EUROFOODCHEM XVII, MAY 07-10, 2013, İSTANBUL SOME CHEMICAL PROPERTIES OF COMMERCIAL HONEYS CONSUMED IN ISTANBUL Harun URAN1 Filiz AKSU1 Dilek DÜLGER1 Istanbul Aydın University Anadolu Bil Professional School of High Education, Food Processing Department, TR 34295 Istanbul/Turkey harunuran@aydin.edu.tr, filizaksu@aydin.edu.tr, ddilekdulger@gmail.com The quality and biochemical properties of honey are related to honey maturity, production methods, processing and storage conditions, climatic conditions as well as the nectar source of the honey. The some chemical properties of 35 honey samples purchased in the İstanbul region of Turkey were determined in this study. The biochemical characterizations were as follows: average moisture (%16.31±1.40), ash (%0.30±0.29), hydroxymethylfurfural (HMF) (8.09±7.63 mg/kg), pH (4.32±0.34), acidity (% 0.30±0.09). Honey is a concentrated solution of glucose and fructose with other minor sugars. Honey, produced by honeybees from nectar in flowers and plants, is an aqueous 40 supersaturated sugar solution, mainly composed of fructose and glucose. Moreover, honey contains certain minor constituents like minerals, and other saccharides, proteins, enzymes, aminoacids, vitamins, organic and phenolic acids, flavonoids, carotenoids, volatile substances and products of the Maillard reaction. Honey is submitted to thermal treatments for two different reasons: (1) to modify its tendency to crystallisation or delay its appearance and (2) to destroy the micro-organisms which contaminate it. HMF is formed in honey via hexose dehydration and Maillard reaction (Tosi et al. 2002). HMF is used as an indicator of freshness and degree of heat treatment applied during processing of honey. Honey with high HMF content is sold as an ingredient for food production. (Terrab et al. 2002). Quality reduction in honey during storage is indicated by hydroxymethylfurfural (HMF) accumulation and darkening of color. The effects of moisture content and temperature on HMF accumulation and color change in honey during storage were investigated (Bulut and Kılıc 2008). Materials and Methods Materials Investigation, which is the subject of honey samples as packaged were taken from different parts of Istanbul and delivered to the laboratory for analysis. All samples were stored in their original packages at 4-5 oC until analysis. Honey samples were taken from each sample in homogeneous and analyzes carried out paralleled. Methods To determine the chemical composition of honey samples moisture, ash, pH, acidity and HMF analaysis were made. Moisture and ash analyzes were determinated on the basis of weight loss (AOAC 1990); pH values were measured using Hanna pH meter and total acidity were calculated with titration method as malic acid . Spectrophotometric method were used for the determination of the amount of HMF. 2 mL of diluted honey samples transferred to test tubes, and 5 ml solution of p-toluidine was added on them. Then added 1 mL of pure water to be used as blank test tube, barbituric acid solution was added 1 mL to the test tube. The tubes were mixed well and the absorbance of the test tubes were determined to blank sample in spectrophotometer used 550 nm wavelenght. HMF quantities of samples were detected out of the standard curve (Cemeroğlu 2007). The mean of HMF was found 8,09±7,63 mg/kg with the range of 1,08 to 30,69 mg/kg in our study. Significantly lower levels than the data were reported for honeys from France (3.28 mg/kg), Italy (7.80 mg/kg,) and Turkey (25.9 mg/kg). Mendes et al. (1998) reported HMF levels in the range of 1.7–471 mg/kg. Maximum concentration of HMF that could be present in honey is 40 mg/kg according to the national codex (Anon 2005). Analysis Minimum Maximum Mean Standard deviation Moisture (%) 14.11 19.66 16.31 1.40 Ash (%) 0.009 0.80 0.30 0.29 Total acidity (g/100 g) 0.13 0.46 0.09 pH 3.75 5.19 4.32 0.34 HMF (mg/kg) 1.07 30.69 8.09 7.63 The natural moisture of honey in the comb is that remaining from the nectar after ripening. Moisture content is one of the most important factors affecting the rate of deterioration reactions in food products. The moisture content of honey varies in the range of 12–24% depending on its source Anonymous. 2005. Turkish Food Codex Standard for Honey (No:2005/49), Official Gazette 26026/17.12.2005, Turkish Prime Ministership, Ankara, Turkey. Tosi, E.A., Ciappini, M., RE, E. and Lucero, H. 2002. Honey thermal treatment effect on hydroxymethylfurfural content. Food Chem. 77, 71–74. Terrab, A., Diez, M. J., & Heredia, F. J. 2002. Characterization of Moroccan unifloral honeys by their physicochemical characteristics. Food Chemistry, 79, 373–379. Oddo, L. P., & Bogdanov, S. 2004. Determination of honey botanical origin: Problems and issues. Apidologie, 35, S2–S3. Devillers, J., Morlot, M., Pham-Delegue, M. H., & Dore, J. C. 2004. Classification of monofloral honeys based on their quality control data. Food Chemistry, 86, 305–312.. By J. W. Whıte, Jr. And Landıs W. Doner, Research leader and research chemist, respectively, Science and Education Administration, Eastern Regional Research Center, Philadelphia, Pa. 19118. Bulut L., Kılıç M. 2008. Kınetıcs of hydroxymethylfurfural accumulatıon And color change ın honey durıng storage ın Relatıon to moısture content. Journal of Food Processing and Preservation 33 (2009) 22–32. AOAC 1990. Official Methods of Analyses of Association of Analytical Chemist. Fifteen Edition, Washington DC. Kurt A., Karadeniz R 1982. Erzurum İli Merkezinde Tüketilen Süzme Ballar Üzerinde Bir Araştırma. Gıda, 7 (3): 115-120.  Cemeroğlu B. 2007. Gıda Analizleri. Gıda Teknolojisi Derneği Yayınları, p: 167-171, Ankara. Conclusion: The extents of HMF accumulation and color change in honey during storage are also expected to depend on its type (composition, pH). HMF accumulated and color darkened in honey depending on both moisture content and temperature during storage. It is important that the essential precautions should be taken to ensure standardisation and rationalisation of beekeeping techniques, manufacturing procedures and storing processes to improve honey quality.