Changes in the contents of mono-, di- and oligosaccharides in leek plants stored in cold room

摘要

The aim of this work is to present the results of the analysis of composition of mono-, di- and oligosaccharides, including the content of fructooligosaccharides as well as rafinose, stachyose in pseudo stalk of leek plants of the following cultivars: Shelton F1, Belton F1 and Parton F1. Leek plants were stored in cold room at the temperature 0 °C and relative humidity around 98% in the period from December to May. Fructose, glucose, saccharose, fructooligosaccharides (FOS) as well as α-galactosides were determined with the HPLC method with the application of water-alcohol extracts. It was shown that some of the studied parameters have changed during storage, i.e., the glucose content increased from 4.4 ± 0.3 to 16.2 ± 1.6, fructose from 4.7 ± 0.2 to 23.8 ± 0.4, saccharose from 5.1 ± 0.7 to 18.7 ± 0.1, depending on the cultivar and the storage period. The largest increase in the content of fructose and glucose took place between 60th and 90th day of storage which testifies to intensive hydrolysis of fructans. Leek cv. Parton F1 was characterised by the largest content of fructans and the lowest susceptibility to hydrolysis. The amount of kestose, nystose and rafinose after the period of storage changed from 0.3 ± 0.0 to 0.9 ± 0.2, 0.5 ± 0.1 to 1.8 ± 0.1, 0.8 ± 0.1 to 1.8 ± 0.2 g/100 g of dry mass, respectively. The content of stachyose, in turn, remained at a constant level and amounts to around 0.5 g/100 g of dry mass. Leek plants kept in typical refrigeration conditions are characterised by good durability and constitute a valuable merchandise. However, due to ongoing hydrolysis processes, the content of prebiotic substances decreased what lowered the health-promoting value.