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Carbohydrates
Honey is a supersaturated sugar solution with approximately 17% water. Fructose is the predominant sugar, with concentrations ranging from 36-50%, followed by glucose (28–36%). Carbohydrate composition and content of honey is variable and is dependant on the floral source of the honey. The carbohydrate composition of honey has been extensively studied using techniques including gas chromatography and high performance liquid chromatography. It has, however, been difficult to account for all carbohydrates in honey because of the lack of commercial standards and the low amounts of some of the compounds in honey. Disaccharides, trisaccharides, tetrasaccharides, pentasaccharides, hexasaccharides and other oligosaccharides are present in much smaller quantities than fructose and glucose.
Morales reported that 90% of the carbohydrates in honey are the monosacccharides glucose and fructose, and that the remaining carbohydrates comprise some 16 disaccarides and 8-12 trisaccharides. Darcy reported that the disaccharides in honey include sucrose, maltose, isomaltose, nigerose, turanose, maltulose, leucrose, kojibiose, neotrehalase, gentiobiose, laminaribiose and isomaltulose. Morales reported that New Zealand honeydew honeys contain three tetrasaccharides (maltotetraose, alpha-panasyl- D-fructofuranoside and alpha-maltosyl-D-fructofuranoside), two pentasaccharides and one hexasaccharide.
Shin reported that the oligosaccharides in honey are derived from the action of honeybee alpha-D-glucosidase which catalyses the transfer of alpha-Dglucopyranosyl groups from sucrose to an acceptor carbohydrate, and which thus results in formation of fructooligosaccharides and a variety of other oligosaccharides in varying amounts. Using an activated charcoal method of oligosaccharide extraction, Morales found variations in the higher oliogosaccharide compositions of ten different honeys.
Enzymes
Honey contains small amounts of enzymes that are introduced into honey by bees during their honey production process. Common enzymes in honey are diastase (amylase), invertase (alpha-glucosidase) and glucose oxidase. Other enzymes such as catalase and acid phosphatase are present in lesser amounts.
Glucose oxidase converts glucose in the presence of water and oxygen to gluconic acid and hydrogen peroxide. The resulting acidity and hydrogen peroxide preserves and sterilises the honey during the ripening process. Full-strength honey has negligible amounts of hydrogen peroxide and active glucose oxidase. Diastase activity is a quality factor, influenced by honey storage and heating and is thus an indicator of honey freshness. Diastase activity usually diminishes during storage.