Carbohydrate composition and electrical conductivity of different origin honeys from Lithuania V. Kas ˇkonien _ e a, 1 , P.R. Venskutonis a, * , V.  Ceksteryt _ e b a Department of Food Technology, Kaunas University of Technology, Radvil _ en ˛ u road 19, LT–50254, Kaunas, Lithuania b Lithuanian Institute of Agriculture, Instituto av. 1, LT–58344, Dotnuva, K _ edaini ˛ u dist., Lithuania article info Article history: Received 29 April 2008 Received in revised form 2 October 2009 Accepted 8 January 2010 Keywords: Honey Carbohydrates Electrical conductivity Melissopalynology analysis Botanical source abstract The main task of this study was to characterize Lithuanian honeys obtained from various sources by their carbohydrate composition and electrical conductivity and to determine if there is any dependence between these characteristics and pollen content. Twenty six samples of honey collected in Lithuania in 2006 during flowering season were analyzed by gas chromatography. Botanical source of honey samples was established by the melissopalynological method: 15 of analyzed samples were unifloral rape (winter and spring), 7 willow and 4 polyfloral honeys. Fructose, glucose, sucrose, maltose, isomaltose, turanose, trehalose, palatinose, cellobiose, raffinose and panose were identified and quantified in all samples. Glucose was predominant in 22 out of 26 samples. The mean values of fructose and glucose varied from 329.2 to 400.0 and from 346.0 to 426.3 mg/g honey, respectively. The amount of sucrose was 0.7–2.5 mg/ g. Some correlations between sugar concentration and the content of pollen were established. The ratios of fructose/glucose, maltose/isomaltose, maltose/turanose, sucrose/turanose, which may be used as indicators for honey authenticity, were calculated. In addition, electrical conductivity was measured and it was found that it varied from 0.27 to 0.89 mS/cm. Unifloral rape honeys had the lowest electrical conductivity. Data obtained was thoroughly compared with previously published results and it was found that the characteristics of Lithuanian honeys in most cases meet international requirements for natural honey. However, the information on honey sugar composition and electrical conductivity was not sufficient for the reliable determination of the botanical origin of honey. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Honey is a unique food product consisting of carbohydrates, amino acids, proteins (including enzymes), organic acids, vita- mins, minerals and various phytochemicals. Honey is produced by bees from the nectar collected from a large variety of flowers and its chemical composition, physical, sensory and biological prop- erties depend on the nectar source (Anklam, 1998; Persano Oddo, Piazza, Sabatini, & Accorti, 1995). Moreover, physicochemical characteristics of honey may depend even on the bee species (Joshi, Pechhacker, Willam, & von der Ohe, 2000) and geograph- ical origin of honey (Anklam, 1998; Da Costa Leite et al., 2000; Radovic et al., 2001). A great number of factors influencing honey composition and properties make the product an interesting topic for research. In general, honey is a supersaturated sugar solution; sugars are the main constituents of honey accounting for about 95 g/100 g dry matter. Fructose and glucose are major sugars, the former one being a dominant component almost in all honey types, except for some honeys of rape (Brassica napus), dandelion (Taraxacum officinale) and blue curls (Trichostema lanceolatumi) origin, when glucose is present in higher amounts (Cavia et al., 2002). In addition, disac- charides, trisaccharides and other oligosaccharides are present in honey in small concentrations. The concentration of fructose and glucose as well as their ratio are useful indicators for the classifi- cation of unifloral honeys (Persano Oddo et al., 1995; Persano Oddo & Piro, 2004). It is known that there are compositional differences between honeydew and blossom honeys. Honeydew honey is characterized by a higher concentration of oligosaccharides, mainly trisaccha- rides melezitose and raffinose, which usually are not found in blossom honeys (Bogdanov, Ruoff, & Persano Oddo, 2004). Honey has been produced in Lithuania from the ancient times. Recently, we reported antimicrobial and antioxidant properties of Lithuanian honeys (Baltrus ˇaityt _ e, Venskutonis, &  Ceksteryt _ e, 2007a; Baltrus ˇaityt _ e, Venskutonis, &  Ceksteryt _ e, 2007b), while * Corresponding author. Tel.: þ370 37 300188; fax: þ370 37 456647. E-mail address: rimas.venskutonis@ktu.lt (P.R. Venskutonis). 1 Present address: Department of Biochemistry and Biotechnologies, Vytautas Magnus University, Vileikos str. 8, LT-44404 Kaunas, Lithuania. Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt 0023-6438/$ – see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.lwt.2010.01.007 LWT - Food Science and Technology 43 (2010) 801–807