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An Overview of Coffee Carbohydrates

Meenakshi, Arya (2005) An Overview of Coffee Carbohydrates. Masters thesis, University of Mysore.

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Abstract

This Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page.

Item Type: Thesis (Masters)
Additional Information: <p align="justify">In many parts of world, coffee is one of the most popular beverages. Coffee contains virtually no food value in itself and it is consumed for its refreshing and stimulating properties. Different manufacturers favour various coffee blends and procure these beans from the countries producing the required coffee types. Coffee processing involves various stages which are roasting , grinding and extraction to obtain soluble coffee beverage / powder. Carbohydrates are the major constituents of coffee beans and serve various functions like, binding of aroma, stabilization of foam, formation of sedimentation and increase in viscosity of the extract. The monosaccharide content is relatively low in green coffee. The principal low molecular weight carbohydrate is disaccharide viz., sucrose. There is no evidence of other simple oligosaccharides such as ‘flatulent sugars’raffinose or stachyose. Polysaccharide fraction from green coffee bean is dominated by three polymers viz., 1. Arabinogalactan, 2. Mannan (and / or galactomannan) and 3. Cellulose. Other monosaccharides are xylose and rhamnose. Low molecular weight carbohydrates in roasted coffee are sucrose, inositol phosphates and attractyloglycosides. Sucrose in coffee beans is rapidly degraded on roasting. Early reaction products are the inherent sugars viz., fructose and glucose, as well as, 1,6 anhydroglucose, arabinose and erythritol. Most of the cell wall macrostructure survives conventional roasting conditions. However, selective degradation of the polysaccharide fraction on roasting is reported. Roasting improves the extractability of the coffee polysaccharides. In the recent years there has been a large amount of activity in the area of sugar profiling of commercial soluble coffee products. In commercial soluble coffee processes, the elevated temperature lead to hydrolysis of the polysaccharide fraction reflected in the increased levels of the constituent monosaccharides viz., arabinose, galactose and mannose. Although the total extractable content of carbohydrate is similar, for light, medium and dark roasts, the carbohydrate composition shows significant differences both in terms of type and size distribution. Substantial hydrolysis of the polysaccharide fraction occurs during extraction, but studies have indicated the presence of polymeric carbohydrate in coffee extracts obtained under commercial conditions. During roasting, the characteristic aroma, flavour and colour of the coffee bean are generated and polysaccharide content is reduced due to degradation to mono and oligo saccharides and became more extractable. The increase in ease of extractability is in part also due to changes in the microstructure of the bean, as the beans increase in volume and large micro pores appear in the cell wall. Various methods that can be employed to extract the carbohydrate from roasted and ground coffee are: Sequential extraction, extraction of arabinogalactans, acid hydrolysis,hot water extraction, enzymatic extraction,enzymatic saccharification and quantitative determination of the coffee carbohydrates. Besides improving the organoleptic quality of the coffee beverage, carbohydrates also possess various biological activities. They are not hydrolyzed by mammalian enzymes and have the potential to function as dietary fibre thus can lower colon cancer risk. Regardless of the mannoligosaccharides molecular weight, all mannoligosaccharides are used by Bifidobactrium addescentis, Lactobacillus acidophilus and Lactobacillus gasseri, while the harmful bacteria such as Clostridium perifringens and Escerichia coli that produce mutageniuc substances can not use mannoligosaccharides. Hence, it can be concluded that mannoligosaccharides have a potential to promote the improvement of healthful human intestinal micro flora as prebiotics. Besides their sheer mass, a variety of evidences testify to the important contribution that the polysaccharide content makes to the character of final brew. Although number of chemical and enzymatic methods have been devised to isolate and quantify the carbohydrates from roasted and ground coffee, till date hot water extraction is the only method which can be accepted as a most feasible process for extraction of coffee carbohydrates so there is a wide scope of further research for the efficient and economical technology for extraction of carbohydrate from coffee.</p>
Uncontrolled Keywords: coffee carbohydrates coffee
Subjects: 500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 13 Carbohydrate Chemistry
600 Technology > 07 Beverage Technology > 04 Coffee
Divisions: Human Resource Development
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 26 Feb 2007
Last Modified: 28 Dec 2011 09:26
URI: http://ir.cftri.com/id/eprint/403

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