Enzymatic Determination of Galactose and Lactose in Honey

Abstract

Even when galactose and lactose are present in extraordinarily low concentrations in honey, both sugars are important constituents of this foodstuff because they might be useful in its characterization. Lactose and galactose determination in honey is also important because of the toxic effect of both sugars on honey bees. For the first time, a modification of the Boehringer-Mannheim GmbH enzymatic method is applied to 46 floral unpasteurized honeys for analyzing these sugars accurately, specifically, and quickly, with very low detection limits. Galactose is quantified directly without previous elution. The method avoids both previous chromatographic elution of mono- and disaccharides and removal of glucose. For galactose analysis pretreatment of honey solution with 0.5 mL of Carrez I, the same quantity of Carrez II, and 4 mL of 0.1 N NaOH is necessary; after filtration, 0.100 mL is used as sample solution, and galactose dehydrogenase is employed as enzyme. For simultaneous determination of galactose and lactose, not only is the previous clarification with Carrez solutions necessary, but neutralization with 1 mL of 0.1 N NaOH and 3 mL of 0.1 N KOH is also required. After the filtration, it is necessary to use 0.050 mL as sample solution and galactose dehydrogenase and β-galactosidase as enzymes. For a microtest, 0.99 mL final volume is required. Precision (%CV < 2.40 for galactose and <2.01 for lactose) and recovery (99.9% for galactose and 100.3% for lactose) were good. The galactose content of the honeys analyzed ranged between 0.0052 and 0.0151%. The lactose content of the honeys analyzed ranged between 0.0062 and 0.0383%. Keywords: Honey; galactose; lactose; enzymatic analysis

Carbohydrate determination in honey samples by ion chromatography–mass spectrometry (HPAEC-MS)

“…The percentage of lactose was 4% in dandelion, 3% in multifloral and honeydew, and 2% in acacia and rhododendron honeys. Literature data show that lactose should be present in honeys only at very low concentration, approximately 0.01% [44]; in another previous work, lactose was monitored in honey samples by a different technique, but the authors did not provide data about the presence of this disaccharide in honey [42]. Among other carbohydrates, lactose and galactose are important compounds in honey because they might be useful for its characterization, although these sugars can be present at low concentration [44].…”

“…Arabinose, xylose, ribose, mannose, galactose, and stachyose had concentrations below the MDL in all analyzed samples. Therefore, they were not used to characterize the honey samples in this study, although some previous studies reported that some of these compounds had detectable concentrations, e.g., one study carried out on honey samples from Spain showed that galactose had concentrations ranging between 0.0052 and 0.0151% [44]. Figure 3 reports the mean concentration and standard deviation of the saccharides, which can be related to the floral origin, in the 43 honey samples (23 multifloral, 4 acacia, 4 dandelion, 8 rhododendron, and 4 honeydew).…”

Novel glucose non-interference biosensor for lactose detection based on galactose oxidase–peroxidase with and without co-immobilised β-galactosidase

“…In enzymatic methods for lactose detection, either glucose [by glucose oxidase (GOD) and peroxidase (HRP)] 2 or galactose (by galactose dehydrogenase) 3 have been detected optically after hydrolysis by b-galactosidase (GAL). An immobilisation procedure allows biological parts to be reused (enzymes, microbial cells, etc.…”

Sugar composition and sugar-related parameters of honeys from the northern Iberian Plateau

“…The main sugars of honey are fructose and glucose, whose sum, together with sucrose content, are used as quality criteria for honeys within the European Union (OJEC, 2002). Honey also contains a complex A C C E P T E D M A N U S C R I P T mixture of other mono-, di-, tri-, oligo-and polysaccharides (Val et al, 1998;Bogdanov et al, 2008). Sugars contribute to the antibacterial properties of honey and its preservation, because they provide high osmolarity and low water activity, which makes microorganism growth difficult.…”