Carbohydrate energy value

Energy values of food can be estimated on the basis of the content of carbohydrate, protein, and fat ... 

The regulations prescribe the energy values to be used as in Table 3. There are agreed values for some other materials. The synthetic dextrose polymer poly dextrose is accepted to be only 1 kcal g 1 (or 4 kJ g 1) even though it would otherwise fall within the definition of a carbohydrate. The accepted value for gum acacia, a polysaccharide obtained from trees of the species Acacia Senegal and closely related species, is 2 kcal g 1 (or 8 kJ g-1). 

Potatoes have been valued around the world for centuries because they are an easily cultivated, easily prepared and readily assimilated source of carbohydrate energy. The ease with which potatoes are digested has, however, become a double-edged sword, as the interrelated epidemics of metabolic syndrome and type 2 diabetes become global crises linked to rising obesity. At the same time as carbohydrates have been blamed for obesity, glucose intolerance has become recognized as a core feature of the metabolic syndrome and type 2 diabetes (Seidell, 2000). 

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... 

General constituents and approximate energy values of common foods are given below. Apply Access to design a database such that the information can be retrieved according to sources of macronutrients for food types (e.g., protein sources or carbohydrate sources for cereal, fish, fruit, dairy, meat/poultry, vegetable). 

Baobab seed kernels have an energy value of 1803 kJ/100 g (Arnold et al, 1985, cited in (11)). Arnold et al, cited in (11), provided data on chemical composition moisture 8.1%, protein 33.7%, fat 30.6%, carbohydrates 4.8%, fibre 16.9% and ash 5.9%. However, higher levels of carbohydrates have been recorded (Palmer and Pitman, 1972, cited in (11)). According to (55), the seed contains relatively high amounts of protein, crude fat, and crude fibre, and low levels of carbohydrates. The baobab seeds have been subjected to extensive research, a the proximate analysis of the seeds are provided (Table VI). 

According to Becker, 1983, (2, 6), cited in (11), the leaves contain (expressed on dry weight basis) 13-15% protein, 60-70% carbohydrate, 4-10% fat and around 11% fibre and 16% ash (Table Xll). Energy value varies between 1180-1900 kJ/lOOg of which 80% is metabolizable energy. 

Let s take a closer look at the fast food dinner described in the chapter introduction. Our food is a mixture of many different kinds of substances, but the energy we need to run our bodies comes from three of them digestible carbohydrates (the source of 40%-50% of our energy), protein (11%-14%), and fat (the rest). Table 17.2 shows typical mass and energy values for a burger, a serving of fries, and a milkshake. In order to understand what happens to these substances when we eat them, you need to know a little bit more about their composition. 

There is, however, yet one more layer to the comparison as we have discussed, fat is hydrophobic. In consequence, the fat stores in our bodies are indeed almost pure fat, containing very little water. Glycogen, the carbohydrate store, is hydrophilic and therefore will be highly hydrated in the cell, and consequently much heavier than pure, dry carbohydrate. Thus, in terms of real energy value per unit weight of stored material that we carry around with us, fat wins hands down. 

Fat is needed in human nutrition for growth and replacement of tissues, for certain lipid secretions, and as a source of energy. The optimal level of fat in the diet is not known, and since fat may be formed from carbohydrate or protein, no definite requirement can be formulated. Fat increases the palatability of the diet and also reduces the bulk, since the energy value of fat is more than twice that of an equivalent amount of protein or carbohydrate. Dietary fat also acts as a carrier for the fat-soluble vitamins. 

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