Physico-chemical, rheological, calorimetric and dielectric behavior of selected Indian honey Jasim Ahmed * , S.T. Prabhu, G.S.V. Raghavan, M. Ngadi Department of Food Science and Agricultural Food Chemistry, Bioresource Engineering, McGill University, Macdonald Campus, 21111 Lakeshore, Ste Anne de Bellevue, Que., Canada H9X 3V9 Received 22 November 2005; accepted 11 April 2006 Available online 12 May 2006 Abstract Physico-chemical, thermal, rheological and dielectric characteristics of seven Indian honey samples obtained from various floral sources were investigated. The samples were found to differ from each other in pH, ash content and visual color values. Oscillatory rhe- ology data revealed that viscous component predominates over elastic modulus (G 00 > G 0 ) and some of the honey samples exhibited non- Newtonian behavior with definite yield stress. The inflection glass transition temperature (T g ) of the honey samples varied between 51.14 and 33.64 °C whereas the temperatures of fusion were ranged between 203 and 221 °C. Few cases more than one fusion tem- perature of honey samples indicated that melting of different sugar components occurred at different temperatures. Both dielectric con- stant (e 0 ) and loss factor (e 00 ) of honey samples decreased in general as function of frequency at 20 °C. Dielectric parameters of honey were governed by both moisture and ash content of samples. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Honey; Total soluble solids; Color; Viscous modulus; Dielectric constant; Loss factor; Glass transition temperature; Temperature of fusion 1. Introduction Honey is natural complex food product produced by bees from nectar of plants and also from honeydew. It is a unique sweetening agent that can be used by humans without processing. Bee honey has significant nutritional and medicinal benefits. It is a rich source of readily avail- able sugars, organic acids, various amino acids and in addi- tion source of many biologically active compounds. Western Ghats in India produces wide variety of vegetation and almost one-third of all the flowering plant species in India are found in those regions. Currently, characterization of honey by means of chem- ical, rheological and sensory characteristics has received several attentions (Anklam & Radovic, 2001; Cordella, Militao, Clement, & Cabrol-Bass, 2003; Iglesias, de Lore- nzo, Polo, Martı ´n-A ´ lvarez, & Pueyo, 2004). Plenty of liter- atures are available on physico-chemical, rheological and quality aspects of honey produced in different countries which is evident from publication in a single year on the topic (Corbella & Cozzolino, 2006; Juszczak & Fortuna, 2006; Ouchemoukh, Louaileche, & Schweitzer, 2006; Yan- niotis, Skaltsi, & Karaburnioti, 2006). A vast country like India too produces honey from various floral sources with wide variations in physico-chemical, functional and rheo- logical characteristics. Rheological parameters have been considered as an ana- lytical tool to provide fundamental insights on the struc- tural organization of food and play an important role in fluid heat transfer. Knowledge of the rheological character- istics of honey is very important from storage and handling point of view (Assil, Sterling, & Sporns, 1991). However, most of the cases steady shear viscosimetry has been employed to characterize the rheological properties of honey which indicated is honey as a Newtonian fluid (Abu-Jdayil, Ghzawi, Al-Malah, & Zaitoun, 2002; Juszc- zak & Fortuna, 2006; Mossel, Bhandari, D_Arcy, & Caffin, 0260-8774/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2006.04.048 * Corresponding author. Tel.: +1 5146 314390; fax: +1 5143 987977. E-mail address: jahmed2k@yahoo.com (J. Ahmed). www.elsevier.com/locate/jfoodeng Journal of Food Engineering 79 (2007) 1207–1213