Food analysis carbohydrates

A number of criteria could be apphed to organize this chapter, depending on the point of view by which foods are considered. In this chapter, application of HPLC to food analysis will be described considering homogeneous classes of food components lipids, carbohydrates and related substances, proteins, peptides, amino acids, biogenic amines, phenolics, vitamins, and some selected contaminants. 

For many years, and still, controlling available carbohydrate intake has been a cornerstone of diabetes management. However, in many foods available carbohydrate, measured as carbohydrate available in food analysis, is not quite the same as carbohydrate that is available in the gut in food as normally consumed. Glycemic response depends not only on the amount of potentially available carbohydrate consumed, but also on how rapidly it is digested, absorbed, and disposed of in the body, and that depends on a myriad of factors including food structure and the influence of other food components that vary in importance from food to food. 

Some basic food analytical methods such as determination of °brix, pH, titratable acidity, total proteins and total lipids are basic to food analysis and grounded in procedures which have had wide-spread acceptance for a long time. Others such as analysis of cell-wall polysaccharides, analysis of aroma volatiles, and compressive measurement of solids and semi-solids, require use of advanced chemical and physical methods and sophisticated instrumentation. In organizing the Handbook of Food Analytical Chemistry we chose to categorize on a disciplinary rather than a commodity basis. Included are chapters on water, proteins, enzymes, lipids, carbohydrates, colors, flavors texture/ rheology and bioactive food components. We have made an effort to select methods that are applicable to all commodities. However, it is impossible to address the unique and special criteria required for analysis of all commodities and all processed forms. There are several professional and trade organizations which focus on their specific commodities, e.g., cereals, wines, lipids, fisheries, and meats. Their methods manuals and professional journals should be consulted, particularly for specialized, commodity-specific analyses. 

The problems encountered are numerous. Tryptophan is highly prone to degradation in acid digestions. This is especially the case in food analysis, where samples often contain significant quantities of carbohydrates that greatly exacerbate tryptophan s degradative tendencies. Cyst(e)ine is partially oxidized during acid hydrolysis and will likely be found in several forms cystine, cysteine, cysteine sulfinic acid, and cysteic acid. Methionine can be partially lost in simi-... 

The first edition of Food Analysis by HPLC fulfilled a need because no other book was available on all major topics of food compounds for the food analyst or engineer. In this second edition, completely revised chapters on amino acids, peptides, proteins, lipids, carbohydrates, vitamins, organic acids, organic bases, toxins, additives, antibacterials, pesticide residues, brewery products, nitrosamines, and anions and cations contain the most recent information on sample cleanup, derivatization, separation, and detection. New chapters have been added on alcohols, phenolic compounds, pigments, and residues of growth promoters. 

In the same way, the energy our bodies need to keep warm, move about, and build new tissue comes from a food reserve carbohydrates, chiefly in the form of starch. (We eat other animals, too, but ultimately the chain goes back to a carbo-hydrate-eater.) In the final analysis, we get energy from food just as we do from petroleum we oxidize it to carbon dioxide and water. 

Refractive index monitors are used in food analysis, for detecting carbohydrates, alcohols, and other substances with weak or no UV absorption. 

The quality assessment of food and fodder products requires analysis of protein, carbohydrates and fat. The enzyme electrode-based analyzers originally developed for clinical chemistry have found only limited application in food analysis because they are only suitable for the determination of one parameter, mostly glucose or a disaccharide. The increasing concern for food quality require new types of biosensors allowing residual and hygiene control and on-line measurement of age and freshness (Tschannen, 1988). 

A number of very good reviews on food analysis can be found in the literature [7-12]. Table 3 presents a very limited representation of the kind of work involved in a food laboratory. All basic constituents of foodstuffs - proteins, lipids, carbohydrates and vitamins - are amenable to liquid chromatography. Various types of columns and detectors used for those analysis demonstrate the versatility of the technique. Almost any type of food matrix can be extracted in order to identify and quantitate trace amounts of analytes. 

High-performance LC (HPLC) is the technique used most frequently in food analysis for measuring carbohydrates, vitamins, additives (sweeteners, antioxidants, colorants, preservatives, etc.), mycotoxins, amino acids, proteins, tryglicerides in fats and oils, lipids, chiral compounds and pigments, among others (Table 1). Some of these applications will be discussed in this article. 

Amperometry is probably one of the most common electroanalytical techniques used in food analysis and there are numerous examples in the literature. Among others, it is worth mentioning analysis of cholesterol [72], vitamins [73, 74], carbohydrates [75, 76], antioxidants [4, 77-79], pesticides [80, 81], and toxins [82]. It is also important to point out that, although not discussed in this chapter, the same instrumental configuration used in amperometry can be used for the development of amperometric biosensors [83-86], electrochemical ELISA assays [87-89], and electrochemical tongues [90,91]. 

Nutrient analysis of stabilized rice bran and its derivatives indicates that it is a good source of protein, dietary fiber and carbohydrates, in addition to several valuable phytonutrients, antioxidants, vitamins and minerals (Table 17.1). SRB and its water-soluble and water-insoluble derivatives contain all the nutrients at different levels. They are gluten and lactose free and do not give rise to any food allergy. 

Low, N. H., Brisbane, T., Bigam, G., and Spoms, P. (1988). Carbohydrate analysis of western Canadian honeys and their nectar sources to determine the origin of honey oligosaccharides. /. Agric. Food Chem. 36, 953-957. 

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