Carbohydrates caloric value

It would seem that normally the oxidation of ketone bodies would proceed largely to completion in the liver by the ketolytic mechanism. Whenever the supply of carbohydrates here is sufficiently reduced, appreciable amounts of ketones then escape oxidation and pass into the blood. When the concentration of ketones becomes sufficiently elevated, a ketonuria occurs and also some ketones will be utilized by the tissues. Such a theory would largely limit the ketolysis mechanism to the liver. It would explain the specificity of the sugars in preventing ketonuria and the discrepancy between the amount of D-glucose required to prevent ketosis and the caloric value of the fat spared. It is further supported by the demonstration that the liver is capable of exhibiting ketolysis. 

It is recommended that about half of the energy intake should be in the form of carbohydrates, a third at most in the form of fat, and the rest as protein. The fact that alcoholic beverages can make a major contribution to daily energy intake is often overlooked. Ethanol has a caloric value of about 30 kj g (see p. 320). 

Sweetener/ carbohydrate Relative sweetness (Sucrose =1) Solubility (g/100 g water at 20°C) Insulin- dependent metabolism Caloric value (kcal/g) Approval for use in soft drinks Dietary fibre approval ... 

Foods differ in their energy value, which is usually expressed in kilocalories or kilojoules, with proteins and carbohydrates having less caloric value than fats (lipids). Fats... 

Food is "burned" in the body to yield H20, C02, and energy, just as natural gas or coal is burned in a furnace to yield the same products. In fact, the "caloric value" of a food is just the heat of reaction, AH0, for complete combustion of the food (minus a small correction factor). The value is the same whether the food is burned in the body or in a laboratory calorimeter. One gram of protein releases 17 kj (4 kcal), 1 g of carbohydrate releases 17 kj, and 1 g of fat releases 38 kj. As shown in Table 8.4, which gives the caloric value of some common foods, data are usually given in Calories (note the capital C), where 1 Cal = 1000 cal = 1 kcal = 4.184 kj. 

The numbers quoted in Table 8.4 are not very precise, and different reference sources often give different values. Part of the problem is that the source and variety of the food can cause large differences—an "apple," for instance, may be any one of over a hundred varieties and may come from practically any country on Earth. Perhaps even more important is that many foods—carbohydrates such as bread, in particular—contain a large but variable amount of water, which increases the mass of the food but adds no caloric value. 

Polyols are unique among simple carbohydrates in their low ability to be fermented. This characteristic enables them to impart sweetness to foods while exhibiting lower caloric values than other carbohydrates and reducing the formation of dental caries. Polyols are used in a variety of applications in foods, confections, pharmaceuticals and industrial uses. Rising demand for low- and reduced-calorie foods and confections that contribute to a reduction in dental caries has contributed to the growth of these starch-derived products. 

Fats and carbohydrates are the principal sources of energy in foods. Pure fat has a caloric value (heat of combustion) of 4080 kcal per pound, and pure carbohydrate (sugar) a caloric value of about 1860 kcal per pound. The caloric values of foods are obtained by use of a bomb calorimeter, just as was described above for fuels. The third main constituent of food, protein, is needed primarily for growth and for the repair of tissues. About 50 g of protein is the daily requirement for an adult of average size. Usually about twice this amount of protein is ingested. Tliis amount, 100 g, has a caloric value of only about 400 kcal, the heat of combustion of protein being about 2000 kcal per pound. Accordingly fat and carbohydrate must provide about 2600 kcal of the 3000 kcal required daily. 

Edible fats and oils (lipids) are derived from plant, animal, and marine sources. Fats and oils differ in that fats are solids at normal room temperature whereas oils are liquids under similar conditions. Lipids are recognized as essential nutrients in both human and animal diets. They provide the most concentrated source of energy of any foods. The caloric value of lipids (9 kcal/g) exceeds twice that of proteins and carbohydrates (4 kcal/g). Lipids not only contribute to flavor, color, odor, and texture of foods, but also confer a feeling of satiety after eating. Lipids also act as carriers of fat-soluble vitamins, supply essential fatty acids, and increase the palatability of foods. Dietary fats are often categorized as visible or invisible ... 

Lipids comprise one of the three broad classifications into which nourishing substances can be broken. Lipids, proteins, and carbohydrates are the three very general classifications. Fiber may be filling but is not called nourishment. Lipids are rich in energy, supplying twice the caloric value per unit weight than carbohy-... 

The date fruit consists of 70 percent carbohydrates (mostly sugars), making it one of the most calorie-rich, high-nutrient fruits available. With the present uncertainty in the world food supply and the expected increase in demand from food production countries, the date could be a premium source of high nutritional and caloric value, and it preserves easily for shipping and storage. 

The emulsifiers have essentially the same caloric value as fats. Thus, there is no advantage to use them as fat replacers. Lipid-based replacers (also referred to as synthetic fat substitutes) are non-caloric, but the majority of them are not approved for food use at this time (Tab. 5.5). Carbohydrate-based fat replacers include starches and their derivatives (Tab. 5.6) as well as non-starch hydrocolloids (Tab. 5.7). A selection of protein based and mixed-blend replacers is given in Tab. 5.8 and 5.9, respectively. 

Many carbohydrate-based fat substitutes are mixtures of sucrose esters formed by chemical transesterification or interesterification of sucrose with one to eight FAs. The class with six to eight FAs are called sucrose FA polyesters. These molecules are too large to be broken down by intestinal lipase enzymes and, for that reason, do not show any caloric value (Voragen, 1998). 

Physiological Properties. Physiologically, dietary caloric value is entirely typical of all edible carbohydrates. No nutritive factor other than caloric value is to be expected unless specifically added. 

The caloric value of a food is applicable in humans only if our cells have enzymes that can oxidize that fuel by transferring electrons from the fuel to NAD+, NADP+, or FAD. When we burn wood in a fireplace, electrons are transferred from cellulose and other carbohydrates to O2, releasing energy as heat. However, wood has no caloric content for humans we cannot digest it and convert cellulose to a form that can be oxidized by our enzymes. Cholesterol, although a lipid, also has no caloric value for us because we cannot oxidize the carbons in its complex ring structure in reactions that generate NADH, FAD(2H), or NADPH. 

The energy content of foodstuffs varies. The approximate caloric content of generic carbohydrates, fats, and proteins are listed in Table 23-1. These values are based on a varied diet, i.e., all components are present. Recall that humans cannot synthesize glucose from fat. In the absence of carbohydrates, therefore, fat metabolism becomes inefficient, and the caloric value of fat decreases. 

Hazelnut contains all major macronutrients fat, carbohydrate, and protein. Table 12.1 shows the proximate composition and caloric value of various hazelnut varieties grown in different countries [6,10,11,13,14]. Based on the date given in Table 12.1, fat is the predominant component (58.40-64.10g/100g), followed by carbohydrate (15.50-17.61 g/lOOg), protein (10.86-16.30g/100g), moisture (3.90-5.40g/lOOg), and ash (2.20-2.69g/lOOg). These values are comparable with those published in the literature [6,9,15-18]. Several factors have been reported to affect the proximate composition of hazelnut [3,6,9,13,16,17,19,20]. 

For example, if a steak is 49% water, 15% protein, 0% carbohydrate, 36% fat, and 0.7% minerals, then 3.5 ounces of steak (about 100 g) would provide about 384 kcal, or 384 food Gal. Note that a food Calorie (Cal) is indicated with a capital G and is actually equivalent to 1000 calories (cal) or 1 kilocalorie (kcal). The caloric values of most foods are found as illustrated in the margin, and these are the values that are hsted in diet books and on food labels. (Some representative values are given in Table 16.2.)... 

The calorific (caloric) value of beer is due to ethanol, residual carbohydrate, and protein and can be calculated from the equation ... 

Another disadvantage is supposed to be the caloric value that diabetics have to take into account. However, with the increased use of blood glucose monitors and relatively simple insulin delivery devices it has become easier to match the carbohydrate intake to the blood sugar level, especially for patients with type I diabetes. Apart from that the contribution of sugar through medicines is small and it is actually not necessary to develop special sugar-free medicines for diabetics. 

In formulation of diets to meet energy requirements, proteins and carbohydrates are considered to yield 4 cal. per gram, and fats, 9 cal. per gram. The specific dynamic action of foodstuffs must also be considered and is usually calculated as 6 % of the total caloric value of the food over a 24-hr. period.2 ... 

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