On the breakdown of sugars during the drying of plant samples and their subsequent dry storage

Authors

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

DOI: https://doi.org/10.23986/afsci.71637

Abstract

In the present studies various drying procedures were investigated and compared to freeze-drying. The persistence of sugars in some of the dried samples was also investigated. In addition, the effect of some organic acids or their salts on fructose during heating was investigated. The following results were obtained: A drying temperature exceeding 40° caused sugar losses at least in some of the plant materials. Brassica species were found to be the most sensitive to heat. The sugar content remained practically the same in vacuum drying at 40° as in freezedrying. Drying at 40° must be carried out in the absence of oxygen. During vacuum drying at 70°, oxalic, citric and malic acids – even in concentrations of only 1 % –produced a considerable decrease in the reducing activity of fructose; oxalic acid had the same effect even at 40°. The dry matter loss was not so serious. When grass samples, vacuum dried at 70°, were subsequently kept at room temperature, and when similar samples, freeze-dried, were kept at about —8°, their sugar contents after 4 months of storage were the same as immediately after drying.