Rheological behaviour and microstructural properties of dark chocolate produced by combination of a ball mill and a liquefier device as small scale chocolate production system

An approach to manufacturing well-being milk chocolate in partial replacement of lecithin by the functional plant-based combination

Lecithin is constituted of a glycerophospholipid mixture and is abundantly used as an emulsifying agent in various food applications including chocolate production. However, overconsumption of lecithin may create an adverse effect on human health. Thus, this study aims to replace the lecithin with plant-based gums. Different ratios of guar and arabic gum (25%-75%) and their blend (25%-75%) were employed as partial replacement of lecithin. Milk chocolate prepared using 40% guar gum (60GGL [guar gum, lecithin]), 25% arabic gum (75AGL [arabic gum, lecithin]), and a blend of 15 arabic gum and 10 guar gum (65AGGL [arabic gum, guar gum, lecithin]) showed similar rheological behavior as compared to control chocolate (100% lecithin). The fat content of 65AGGL (37.85%) was significantly lower than that of the control sample (43.37%). Rheological behavior exhibited shear-thinning behavior and samples (60GGL-75GGL-80GGL, 65AGL-75AGL, and 65AGGL-75AGGL) showed similar rheological properties as compared to control. The chocolate samples (60GGL and 65AGGL) showed significantly (p < .05) higher hardness values (86.01 and 83.55 N) than the control (79.95 N). As well, gum-added chocolates exhibited higher thermal stability up to 660°C as compared to the control sample. The Fourier transform infrared spectroscopy (FTIR) analysis revealed predominant β-(1 → 4) and β-(1 → 6) glycosidic linkages of the gums and lecithin. Sensory evaluation revealed a comparable score of gum-added milk chocolate in comparison to control samples in terms of taste, texture, color, and overall acceptance. Thus, plant exudate gums could be an excellent alternative to lecithin in milk chocolate, which can enhance the textural properties and shelf life.

Rheology of liquid foods under shear flow conditions: Recently used models

Proper modeling of flow or viscosity curves as a function of shear rate is a useful tool in any engineering activity. The rheology of foods depends on the composition, processing to which they have been subjected and the state of dispersion in which they are found. Liquid foods are complex biosystems, that show non-Newtonian behavior under flow conditions. This review presents models used in recent decades to describe the experimental rheological behavior of various liquid foods, ranging from Newtonian fluids to the most complex. Some non-Newtonian parameters such as those of the Ostwald-de Waele, Bingham, Herschel-Bulkley, Casson, Cross, and Carreau models are summarized. Examples of thixotropic behavior described by the Weltman and Abu-Jdayil models are also presented. In each model, explanations based on the composition and dispersion state of the food are made. This is useful in innovative processing technologies and for scientists new to the field of food rheology. An attempt is made to exemplify and group the expected behavior for most fluid foods, including some for a dysphagia diet, depending on their composition or the dispersed system formed, which will be useful for professionals who wish to compare reported rheological parameters with those obtained experimentally.

Cocoa polyphenols and milk proteins: covalent and non-covalent interactions, chocolate process and effects on potential polyphenol bioaccesibility

In this study, we discussed covalent and non-covalent reactions between cocoa polyphenols and proteins (milk and cocoa) and the possible effects of these reactions on their bioaccessibility, considering environmental and processing conditions. Better insight into these interactions is crucial for understanding the biological effects of polyphenols, developing nutritional strategies, and improving food processing and storage. Protein-polyphenol reactions affect the properties of the final product and can lead to the formation of various precursors at various stages in the manufacturing process, such as fermentation, roasting, alkalization, and conching. Due to the complex composition of the chocolate and the various technological processes, comprehensive food profiling strategies should be applied to analyze protein-polyphenol covalent reactions covering a wide range of potential reaction products. This will help to identify potential effects on the bioaccessibility of bioactive compounds such as low-molecular-weight peptides and polyphenols. To achieve this, databases of potential reaction products and their binding sites can be generated, and the effects of various process conditions on related parameters can be investigated. This would then allow to a deeper insight into mechanisms behind protein-polyphenol interactions in chocolate, and develop strategies to optimize chocolate production for improved nutritional and sensory properties.

Microwave Roasting as an Alternative to Convection Roasting: Sensory Analysis and Physical Characterization of Dark Chocolate

Roasting cocoa beans by means of microwave radiations seems to be a potential alternative to convection roasting, but little is known about the impact of this method on the perceived flavor profile of the chocolate. Therefore, this research focused on revealing the flavor perception of chocolate produced with microwave roasted cocoa beans assessed by both a trained panel and chocolate consumers. Samples of 70% dark chocolate produced from cocoa beans microwave roasted at 600 W for 35 min were compared with samples of 70% dark chocolate produced from cocoa beans convectively roasted at 130 °C for 30 min. Non-significant differences (p > 0.05) in the measured physical properties, such as color, hardness, melting, and flow behavior, showed that chocolate produced from microwave roasted cocoa beans can exhibit the same physical qualities as convection roasted chocolate. Moreover, combined discriminative triangle tests, with 27 judgements in total, performed by a trained panel, showed that each type of chocolate exhibited distinctive characteristics (d'-value = 1.62). Regarding the perceived flavor, "cocoa aroma" was cited as significantly higher for the chocolate produced from microwave roasted cocoa beans (n = 112) compared to chocolate produced from convection roasted cocoa beans (n = 100) by consumers. Both preference and willingness to buy were higher, though insignificant at a 5% level, for the microwave roasted chocolate. A final potential benefit (studied in this research) of microwave roasting cocoa beans is the reduced energy consumption, which was estimated at 75%. Taking all these results together, the microwave roasting of cocoa is shown to be a promising alternative to convection roasting.

Physical and Chemical Properties of 70% Cocoa Dark Chocolate Mixed with Freeze-Dried Araz&aacute; (Eugenia stipitata) Pulp

This work aimed to determine the chemical and physical properties of 70% dark cocoa chocolate, including freeze-dried Arazá (Eugenia stipitata) pulp (FDAP). We studied chocolates incorporating three FDAP concentrations (1.0, 1.5, and 2.0%). No statistical differences were found in total polyphenol content, antioxidant capacity, and total catechin and epicatechin content. The dark chocolates' moisture and texture were unaffected by the FDAP. The Casson yield stress increased to 19.67±1.35 Pa, while the Casson plastic viscosity reduced to 1.68±0.03 Pa·s, Also, the particle size increased. The dark chocolates' flow behavior corresponded to a non-Newtonian fluid. Finally, the dark chocolate's properties were unaffected by a 2% FDAP concentration.

Rheological and Functional Properties of Dark Chocolate with Partial Substitution of Peanuts and Sacha Inchi

Chocolate is a widely consumed product, due to the contribution of fats and antioxidant compounds; the addition of other components makes it possible to increase the content of polyunsaturated fatty acids, although they can affect its rheological properties. The influence of the partial addition of peanut paste and Sacha Inchi on the rheological and functional properties of dark chocolate was evaluated. Cocoa beans, peanuts, and Sacha Inchi were refined in order to obtain the cocoa paste (PC), peanut paste (PM), and Sacha Inchi paste (PSI). Then, mixtures between 0 to 20% of PM and PSI were formulated, and the rheological properties were evaluated at 30, 40, and 50 °C; these were adjusted to mathematical models. Functional groups were identified by FTIR in ATR mode, and it was observed that the partial addition of PM and PSI did not show significant changes in the shear stress and apparent viscosity of the mixture, although they did show dependence on temperature. The Herschel−Bulkley model showed a better adjustment (R2 > 0.999), reporting behavior index values, n < 1.0, and indicating pseudo-plastic behavior for pastes and formulations. The yield limit τy and the consistency index kH increased significantly with the addition of PM and PSI, but they decreased with increasing temperature. The activation energy show values between 13.98 to 18.74 kJ/mol, and it increased significantly with the addition of PM and PSI. Infrared analysis evidenced the presence of polyunsaturated fatty acids, coming mainly from PSI and PM. The addition of PM and PSI does not influence the rheological properties and allows for an increase in the content of polyunsaturated fatty acids.

Chocolate flow behavior: Composition and process effects

Chocolate is a non-Newtonian substance, and such substance has different viscosities at different shear rates. Rheological evaluations have become indispensable instruments for characterizing final chocolate, forecasting product efficiency and consumer acceptance. During production, the different steps depend on a well-defined viscosity and yield stress. Furthermore, the characteristics of the final chocolate (the surface and mouth-feel) are directly related to the chocolate's viscous behavior. There is a demand for better understanding the variables affecting chocolates flow behavior. Current research realized great insight into the chocolate flow behavior in different processes such as refining, conching, and tempering. Also, the influence of formulation and particle characteristics on flow behavior of the intermediate product and the final product were discussed. Each stage of the production process: mixing, refining, conching and tempering involves modifications of macroscopic characteristics of the chocolate ingredients thus affecting the rheological attributes of the final product. Particle size distribution and ingredient composition play substantial roles in shaping its flow behavior and sensory perception. The rheological properties of chocolate provide substantial information for food scientists to improve and optimize their products and manufacturing processes. Nowadays, a thorough understanding of chocolate flow behavior is a necessity for food scientists and industry.

Comparison of the Effects of Conching Parameters on the Contents of Three Dominant Flavan3-ols, Rheological Properties and Sensory Quality in Chocolate Milk Mass Based on Liquor from Unroasted Cocoa Beans

The content of polyphenols in chocolate depends on many factors related to the properties of raw material and manufacturing parameters. The trend toward developing chocolates made from unroasted cocoa beans encourages research in this area. In addition, modern customers attach great importance to how the food they consume benefits their bodies. One such benefit that consumers value is the preservation of natural antioxidant compounds in food products (e.g., polyphenols). Therefore, in our study we attempted to determine the relationship between variable parameters at the conching stage (i.e., temperature and time of) and the content of dominant polyphenols (i.e.,catechins, epicatechins, and procyanidin B2) in chocolate milk mass (CMM) obtained from unroasted cocoa beans. Increasing the conching temperature from 50 to 60 °C decreased the content of three basic flavan-3-ols. The highest number of these compounds was determined when the process was carried out at 50 °C. However, the time that caused the least degradation of these compounds differed. For catechin, it was 2 h; for epicatechin it was 1 h; and for procyanidin it was 3 h. The influence of both the temperature and conching time on the rheological properties of chocolate milk mass was demonstrated. At 50 °C, the viscosity and the yield stress of the conched mass showed its highest value.

Effects of polyols on the quality characteristics of sucrose-free milk chocolate produced in a ball mill

Sucrose-free milk chocolates containing different types of bulk (isomalt, xylitol and maltitol) and high intensity (Stevia) sweeteners were produced by using a ball mill. The main quality characteristics of the formulated chocolates were evaluated and compared with those of the conventional sample containing sucrose. The Casson model was the best fitting model for the rheological data. Casson viscosity and Casson yield stress were significantly affected by the type of bulking agent in chocolates formulated with xylitol (p < 0.05). However xylitol notably improved the overall acceptability according to the sensory analysis results. Chocolates containing the sucrose replacers demonstrated lower T_onset values and higher enthalpy than the control sample. Sucrose-free chocolates illustrated a higher degree of particle agglomeration. Bulk sweeteners meanwhile seem to have high potential for milk chocolate production with low calorie values by using the ball mill technique. Industrial applications: the production of sucrose-free chocolates with conventional methods requires a lot of time and energy. Recently, using alternative methods for chocolate production has been raising interest in many small industries. This study proposed a ball mill method for the preparation of sucrose-free milk chocolates with physiochemical properties almost ranging in the standard limit defined for chocolate. Although using the ball mill method presents a more cost-effective technique for chocolate production and provides shorter processing times for small chocolate industries, it seems to be less efficient in evaporating moisture than the conventional processing. Challenges are still ahead for upgrading this alternative technique to be efficient in evaporating more moisture during operation ending in a high quality product.

Sucrose-free milk chocolates containing different types of bulk (isomalt, xylitol and maltitol) and high intensity (Stevia) sweeteners were produced by using a ball mill.