiled.It is wrong to boil first, and then defend the water.
bottled water
For the manufacture of bottled drinking water (TU 0131) water is taken from any source (water supply, river, artesian well) and undergoes serious purification and enrichment with minerals. There is bottled water of the first category and the highest category, the latter contains everything necessary for a person trace elements in the amounts specified in SanPiN, developed in 2002.Distilled water
Distilled water- purified water, practically free of impurities and foreign inclusions. Obtained by distillation in distillers and reverse osmosis.Water contains a complex complex of substances dissolved in it, most of which are useful. It has been proven that a liter of drinking water must contain at least 30 mg of calcium and 10 mg of magnesium - otherwise the water-salt balance is disturbed. For consumption, distilled water is too depleted, as a result of which the body will make up for the alkaline need at the expense of its own bone tissue. Distilled water removes trace elements from the body, so you can not drink it all the time.
Sparkling water
IN sparkling water oxygen is artificially replaced by carbon dioxide. Carbonated water is good for toning and refreshing, but the carbon dioxide it contains irritates the stomach, causing heartburn and belching. In general, you can not drink soda for people suffering from gastrointestinal diseases.Healthy people can drink soda very moderately, because to get rid of carbon dioxide the body needs a lot of fluid.
Mineral water
mineral water drink is good. It eliminates salt deficiency during dehydration.Mineral water is divided into:
- dining room - up to 1 gram per liter,
- medical table - 1-10 grams per liter
- medicinal - over 10 grams per liter
It is better to choose natural mineral water with a natural balance of salts. The water extracted from the source, which has not been subjected to any treatment, is labeled GOST 13273-88, the label should also indicate the name of the source and the number of the well. A bottle of artificially mineralized water will be marked TU 9185.
Nothing quenches thirst as well as plain water. Fruits are also well suited for solving this problem, since they contain a lot of this liquid - on average, about 80%. In addition, the gifts of nature are a source of fiber, many vitamins and minerals. However, do not forget that they contain a lot of sugar, so it is better to eat no more than 3 servings per day. So,
Which fruits contain the most water
Orange
It perfectly quenches thirst and refreshes, is a generous source of vitamins and minerals - not only C, but also calcium. Two oranges can supply it to the body as much as a glass of milk. Instead of drinking shop juice, squeeze it yourself from fresh oranges - it's much healthier and tastier. Plus, it won't be artificially sweetened and is a better thirst quencher. Do it.
Oranges should be eaten whole because most of the nutrients are found in the white skin that covers the fruit. It is a rich source of pectin and vitamin P, which helps lower bad cholesterol levels and improves digestion.
Melon
This fruit is 91% water. Melon juice is great drink for hot days, and the fruit itself - indispensable component fruit salads. Not everyone knows that melon can also be served as a salty treat. For example, Italians serve it wrapped in parma ham. Eating a melon is not only worth it unique taste, but also because it is a rich source of potassium, vitamins A and C and beta-carotene, which has an invaluable effect on skin condition.
Watermelon
No wonder in English language watermelon is called watermelon: it is 92% water. Everything else is sugar, but you should not be afraid of it if it is not exceeded. daily portion fruit consumption. True, this berry has a high glycemic index but its glycemic load is low.
Some people argue that there is nothing more refreshing than a serving of fresh chilled watermelon on a hot summer day. In addition, due to its sweet taste, it for a long time satisfies the need for sweets. You also need to remember its strong diuretic effect.
Strawberry
Local berries are best, so it makes sense to use "native" resources for as long as possible. Strawberries are a rich source of vitamins, in particular C, A, B1, B2 and PP. It is recommended for people who want to lose weight. Mineral salts contained in berries improve metabolism, and pectin cleanses the intestines. In addition, they have the "ability" to cleanse the body. Strawberries are great for refreshing as a light snack or as an ingredient in smoothies.
Apple
85% of apples are water. In addition, they are sweet, juicy, crispy. What nutrients can be found in them? First of all, these are pectins, which have positive impact on digestion, as well as vitamin C, A, magnesium, potassium, silicon. Although the most valuable fruits in fresh(it is in this case that they are the richest source of both water and nutrients), apples feel great in desserts, in thermally processed dishes.
Pear
Ripe, sweet, melt-in-your-mouth fruits are 85% water. But we must remember that as it ripens, the amount of pectin and fruit acids decreases, but the sugar content increases. Pears contain a lot of potassium, phosphorus, magnesium, calcium, zinc, iron, iodine and boron. They are a source of many vitamins: A, B1, B2, B5, PP and fiber. Contrary to popular belief, pears are not a hard-to-digest food and, importantly, very rarely cause allergies.
Plum
Plums are full of antioxidants that have anti-inflammatory effects. It is also a rich source of fiber, which stimulates intestinal motility. Plum fruits are recommended for people with high cholesterol and high blood pressure. But you have to remember that it's pretty high-calorie snack: 100 grams - 80-120 kcal. Plum contains about 83% water - as well as cherries and grapes.
Currant
Currants, especially black and red currants, are one of the richest sources of vitamin C, pectin and vitamin PP. Berries neutralize the action of free radicals, have a mild laxative effect. The skin of blackcurrant contains antibacterial substances - tannins, which kill E. coli bacteria that contribute to intestinal diseases. Also, these substances have an anti-inflammatory effect, have a beneficial effect on the heart, and gently lower blood pressure.
Cherries
These berries are 80% water. Their systematic use has a beneficial effect on the skin, tightens and smoothes it. Although this culture is considered a “relative” of cherries, cherries have much more iodine, calcium and iron. It is best to eat berries raw, although they are often used for compotes, jams or jelly.
Mango
This tropical fruit is one of the healthiest fruits in the world. The mango menu should be present not only because of a large number water, but also because it is a rich source of beta-carotene.
If you have little idea how to eat mango, know that the fruit makes a wonderful variety in salads and is one of the main components of the traditional indian drink- lassi. If you mix mango with natural yogurt, skimmed milk, a small amount of sugar and saffron, you get a very refreshing drink with a unique taste.
You have probably already heard that you should drink eight glasses of water a day. In fact, this is not confirmed by science: a person needs liquid in any form, and not just water. If you sweat heavily on a regular basis, you need to drink more. If you eat a lot of foods containing water, you can drink less. Fluid deficiency is a big problem. Water helps control weight, cleanses the body of toxins, and helps the kidneys function. Studies show that it is even needed for good concentration. Nevertheless, it is important to know: one fifth of the volume of liquid comes from food. Eat water-rich foods to hydrate your body.
Cucumber
Cucumbers have an impressive liquid content of about ninety-five percent. In addition, this vegetable is high in potassium, which helps prevent heart attack. Cucumbers also contain anti-inflammatory substances that are good for brain health. Snack on cucumbers, add them to a salad or simply mix with tomatoes, olive oil And balsamic vinegar for maximum a simple dish. This is very convenient way add liquid to your diet! 
Zucchini
This is a great vegetable that even fits as an alternative to pasta without the extra carbs and calories. It's ninety-five percent water, so it's a very good moisturizing product. At the same time, zucchini can even be added to pastries. Just experiment and find the recipe that works best for you. 
Watermelon
Watermelon is great for helping you stay hydrated on a hot day. It is ninety-two percent water, plus it's full of nutrients like vitamins A, B6, C, as well as lycopene and antioxidants. You can use watermelon both to flavor water and to prepare a healthy fruit ice. When watermelon season begins, be sure to take this opportunity to fill your body with fluid! 
Celery
Celery is great for fighting cancer, and it contains ninety-five percent water. Luteolin, a substance found in celery, can stop growth cancer cells especially in the pancreas. Apigenin can stop the development of cancer cells in the breast. In addition, celery is rich in fiber, which provides a long feeling of satiety. 
Carrot
Carrots are 90% water and are high in fiber. Carrots are very good for the eyes. Increase its amount in your diet by chopping carrots and adding them to your salad. You can also snack on carrots with hummus or guacamole. There are a lot of options, and any of them will be useful to you. 
Radish
This vegetable is ninety-five percent water. You can safely snack on radishes! This product helps to cool the body: its sharpness helps to cope with excessive heat. In addition, radishes are a source of vitamin C, phosphorus and zinc, key minerals and antioxidants that protect cells and nourish tissues. Add such a component to salads, sandwiches, look for new recipes - your body will only thank you. 
Kiwi
Usually everyone knows only that oranges are excellent source vitamin C. At the same time, there is more of this vitamin in kiwi, besides, they are eighty-five percent water and contain as much potassium as medium banana. Kiwi has a low glycemic index, which allows you to get a slow rise in blood sugar levels. These tropical fruits will delight the sweet tooth and perfectly complement the salad. Vitamin C is important to combine with zinc to strengthen the immune system during the season of colds. 
Peaches
These fruits contain eighty-eight percent liquid, and they are incredibly tasty. They are able to prevent related overweight diseases such as diabetes and cardiovascular disease. Eat more peaches. With such a sweet fruit in the diet of harmful desserts, you don’t even want to! 
Potato
Potatoes contain eighty percent water, and besides, this good source potassium, a key mineral for healthy blood pressure. Red-skinned varieties contain more water. Bake potatoes with their skins on to keep the potassium inside, then eat them with broccoli, cheese, beans, or lean protein. This excellent dish, which benefits and guarantees satiety for a long time. 
Broccoli
This is one of the most healthy vegetables. Broccoli contains phytonutrients, antioxidants, fiber, vitamins, minerals, and is ninety-one percent water. Try to add this component more often different dishes: salads, cream soups, omelets. It will bring you invaluable benefit and very pleasant taste. 
cantaloupe melon
This good component for fruit salad, but just with cheese, melon is also delicious to eat. It's ninety percent liquid, plus beta-carotene and vitamin C. It's delicious and very healthy, so try not to forget about it. this product when formulating your diet. 
Eggplant
Eggplants come in a variety of colors and contain about eighty-nine percent water. Be sure to enable this low-calorie product into your diet. Eggplant is a source of copper, B vitamins, magnesium, vitamin K and potassium. All these nutrients support a healthy metabolism, strengthen the immune system and cardiovascular system. Don't fry the eggplant, bake it or use it as an alternative to meat. You can even use eggplant to make pizza - use thin slices instead of the base from the test. 
Jicama
This rare vegetable has a crunchy texture and sweet taste. Jicama is ninety percent water and contains a lot of vitamin C, iron and potassium. Selling on the streets of Mexico fruit salads with jicama, seasoned with lime juice and chili powder. It's delicious, but also amazingly healthy. 
tomatoes
Tomatoes are almost ninety-five percent water, making them one of the most hydrating options. In addition, they are very rich in nutrients. They are a rich source of lycopene, a substance known to fight cancer, and contain vitamins A and C. You can even grill tomatoes with olive oil. They are suitable for so many dishes, so that your body will be filled with liquid without any additional effort. 
Strawberry
These berries are natural alternative sweets. Strawberries are ninety-two percent liquid, making them the most hydrating fruit. Add strawberries to water along with mint leaves For an appetizing drink, make a salad or simply eat berries without any additions. 
Iceberg lettuce"
This salad is considered the least nutritious, but it has a lot of water. It is ninety-six percent liquid, low in calories, and has plenty of fiber and vitamins A and C. Add salad to sandwiches or rolls for a nice crunchy texture. 
Cauliflower
If you think that this product lacks flavor, you should change your mind. Cauliflower can absorb the flavors of foods that complement it in the dish, so it is great for soups and cheese dishes. At the same time, it is ninety-two percent water. In one serving, there are also three and a half grams of fiber, which also brings great benefits to the body.
Included in all food products. According to the volume it occupies total mass In many food products, water is the most significant component, and it affects many of their qualitative characteristics, especially texture and structure. The highest water content is typical for fruits and vegetables (72-95%), milk (87-90%), meat (58-74%), fish (62-84%). Much less water found in margarine, butter (15.7-32.6%), starch (14-20%), grains, flour, cereals, pasta, dried fruits, vegetables and mushrooms, nuts (10-14%), tea (8.5%). Minimal amount water is found in milk powder (4.0%), candy caramel (3.6%), table salt(3.0%), cooking oils (0.3%), vegetable oil and sugar (0.1%).
In animal and plant tissues, water is the most variable component chemical composition. For example, in potatoes, depending on the economic botanical variety, growing area, soil, climatic conditions and growing season, the amount of water ranges from 67 to 83%.
In products made from plant and animal raw materials - sugar, confectionery, cheeses, etc. - the water content is regulated by standards.
For many food products, the water content (moisture) is an important indicator of quality. Reduced or increased content water against the established norm for the product causes a deterioration in its quality. For example, a decrease in moisture in marmalade and jam worsens their texture and taste, loss of moisture fresh fruits and vegetables reduces cell turgor by 5-7%, so they become lethargic, flabby, their quality drops sharply and they quickly deteriorate.
Products with high content water is unstable during storage, as microorganisms quickly develop in them. Water contributes to the acceleration of chemical, biochemical and other processes in food products. Raw meat and fish are easily affected by bacteria, while fruits and vegetables are easily affected by mold fungi.
Products with a low water content are better preserved, flour, cereals, pasta, dried fruits and vegetables and other products are stored for a long time; at high humidity, these products quickly become moldy during storage.
However, different food products with the same moisture content are often stored differently. It was found that it matters what forms of connection water is associated with the main substances of food products. To take into account these factors, in the early 50s of the last century, a new concept appeared - water activity, denoted by a w . Water activity a w is expressed as the ratio of the water vapor pressure over a given product to the water vapor pressure over clean water at the same temperature. Water activity characterizes the state of water in food products and determines its availability for chemical, physical and biological reactions. Usually, the more water is in a bound state, the less its activity. But even bound water under certain conditions can have a certain activity.
According to water activity, food products are divided into three groups:
1. Fresh food products rich in water, in which its activity is 0.95-1.0. These include fresh vegetables, fruits, juices, milk, meat, fish, etc.;
2. Processed food products with a water activity of 0.90-0.95. These include bread, boiled sausages, ham, cottage cheese, etc.;
3. Food products with water activity up to 0.90. These include cheese butter, smoked sausages, dry fruits and vegetables, cereals, flour, jam, etc. The water activity in these products is often 0.65-0.85, and the moisture content is 15-30%.
To prevent a number of physicochemical, biochemical reactions that reduce the quality of food products during storage, their microbiological spoilage, effective tool is the reduction of water activity in food products. To do this, use drying, drying, adding various substances (salt, sugar, etc.), freezing. Low water activity hinders the development of microorganisms and physical-chemical and biochemical reactions. For each type of microorganisms there is a lower threshold of water activity, below which their development stops.
In addition to affecting the processes that occur during food storage, water activity is also important for the texture of products. The maximum water activity allowed in dry products without losing the desired properties is 0.34-0.50, depending on the product ( powdered milk, crackers). High water activity is needed for soft textured products that should not be brittle.
Food products are hygroscopic . Hygroscopicity refers to the properties of products to absorb from the surrounding atmosphere and retain water vapor. hygroscopicity depends on physical and chemical properties products, their structure, the presence of water-binding substances in them, as well as the temperature, humidity and pressure of the surrounding air .
During the storage of food products, an equilibrium moisture content is created, in which there is no absorption of moisture by products from the environment, and moisture from the products does not pass into the environment. This state occurs when the pressure of water vapor over the products is equal to the partial pressure of water vapor in the surrounding space at the same temperature of the ambient air and the product.
The equilibrium moisture content of products is dynamic, as it changes depending on external conditions - humidity, air temperature and pressure, as well as on the physicochemical properties of the product. When external conditions change, the equilibrium moisture content of the products changes, and then re-establishes itself at a new level.
When choosing food storage conditions, it is recommended to create such a relative humidity at which the products are not spoiled by microorganisms and do not reduce their quality due to drying out, wilting or too much moisture. So, when storing flour, the relative humidity of the air should be 70%, fresh potatoes and apples - 90-95, green vegetables - 100%.
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