Rheological and Thermal Properties of Selected Brazilian Honeys from Various Floral Origins

The rheological and thermal properties of honeys have a practical importance for beekeepers and industries, as their determination allows their proper processing and quality control. However, few studies have been carried out in this area with Brazilian honeys. Therefore, physicochemical, rheological and thermal properties of 40 Brazilian honeys of different floral origins were determined in this study. All the physicochemical properties indicated that the analyzed honey samples met the criteria for honeys established by Codex Alimentarius. The honeys showed non-Newtonian behavior from 10C to 15C and Newtonian behavior from 20C to 30C with the influence of temperature on viscosity and on the viscous modulus (G) described by the Arrhenius models. Oscillatory rheological data revealed a liquid-like behavior (G> elastic modulus (G)) of the honeys. The glass transition temperature (T-g) of the honeys varied between -46.7C and -43.7C. By the principal component analysis (PCA), the first component explained 70.0% of the variation of the data, forming two groups described by moisture content, a(w), viscosity (10C to 30C), G and T-g. This analysis confirms the important influence of the moisture content and of a(w) in the rheological and thermal properties of honeys and provide useful information for the industrialization of honey and honey-based products. Practical ApplicationDetermining the honey rheological and thermal properties allows its proper processing and quality control, preventing the waste of economic resources. Conclusions for beekeepers and industries are: the honey physicochemical properties are in conformity with the Brazilian legislation and the Codex Alimentarius, which could be used by consumers and the food industry; rheological and thermal properties are inversely correlated with the moisture content and with a(w), and could be used to distinguish Brazilian honeys; Brazilian honeys behave as diluted materials, and their viscosity is temperature- and floral origin-dependent. Determining their viscosity helps in the performance, sizing and selection of equipment such as pumps, mixers, filters, centrifuges and heat exchangers; temperature fluctuations induce physical and chemical alterations in the honey, and temperature control during its processing and storage is important for maintaining its quality. All of these parameters provide useful information for the development of new products, optimization of industrial processes and control of quality and authenticity of honeys.