Determination of carbohydrates in animal foods as seven fractions

Authors

• Maija-Liisa Salo Department of Animal Nutrition and Husbandry, University of Helsinki

DOI: https://doi.org/10.23986/afsci.71561

Abstract

An analysis system is described by means of which the carbohydrates of plant materials are successively dissolved, hydrolyzed, and determined as reducing sugars. The uronides are determined on a separate sample. In this manner 7 groups are obtained: 1) monosaccharides, 2) di-, and oligosaccharides. 3) fructosan, 4) starch. 5) hemicellulose, 6) cellulose, 7) uronides. The final hydrolysis residue from the carbohydrate hydrolysis is considered as lignin. Furthermore, crude fat, crude protein, ash, and in cold water soluble N-free non-carbohydrate organic matter are determined. The total of the results of the analyses appears to be approximately 100 %. In an alternative system used by the author, mono-, di-, and oligosaccharides and fructosan are determined as a group. The results are compared with those obtained by fractionation. The sugar solutions have been purified and neutralised with ion-exchange resins using the bath-method. Duolite A-7 and Duolite C-3 have been found to be suitable for these purposes in experiments which were made with pure solutions of individual sugars. The purity of different fractions of carbohydrates has been checked by paper chromatography. Also the proportions of individual monosaccharides in a hemicellulose fraction for a more exact calculation of their value for hemicellulose were estimated by chromatography.