High Performance Liquid Chromatography (hplc) Study of Sugar Composition in Some Kinds of Natural Honey and Winter Stores Processed by Bees from Starch Syrup

Sugar composition was determined in three groups of products: starch (maltose) syrup produced in Poland from wheat starch (for several years beekeepers have been trying to use it as bee food), winter store made from the syrup by bees and honey. Winter stores were analyzed in three subgroups: subgroup 1 – material collected from honeycombs of bee colonies two months after the syrup was fed to the bees in autumn (end of October of 2004); subgroup 2 – material collected from the same bee colonies following seven months of feeding (spring of 2005); subgroup 3 – samples of winter stores which crystallized in the combs collected most of the time in early spring of 2006 (sent in by beekeepers from different regions of Poland from the season of 2005/2006). Sugar content assays were made by HPLC with a refractometer detector according to Bogdanov et al. (1997). The following sugars were assayed and compared: glucose, fructose, sucrose, maltose, isomaltose, turanose and trehalose. Significant differences were found for the contents of individual sugars in the stores made from syrup vs. those in the honey. Routine HPLC assays of sugars can be helpful in the identification of products made by bees from maltose syrups. The main distinguisher for those products was fructose content (lower than that in honey by 32%), high maltose content (over 5%) and low fructose to glucose (F/G) ratio (0.76 when averaged across subgroups) whereas in honey samples it was 1.18 on average. The lowest values of that parameter were found for rape honey averaging 0.98%. Another problem explained by the study was that of the crystallization of stores processed from maltose syrup following their depositing in the combs as winter storage. The crystallization occurred only in part of the apiaries that were fed maltose syrup in the season of 2005/2006. It was found in that group of samples that fructose content was significantly lower and that of glucose significantly higher than in the remaining ones (non-crystallized or partly crystallized). According to Ohe von der and Schönberger (2000) the critical point for at which a solution becomes saturated with glucose is 32 g/100 g and once that concentration is exceeded crystallization occurs. In the examined samples the concentration of glucose averaged as much as 38.98%. It caused the sugar to crystallize already in the comb cells. In the apiaries in which crystallization of maltose syrup derived stores occurred there were conditions which favoured enzymatic hydrolysis of complex sugars to simple ones. Of particular importance here is the breakdown of maltose which occurred in maltose syrup at a relatively high concentration of ca. 20%. The process caused glucose concentration to rise rapidly whereas accidentally more favourable weather conditions, earlier feeding of bees to prepare them for wintering, exceptionally strong colonies and other factors coincided to accelerate enzymatic hydrolysis of complex sugars thereby causing rapid crystallization of the stores. The bees processed the fed syrup so thoroughly that it led to excessive glucose concentration and consequently, to glucose crystallization in comb cells.