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

Quality of honeys from different botanical origins

Botanical origin is one of the principal factors influencing the composition and quality of honey. This study aimed to evaluate different single-flower (assa-peixe, coffee, eucalyptus, laranjeira, and vassourinha), polyfloral (silvestre), extrafloral (sugarcane), and honeydew (bracatinga) honeys with regard to their chemical, physicochemical, and physical properties; rheological behavior; bioactive compounds; and antioxidant activity. In addition, we assessed their sensory characteristics using the acceptance test and the check-all-that-apply test (CATA). All honeys were compliant with current legislation and presented Newtonian behavior. The honeys of assa-peixe, laranjeira, and coffee presented the highest viscosity, sugarcane honey showed the highest antioxidant activity, and the bracatinga honey had the highest phenolic compound content. With respect to sensory characteristics, floral honeys presented higher acceptability than did honeydew and extrafloral honeys, because honey from honeydew was negatively influenced by its bitter, alcoholic, and astringent taste and extrafloral honey by its burnt smell. These findings indicate that the botanical origin directly influences the characteristics of honeys and can be considered a factor for their differentiation.

Analytical Rheology of Honey: A State-of-the-Art Review

Honey has been used as a nutraceutical product since ancient times due to its nutritional and medicinal properties. Honey rheology influences its organoleptic properties and is relevant for processing and quality control. This review summarizes the rheological behaviour of honeys of different botanical source(s) and geographical locations that has been described in the literature, focusing on the relation between rheological parameters, honey composition (moisture, water activity, sugar content, presence of colloidal matter) and experimental conditions (temperature, time, stress, shear rate). Both liquid and crystallized honeys have been addressed. Firstly, the main mathematical models used to describe honey rheological behaviour are presented highlighting moisture and temperature effects. Then, rheological data from the literature regarding distinct honey types from different countries is analysed and results are compared. Although most honeys are Newtonian fluids, interesting shear-thinning and thixotropic as well as anti-thixotropic behaviour have been described for some types of honey. Rheological parameters have also been successfully applied to identify honey adulteration and to discriminate between different honey types. Several chemometric techniques have also been employed to obtain the complex relationships between honey physicochemical and rheological properties, including partial least squares (PLS), principal component analysis (PCA) and artificial neural networks (ANN).

A comparative study of texture and rheology of Argentinian honeys from two regions

The rheological and textural properties of 26 eastern Argentinian honeys from two different regions (North and Central) were investigated. The viscosity curves of the samples were obtained using a rotational rheometer over a temperature range of 10 to 50C. The viscosity decreased with temperature and all honeys showed a Newtonian behavior. The temperature dependence of viscosity was described using the Arrhenius, Williams-Landel-Ferry, Vogel-Taumman-Fulcher, and Power Law models. The glass transition temperatures of honeys were measured with differential scanning calorimetry and values ranged from -42.63 to -47.71C. The glass transition temperature was also predicted with the Williams-Landel-Ferry model and no significant differences were observed with the experimental results. Rheological parameters were obtained by small amplitude oscillation experiments. Results indicated that the viscous modulus was higher than the storage modulus within all the frequency ranges assayed and honeys from the North region were more viscous. Results of the back extrusion test showed that honeys from the Central region are harder and both groups of honeys (North and Central) exhibited the same consistency and adhesivity.

PRACTICAL APPLICATIONS

The honey chain production starts with the extraction of the product from the combs, pumping it through pipes and finishes at the packaging of the product. During all these stages, honey viscosity is a key parameter to ensure proper processing and quality control, preventing the waste of economic resources. Determining honey viscosity is of great importance for the industry to select the equipment such as pumps, mixers, filters, centrifuges, heat exchangers, and optimization of industrial processes. The rheological and textural properties of honey are very important in terms of applications related to quality control and authenticity of honeys. Honey authenticity increases the trust of consumers to certified food products. Argentina is one of the leading honey producers and exporters in the world, but information on the rheological, thermal, and textural characteristics of Argentinian honey is very poor in the scientific literature.