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| Author(s): |
Paula Aparecida Delgado
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Química |
| Defense date: | 2008-09-05 |
| Examining board members: |
Telma Teixeira Franco;
Eliana Setsuko Kamimura;
Francisco Maugeri Filho;
Helia Harumi Sato;
Marcelo Caldeira Viegas;
Matti Sika aho
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| Advisor: | Telma Teixeira Franco |
| Abstract | |
Polysaccharides are the main components of green, roasted and soluble coffee, and they are mainly galactomannans and arabinogalactans. An important aspect about these polysaccharides is the insolubility, possibly one of the reasons for the sediments formation in the production of instant coffee, reducing the yield of the process. Thus, the aim of this work was to investigate the reduction of sediments in coffee extract by the action of enzymes. Several commercial preparations of pectinases were selected and their different activities were determined. Rohapect B1L presented the highest mannanase activity. Most of the commercial pectinases assayed presented other enzyme activities, like mannanase, endoglucanase, xylanase, besides the activity stated by the manufacturers. Soluble and insoluble fractions from coffee extract and sediment were prepared and their chemical composition determined. The main components of extract and its insoluble fraction were carbohydrates and proteins, while the insoluble fraction of sediment presented also a significant amount of lignin. Based on the carbohydrate analysis, galactose, arabinose and mannose were the main monosaccharides obtained after acid hydrolysis, confirming the presence of galactomannans and arabinogalactans. Galactomannan with low degree of branching was found to be the main polysaccharide of the insoluble fractions. Biopectinase CCM, Rohapect B1L, Pectinase 444L and Galactomannanase ACH were found to be themost effective enzyme preparations on the sediment reduction of coffee extract, being Rohapect B1L and Galactomannanase ACH the more viable ones, which optimumconcentrations were 0.3 and 0.1 mgprotein/gsubstrate, respectively. The average molecular weight of the coffee extract components was 18 kDa, which decreased 6.6% after hydrolysis with Rohapect B1L. The main sugar released by this enzyme preparation was mannose, suggesting its action on coffee mannans, due to the high activity of mannanase. The extracts hydrolyzed by Rohapect B1L and Galactomannanase ACH were evaluated for the sensory quality. Trained panelists indicated a small to moderate difference between the hydrolyzed extracts and the control; however, the enzymatic treatment did not alter the consumers¿ acceptance of the coffee extract. The results showed good perspectives for the use of enzymes in reducing sediments in coffee extracts (AU) | |