The catalytic effect of honey on formation of reducing sugars during sucrose hydrolysis

Abstract

In commercial apiculture, beekepers usually remove honey from hives and replenish food reserves with sugar syrup. When honeybees use sugar syrup (sucrose solution), they break down sucrose into glucose and fructose. These processes exhaust and weaken bees. In order to prevent bee exhaustion resulting from this processing, bees should preferably be supplied with ready made food before winter, i.e., with syrup in which sucrose has already been inverted. Feeding with inverted syrups is the most popular way of honeybee feeding. Beekeepers usually prepare inverted syrups by adding a weak organic acid (citric, oxalic, acetic or lactic acid) to sucrose solution at elevated temperatures. Inverted syrup production under uncontrolled pH, temperature and time conditions can cause the formation of 5-hydroxymethyl-2-furaldehyde (HMF), a compound harmful to bees. High quality inverted syrup can be obtained through the hydrolytic decomposition of sucrose by the enzyme invertase. Due to its invertase content, honey can be used as a biocatalyst for sucrose inversion. Invertase activity depends on the type, method and time of honey storage. This study evaluates the catalytic effect of acacia honey on formation of reducing sugars during hydrolysis of 50 wt.% sucrose solution. The ratio of reducing sugars and sucrose at 40°C, after 5 days of hydrolysis at a concentration of honey and 10 wt.% was 0.30 g reducing sugars/g of sucrose. The highest content of reducing sugars was achieved at a temperature of 35°C, after 48 h of invertion. In all samples of hydrolysates obtained at different temperatures (35–65°C), HMF was detected at concentrations of less than 4.32 mg kg–1. A high degree of negative correlation (coefficient of linearity –0.94) was established between parameters of volumetric and polarimetric measurements during the hydrolysis of sucrose. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 46010]

Keywords

• honey as biocatalyst
• sucrose hydrolysis
• reducing sugars
• HMF