Rheological Aspects of Spanish Honeys

Stabilization activity of a new protein-carbohydrate complex in sesame paste: rheology, microstructure, and particle size analysis

BACKGROUND

Sesame protein concentrate is a by-product of sesame processing with great nutritional and functional value. In the present study, sesame protein concentrate and a conjugated form of the protein with maltodextrin were applied to improve stability and texture of sesame paste. The rheological properties of samples were studied using dynamic measurement, controlled rate and controlled stress rheological analysis, and creep analysis to investigate the sesame paste structure and to illustrate the mechanism of their stability against oil separation.

RESULTS

Samples containing the conjugate showed good stability, low average droplet size and uniform microstructure. Creep analyses showed as the conjugate was added to sesame paste, μ₀ and μ₁ values (corresponding dashpot viscosities) were higher than that of G₀ and G₁ (shear moduli of Maxwell and Kelvin-Voigt springs). Dynamic shear test exhibited increased storage modulus (G') and loss modulus (G″) by the increase in frequency and elastic structure of sesame paste converted to viscose behavior with the contribution of conjugate.

CONCLUSION

Particle interaction in sesame protein concentrate (SPC)-maltodextrin conjugate (SMC), may be overcome by steric repulsion force. Furthermore, impression of a weak network structure can be observed. These phenomenon could resolve the phase separation problem of traditional sesame paste. © 2022 Society of Chemical Industry.

Rheological behavior of honey adulterated with agave, maple, corn, rice and inverted sugar syrups

The aim of this study was to assess the influence of different adulteration agents (agave, maple, corn, rice and inverted sugar) on honey rheology. There was studied the influence of different percentages of adulteration agent on steady state and dynamic state rheology but also on rheology in the negative temperature domain. The authentic honey and adulterated ones behaved as a Newtonian fluid with a liquid-like behavior (G">>G'). Regarding the physicochemical parameters analyzed (moisture and sugar content), significant changes depending on the adulteration agent/degree used were observed. The viscoelastical parameters (η*-complex viscosity, G' -elastic modulus and G"-viscous modulus) and glass transition temperature (Tg) were predicted in function of the chemical composition (moisture content, glucose, fructose, sucrose, maltose, raffinose, trehalose, turanose, melesitose, and F/G ratio) using the PLS-R (partial least square regression). All parameters analyzed had a high regression coefficient for calibration (> 0.810) and validation (> 0.790), except for the elastic modulus.

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).

Characteristics of the bitter and sweet honey from Algeria Mediterranean coast

Aim

This study aimed to compare the physicochemical, the biochemical, and the antioxidant characteristics of unifloral bitter honey and polyfloral sweet honey.

Materials and Methods

Unifloral bitter and polyfloral sweet honey samples were, respectively, harvested in January and July, and then, they were extracted by the traditional method. The markers of refractive index, pH, free acidity, Brix index, density, reducing sugars, total polyphenols, flavonoids, tannins, 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing/antioxidant power (FRAP) were evaluated.

Results

The obtained results showed that the physicochemical parameters are within the normal ranges, in which they meet the international standards (Codex Alimentarius). For biochemical constituents, matching concentrations of reducing sugars (glucose+fructose) were observed in both samples, while that of sucrose were very low in unifloral than polyfloral honey. The levels of the active ingredients showed a difference in total polyphenols and tannins of the two types of honey studied, whereas that of flavonoids were almost similar. The antioxidant activity of various samples evaluated by DPPH and FRAP indicated that unifloral has a superior activity.

Conclusion

Compared to polyfloral honey, unifloral bitter honey has lower sucrose, high total polyphenols, and tannins levels, in addition to higher antioxidant potential.

Honey authentication using rheological and physicochemical properties

The aim of this study was to evaluate the influence of honey botanical origins on rheological parameters. In order to achieve the correlation, fifty-one honey samples, of different botanical origins (acacia, polyfloral, sunflower, honeydew, and tilia), were investigated. The honey samples were analysed from physicochemical (moisture content, fructose, glucose and sucrose content) and rheological point of view (dynamic viscosity-loss modulus G″, elastic modulus G', complex viscosity η*, shear storage compliance-J' and shear loss compliance J″). The rheological properties were predicted using the Artificial Neural Networks based on moisture content, glucose, fructose and sucrose. The models which predict better the rheological parameters in function of fructose, glucose, sucrose and moisture content are: MLP-1 hidden layer is predicting the G″, η* and J″, respectively, MLP-2 hidden layers the J', while MLP-3 hidden layers the G', respectively. The physicochemical and rheological parameters were submitted to statistical analysis as follows: Principal component analysis (PCA), Linear discriminant analysis (LDA) and Artificial neural network (ANN) in order to evaluate the usefulness of the parameters studied for honey authentication. The LDA was found the suitable method for honey botanical authentication, reaching a correct cross validation of 94.12% of the samples.

Temperature dependent steady and dynamic oscillatory shear rheological characteristics of Indian cow milk (Desi) ghee

Rheological characteristics of Desi ghee were investigated at 18, 24, 30 and 36 °C. The steady shear properties were evaluated by varying the shear rate from 0.01 to 100 s^-1 and the dynamic shear properties were studied by varying strain and frequency sweep from 0.01 to 100% and 0.1 to 100 rad s^-1, respectively. At the four selected temperatures, the ghee samples displayed non-Newtonian shear thinning behavior with flow behavior index (n) ranging from 0.224 to 0.911. As the shear rate increased from 0 to 100 s^-1, the values of dynamic viscosity decreased from 54 to 8.14, 20.01 to 1.05, 1.33 to 0.295, and 3.02 to 0.0025 Pa s at 18, 24, 30 and 36 °C, respectively. Out of four rheological models (Power-law or Ostwald-de Waele, Herschel-Bulkley, Casson, and Bingham model) fitted to the shear rate and stress data, the Ostwald model was found to be superior in predicting the shear rate-stress data at 18 °C, whereas Ostwald-de Waele and Herschel-Bulkley models predicted all the data points over the temperature range of 24-30 °C, as observed by the values of coefficient of determination (R² ), standard deviation (SD), and relative deviation percentage (R_d ). The value of activation energy (E_A ), as calculated from Arrhenius type equation, was found to be 1.98 × 10⁶ kJ mol^-1 over the entire temperature range. The study also revealed that the magnitudes of dynamic shear viscosity (η*) were higher than those of the steady shear viscosity (η) at the four temperatures, indicating that the Cox-Merz rule was not applicable to the ghee samples.

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.

The flow properties of honey-malt spread

In this study, the effect of barley malt extract at two brix levels (74 and 79 °Bx) and three ratios of malt extract/honey (65:35, 70:30 and 75:25) on the flow behavior properties of honey-malt spread at three temperature levels (35 ℃, 45 ℃ and 55 ℃) was investigated. Time-dependent behavior data of the spread samples were appropriately fitted to the Weltman, first-order stress decay with a zero stress value and first-order stress decay with a non-zero stress value models. Also, the Power-law, Herschel-Bulkley, Casson and Bingham models were used for curve fitting the time-independent behavior data. Regarding the R² and root mean square error coefficients, the first-order stress decay with a non-zero stress value and Herschel-Bulkley models were selected as the suitable models to describe the flow behavior of samples. The results for time-dependent properties showed that spread samples exhibit a thixotropic behaviour, as the viscosity for all samples decreased with increase in shearing time at a constant shear rate of 50 s^-1.

Rheological and some physicochemical characteristics of selected floral honeys from plants of caatinga

The aim of this paper was to investigate the physicochemical characteristics and rheological behavior of some floral honeys from species of wild plants found in the Caatinga biome, as well as, correlate honey viscosities with its chemical composition. Thus, five honeys with floral predominance of typical plants foraged by honeybees in Caatinga were analyzed. Results showed that moisture content of honeys ranged from 17.45 to 21.50 g/100g. The samples exhibited higher fructose content (37.58 - 43.95 g/100g) and lower glucose content (27.41- 33.80 g/100g). The glucose-water ratio ranged from 1.55 to 1.80. Sucrose contents, excluding Croton campestris honey sample, exhibited values above the highest sucrose content (6.0 g/100g) allowed by Brazilian norm. The ash content ranged from 0.02 to 0.19 %. The insoluble solids content were above 0.1 g/100 g. The electrical conductivity ranged between 144.90 and 412.55 µS.cm–1. All the honey samples behaved as Newtonian fluids. The viscosity values, measured at 293 K, varied from 1.90 to 8.55 Pa.s. An empirical mathematical model adapted from the Arrhenius model provides a good description of honey viscosity as a function of combined effects of temperature and moisture content.