Chocolate flow behavior: Composition and process effects

Chocolate microstructure: A comprehensive review

Chocolate is a food with complex microstructure properties. In this study, chocolate surface and internal microstructures are discussed considering final product quality and stability. In addition, the effects of the solids and continuous phase components and the interactions between them, and also process effects on the microstructure were reviewed. Irregularities in the internal microstructure affect the surface and cause problems such as unstable cocoa butter crystals, a whitish, streaky appearance, chewy especially fat bloom in this layer and in general, a low quality and sensory in final product. Optimization of the particle size and cooling conditions of the solids is required to modify the surface topography for roughness and pores morphology. Reducing surface porosity can increase fat bloom resistance. For this purpose, reducing surface hydrophobicity by considering proteins with di-sulfide bonds and their concentrations and the use of different bulk sweeteners should be taken into consideration. The morphology of the surface microstructure may be used for product characterization as well as to investigate the environmental conditions exposed during processing and storage. It should be noted that chocolate has a three-phase microstructural system, considering the air present in the gaps at the interface. The importance of the third phase for continuous phase mobility is critical. Additionally, this phase affects behavior in the oral cavity due to melting and release of volatile components.

Structural and sensory impact of various emulsifiers in cocoa hazelnut spread formulations

In this study, the effects of emulsifiers such as lecithin, AMPs, Palsgaard® Oil-Binder and GMS on cocoa hazelnut spread rheology were compared under the same process conditions and formulation. Emulsifiers were added to the formulation separately at rates of 0.3%-0.4%-0.5%. Hardness values in cocoa hazelnut spread were examined at 15-day intervals until the 60th day. In addition, viscosity, rheological analyses, color, spreadability, stability tests, and sensory analyses were performed. In the production of cocoa hazelnut spread, lecithin and AMP have less hardness and lower viscosity, greater fluent consistency, better spreadability, and lower "work of shear" values compared with other emulsifiers. The emulsifier type/ratio difference did not affect the color value statistically. It was determined that the use of Oil-Binder and GMS significantly protected the stability compared with other emulsifiers. During the 60-day storage period, lecithin preserved its hardness properties better than other emulsifiers. When sensory properties were examined, the use of lecithin and AMP in cocoa hazelnut spread samples scored high in brightness, spreadability, mouthfeel, and taste parameters. As a result, lecithin comes to the fore in the use of different types and ratios of emulsifiers in cocoa hazelnut spread production technology.

Flow properties of single origin chocolates: Effect of product formulation and particle size

The objective of this research was to evaluate changes in flow behavior of chocolate during chocolate grinding using a stone grinder as affected by chocolate formulation. Three different types of chocolates were evaluated. Two chocolates without milk added (70% chocolate) and two chocolates with milk added and with different amounts of cocoa nibs (30% chocolate and 14% chocolate) were tested. For the 70% chocolates, nibs of two different origins were used; therefore, a total of four samples were evaluated. Chocolates were processed in a stone grinder, and samples were taken as a function of grinding time. For each timepoint, the flow behavior of the samples was measured using a rotational rheometer and fitted to the Casson model. Particle size was measured using a laser scattering instrument. Results showed that yield stress increased linearly while the Casson plastic viscosity decreased exponentially with grinding time (smaller particles). Particle size distribution of the chocolates showed a prominent bimodal distribution for short grinding times (∼9 h) with small (∼15 µm) and large (∼100 µm) particles; with longer grinding time, the population of larger particles decreased. Yield stress values were higher for the 70% chocolate, but they were not very different between the two milk chocolates tested. The Casson plastic viscosity was greatest for the 70% chocolate, followed by the 30% chocolate. The 14% chocolate had the lowest Casson plastic viscosity. Changes of Casson plastic viscosity with particle size were more evident for the dark chocolates compared to the milk ones. These results are helpful to small chocolate producers who need better understanding of how the formulation and grinding of chocolate affect its flow behavior, which will ultimately affect chocolate handling during production.

Sugar reduction in chocolate compound by replacement with flours containing small insoluble starch granules

Consumer concern about intake of added sugars has increased commercial demand for sugar-reduced chocolates. However, substitution with high-potency sweeteners is not possible as sugar serves as an important bulking agent. Here, we investigated replacement of sucrose in chocolate compound with oat or rice flours, with starch granules smaller than 10 µm, focusing on texture, sweetness, and acceptability. In Study 1, six chocolates were made: a control with 54% sucrose, four sucrose-reduced versions (reductions of 25% or 50%, using either oat or sweet rice flour), and one 54% sucrose chocolate with reduced refining time. These chocolates were compared in a Difference from Control (DFC) test in a within-subject design, with and without nose clips. Particle size distribution, yield stress, and plastic viscosity were measured. Chocolates with 25% sucrose reduction by either sweet rice or oat flour (or reduced refining time) were not significantly different from the blind control (p > 0.05), regardless of nose clip use. In open-ended comments, participants reported differences in rice-flour-containing chocolates were due to a chalkier texture, while oat-flour-containing chocolates were described as smoother, softer, and creamier. DFC scores from the chocolates were positively correlated with plastic viscosity and negatively correlated with yield stress. In Study 2, 25% reduced sugar chocolates made with rice flour were liked significantly less than control, but the oat flour sample did not differ from control. Collectively, these results suggest up to 25% of sucrose in chocolate can be replaced with oat flour without negatively affecting texture or consumer acceptance.

Raman Spectroscopic and Sensory Evaluation of Cocoa Liquor Prepared with Ecuadorian Cocoa Beans Treated with Gamma Irradiation or Induced Electromagnetic Field Fermentation

Cocoa liquor is the primary precursor of the worldwide highly appreciated commodity chocolate. Its quality depends on several factors, such as the type of cocoa, the fermentation process, and the control of the contaminants in the fermented beans. This study aims to evaluate whether the induced magnetic field treatment during the fermentation process or the pathogen reduction with gamma irradiation after the fermentation affect the characteristics of the cocoa liquor obtained from Ecuadorian cocoa beans. For this purpose, liquor samples from controls (standard process), from beans treated with an induced magnetic field up to 80 mT, and from beans irradiated with nominal doses up to 3 kGy were characterized through Raman spectroscopic analysis and sensorial evaluation. The most relevant bands of the cocoa liquor were assigned according to reports from the literature, spectroscopic data, and chemometrics. The spectra corresponding to different treatments and doses were visually very similar, but they could be discriminated using OPLS-DA models, where the most intense Raman signals were attributed to the lipid components. The sensorial evaluation rated the presence of floral, fruity, almondy, acid, and bitter flavors, along with astringency and intense aroma, and these attributes exhibited variable behavior depending on the dose of the irradiation or magnetic treatment. Therefore, both treatments may exert an influence on cocoa beans and, therefore, on the cocoa liquor quality.

Fortification of chocolates with high-value-added plant-based substances: Recent trends, current challenges, and future prospects

High consumption of delicious foods, such as chocolates, is considered excellent snacks, capable of converting from health-threatening to great functional foods. The fortification of chocolates with high-value-added plant-based substances might improve their healthful effects, nutritional properties, and shelf life. Chocolate could be an effective carrier for plant-based substances delivery, and it could be an effective vehicle to treat and reduce the indications of disease, such as obesity, overweight, hypertension, stress, cardiovascular failure, congestive heart failure, and diabetes. Referring to the recent studies in chocolate fortification with high-value-added plant-based substances, it seems that the recent trends are toward its therapeutic effects against noncommunicable diseases. Despite the undeniable functional effects of fortified chocolates, there are some challenges in the fortification way of chocolates. In other words, their functional characteristics, such as rheological and sensory attributes, may undesirably change. It seems that encapsulation techniques, such as spray drying, antisolvent precipitation, nanoemulsification, and liposomal encapsulation, could almost overcome these challenges. Thus, several studies focused on designing and fabricating nanoscale delivery systems with the aim of chocolate fortification, which is discussed.