Carbohydrate in food

Glucose is the most important carbohydrate in mammalian biochemistry because nearly all carbohydrate in food is converted to glucose for metabohsm. 

Femia, R. E. and Weinberger, R., Determination of reducing and non-reducing carbohydrates in food products by liquid chromatography with post-column catalytic hydrolysis and derivatization comparison with refractive index detection, /. Chromatogr., 402, 127, 1987. 

Southgate DTA. Determination of carbohydrates in foods. 2.—Unavailable carbohydrates. J. Sci. Food Agric. 1969 20 331-335. 

Humans lack enzymes to hydrolyse cellulose, and some odier carbohydrates in food. However, bacteria in the intestine can hydrolyse and ferment some of this carbohydrate to produce short-chain fatty acids, which are used by the colon and the liver. It is estimated that for each gram of unavailable carbohydrate in the diet, 8.4 kJ of energy is made available in this way, although this is influenced by factors such as ripeness of fruit or the way leguminous seeds are cooked. Nonetheless, these effects will be small and can be ignored unless the amount of such carbohydrate is high or very accurate results are required. (The subject of unavailable carbohydrate and fibre in the diet is discussed in Chapters 4, 6 and 15). 

Table 19.4 reports some applications concerning HPLC analysis of carbohydrates in food samples. 

The glycemic index was, therefore, introduced as an adjunct to available carbohydrate values in diabetes management, to indicate the glycemic potency of available carbohydrate in foods relative to glucose (Jenkins et al., 1981). In recent years GI has developed its own momentum, helped by vigorous promotion, and despite continued discussion about the value it adds to... 

These are some examples of the use of i.r. spectra in the analysis and identification of carbohydrates in foods and natural products. Very often, these spectroscopic techniques are complementary to others, such as the study of aldobiouronic acids obtained by hydrolysis of peach-gum polysaccharides by their optical rotations and their i.r. spectra.100 However, the i.r. results appear to be sufficiently reliable to be used in the detection of traces of fructose and glucose, and to determine the d.e. (dextrose equivalent) of corn syrups, as well as the quantitative carbohydrate content in different products.101... 

The reader is directed to Ref. 5, which makes an interesting comparison between HPLC and other analytical methodologies for the determination of carbohydrates in foods. Additionally, notable progress has been made in the application of high-performance capillary electrophoresis (HPCE) in this field (8-11). However, given the scope of this chapter, we will focus on the advantages and drawbacks of other chromatographic techniques versus HPLC. 

There is no ideal HPLC system for the analysis of carbohydrates in foods, but of the techniques offering different and complementary selectivities, each has its own advantages and drawbacks. The characteristics of the principal systems that, at present, are most widely used are summarized in Table 5. Additionally, the reader is directed to the recent review by Churms (4), in which the performance of several HPLC systems is compared with respect to their capacity factors for sugars and polyols. 

Complex Carbohydrates in Foods, edited by Susan Sungsoo Cho, Leon Prosky, and Mark Dreher... 

Hizukuri S, Abe J, Hanashiro I. In Eliasson A-C, ed. Carbohydrates in Foods. 2nd edn. Boca Raton, FL CRC Press, Taylor and Francis Group 2006 [Chapter 9]. 

Autio, K. (1996). Functional aspects of cereal cell wall polysaccharides. In Carbohydrates in Food, Eliasson, A. (Ed.). Dekker, New York. 

Hizukuri, S. 1995. Starch Analytical aspects. In Carbohydrates in Food (A. C. Eliason, ed.), pp. 347-429. Marcel Dekker, New York. 

One of the most common hydrolysis reactions is that required to convert polysaccharides into monosaccharides prior to the determination of total carbohydrates in food and environmental samples. The use of highly acid media (e.g. 12 M sulphuric acid) and elevated temperatures ( 100°C) for 20 min produced partial oxidation of carbohydrates [80]. Using room temperature to avoid oxidation resulted in incomplete hydrolysis [81], and so did lowering the concentration of sulphuric acid to 0.5 M while keeping the temperature at 100°C for 8 h [82-84]. One of the most accurate ways of determining total carbohydrates is by using 1 M HCI at 100°C for 20 h [85,86]. 

Hizukuri S. Starch analytical aspects. In Carbohydrates in Food. 

Carbohydrates in food are important sonrces of energy. Starch, found in plant-derived food such as pasta, consists of chains of linked glucose molecules. These chains are broken down into individual glucose molecules for eventual use in generation of ATP and building blocks for other molecules. [(Left) Superstock.]... 

Ehasson AC, Gudmundsson M (1996) In Elias-son AC (ed) Carbohydrates in Food. Marcel Dekker, New York, pp 431-503... 

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