Casson Yield Stress Research Articles

Pea protein isolate-kappa-carrageenan complex coacervate as a lecithin substitute and their effect on physical properties, polymorphism, and melting behaviour of dark chocolates

This study used pea protein isolate (4% w/w) and kappa-carrageenan (4% w/w) to prepare complex coacervate through electrostatic interactions by optimizing the pH and ratio of protein-to-polysaccharide. The maximum coacervate yield of 81% was achieved at the optimized pH of 3.0 and the protein-to-polysaccharide ratio of 4:1. The optimized coacervate at various concentrations (1, 1.5, 2, 2.5, and 3% w/v) was assessed to emulsify cocoa butter to water fractions. The 2% w/v of complex coacervate successfully emulsified up to 40% aqueous phase in cocoa butter to water fractions whereas complex coacervates at 1%, 1.5%, 2.5%, and 3% w/v were found to stabilize only 20% aqueous phase. The storage and temperature stability of emulsions were higher upon usage of 2% w/v complex coacervate as the serum layer separation was minimal. Based on the emulsion stability observations, complex coacervate (2% w/v) was used to partially and completely substitute lecithin in dark chocolates. The results showed that irrespective of the emulsifiers utilized, the polymorphism and melting behaviour of all chocolates remained the same and retained the desired polymorphic form V. The moisture content and particle size distribution of chocolates did not exceed the acceptable limit. The Casson plastic viscosity (ηca), Casson yield stress (τ0c), and hardness (N) of chocolates significantly (p < 0.05) increased upon increasing the complex coacervate. The present findings revealed that partial substitution (50%) of lecithin with complex coacervate is highly promising for the production of dark chocolates while retaining the desirable flow properties and polymorphism.

Comparison of four rheological models for estimating viscosity and rheological parameters of microwave treated Basil seed gum

Dispersion of Basil seed gum has high viscosity and exhibits shear-thinning behavior. This study aimed to analyze the influence of microwave treatment (MT) at various time intervals (0, 1, 2, and 3 min) on the viscosity and rheological behavior of Basil seed gum dispersion (0.5%, w/v). The finding of this study revealed that the apparent viscosity of Basil seed gum dispersion (non-treated dispersion) reduced from 0.330 Pa.s to 0.068 Pa.s as the shear rate (SR) increased from 12.2 s−1 to 171.2 s−1. Additionally, the apparent viscosity of the Basil seed gum dispersion reduced from 0.173 Pa.s to 0.100 Pa.s as the MT time increased from 0 to 3 min (SR = 61 s−1). The rheological properties of gum dispersion were successfully modeled using Power law (PL), Bingham, Herschel–Bulkley (HB), and Casson models, and the PL model was the best one for describing the behavior of Basil seed gum dispersion. The PL model showed an excellent performance with the maximum r-value (mean r-value = 0.942) and the minimum sum of squared error (SSE) values (mean SSE value = 5.265) and root mean square error (RMSE) values (mean RMSE value = 0.624) for all gum dispersion. MT had a considerable effect on the changes in the consistency coefficient (k-value) and flow behavior index (n-value) of Basil seed gum dispersion (p < 0.05). The k-value of Basil seed gum dispersion decreased significantly from 3.149 Pa.sn to 1.153 Pa.sn (p < 0.05) with increasing MT time from 0 to 3 min. The n-value of Basil seed gum dispersion increased significantly from 0.25 to 0.42 (p < 0.05) as the MT time increased. The Bingham plastic viscosity of Basil seed gum dispersion increased significantly from 0.029 Pa.s to 0.039 Pa.s (p < 0.05) while the duration of MT increased. The Casson yield stress of Basil seed gum dispersion notably reduced from 5.010 Pa to 2.165 Pa (p < 0.05) with increasing MT time from 0 to 3 min.

Textural, rheological, melting properties, particle size distribution, and NMR relaxometry of cocoa hazelnut spread with inulin-stevia addition as sugar replacer.

This study investigated the influence of substituting 60, 80, and 100% of the sugar in traditional cocoa hazelnut paste (control) formulation with inulin-stevia (90:10, w/w) mixture on textural and rheological characteristics, melting behavior, water activity (aw), particle size distribution (PSD), and color. Textural, rheological, melting properties, and color of samples were analyzed after 1, 2, and 3 months of storage at 11°C. Nuclear magnetic resonance (NMR) relaxometry experiments were also performed to understand the interaction of new ingredients with oil. Replacement of sugar with inulin-stevia gave darker color, reduced Casson yield stress, and changed the textural parameters and melting profile of the samples depending on the level but did not create a remarkable effect on PSD and Casson plastic viscosity. Increasing inulin-stevia content yielded lower aw and higher T2a values indicating decreased mobility of water. Complete removal of sugar caused low spreadability. The results showed that an 80% replacement level yielded a product with similar textural parameters and fat-melting mouth feeling compared to control sample. Cocoa hazelnut spreads prepared with inulin and stevia showed good textural stability during storage.

Effect of different oleogelation mechanisms on physical properties and oxidative stability of macadamia oil-based oleogels and its application

In this study, macadamia oil-based oleogels were prepared with four low molecular weight oleogelators: beeswax (BW), monoglyceride stearate (MG), rice bran wax (RBW), and a mixture of γ-oryzanol and β-sitosterol (SO). The physicochemical properties of these oleogels were evaluated by polarized light microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, texture and rheological analysis. Results indicated that the van der Waals force and hydrogen bond interaction existed mainly in MG- and SO-based oleogels, while only van der Waals force interaction observed in RBW- and BW-based oleogels. SO-based oleogels presented superior hardness, oil binding ability and oxidative stability, attributed to the formation of strong polymer network structure. Additionally, all four oleogels demonstrated stable crystal structures and solid-state shear-thinning fluid behavior, with SO-based oleogels displaying higher viscosity. Meanwhile, the feasibility of oleogel as a substitute for cocoa butter (CB) was explored, found that all of oleogels proved effective substitutes for CB in chocolate preparation. The rheological parameters of the oleogel-based chocolates, except for 50%BW oleogel, fell within the range of Casson plastic viscosity and yield stress for chocolate, and exhibited excellent heat tolerance. The results provide a novel strategy for utilization of macadamia oil and the development of heat-resistant chocolate.

Vegan and sugar-substituted chocolates: assessing physicochemical characteristics by NMR relaxometry, rheology, and DSC

The main physicochemical characteristics of novel artisanal chocolates (both dark and milky) intended for vegan consumers or for those requiring assumption of fewer simple sugars, were analysed. Replacement of milk (with coconut copra, almonds, and soy protein isolates), and sucrose (with coconut sugars, stevia and erythritol, respectively) in dark chocolate, were accounted for by means of texture analysis, rheology, water activity, fatty acid composition, differential scanning calorimetry (DSC) and fast field cycling (FFC) nuclear magnetic resonance (NMR) relaxometry. The vegan sample (i.e., the milk-less one) showed lower values of hardness and adhesiveness as well as a larger peak in the melting behavior at the calorimetric evaluation (DSC). Moreover, the absence of milk resulted in the halving of the yield stress and a decrease in both the apparent and Casson’s viscosity. In the sample of chocolate with less sucrose, the peak temperatures measured at the DSC indicate crystallization of cocoa butter in its best form (Vβ2), unlike in dark chocolate, due to the different sugar composition. Similarly, the Casson yield stress (τ0), increased significantly (almost 70%), with the substitution of sugar. Finally, the results of NMR FFC relaxometry made it possible to identify aggregates of different sizes, laying the basis for its use as a rapid, non-destructive method for chocolate analysis.

Rapid and economic method to measure chocolate viscosity

AbstractThe objective of this research was to use simple and economic techniques to measure chocolate viscosity and compare the values with the ones obtained using a rheometer. Two techniques were used: (a) Zahn cup number 5, and (b) ring/spread test using a ring and a template with concentric circles (ring method). Seven chocolates with a wide range of viscosities were used: (a) three 70% dark chocolates; (b) 70% dark chocolate with 1% lecithin added; (c) 70% dark chocolate with 10% cocoa butter added; (d) a Swiss‐style milk chocolate; (e) a 50% milk chocolate. Results from this research showed that the viscosity obtained using the Zahn cups was positively correlated with the Casson plastic viscosity (r = 0.897; p = 0.016) while the values obtained using the ring/spread method were negatively correlated with the Casson yield stress (r = −0.916; p = 0.004) and the Casson plastic viscosity (r = −0.897; p = 0.007). These results are helpful for small producers of chocolate that need to quantify the viscosity of their product using simple and economic techniques.

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.

Cocoa Spread with Grape Seed Oil and Encapsulated Grape Seed Extract: Impact on Physical Properties, Sensory Characteristics and Polyphenol Content.

The aim of this study was to utilize grape pomace, as a polyphenol-rich by-product of wine production, in the manufacture of enriched cocoa spread. The formulation of the cocoa spread has been modified by substitution of refined sunflower oil with cold-pressed grape seed oil. The spread with grape seed oil (Cg) was further enriched with grape seed extract encapsulated on maltodextrins (E), where 10% and 15% of E was added to Cg obtaining the samples Cg10 and Cg15. The results showed an increase in volume-weighted mean in spread samples, from 19.17 μm in Cg to 19.71 μm in Cg10 and 21.04 μm in Cg15. Casson yield stress and Casson viscosity significantly (p ˂ 0.05) increased from 16.41 Pa and 1.58 Pa·s in Cg to 29.45 Pa and 5.70 Pa·s in Cg15 due to the reduction of the fat-phase content in enriched spreads. The addition of E had no significant effect on the melting temperature (Tpeak) of the enriched spreads, while increasing the amount of E significantly (p ˂ 0.05) increased their hardness. The incorporation of grape seed oil in the cocoa spread formulation contributed to an increase in total polyphenols and flavonoids. Moreover, the addition of 10% and 15% of E to Cg resulted in approximately 1.5× and 2× higher content of phenolic compounds in Cg10 and Cg15 compared to control spread with sunflower oil (Cs). Flavonoids increased from 0.43 mg CE/g in Cs to 0.74 mg CE/g in Cg 10 and 1.24 mg CE/g in Cg15. Encapsulates positively affected sensory characteristics of enriched spread samples by reducing their grape seed oil aroma and sweetness.

Incorporation of Rheological Characterization in Grinding and Tailings Slurries to Optimize the CMP Magnetic Separation Plant

Compañía Minera del Pacífico (CMP) is the main iron producer on the Pacific coast of the American continent. The Cerro Negro Norte (CNN) operation of CMP is facing important challenges, such as the processing of low-grade ores containing complex gangue minerals which negatively affect the performance of the magnetic separation, grinding and solid–liquid separation stages. CMP is working on a program, aimed at optimizing the efficiency of the CNN plant, which considers a rheological characterization of the slurries produced by the different ores treated, information which will be useful to optimize the performance of the physical separation processes. The objective of this work was to characterize the slurries obtained from the secondary grinding and tailings thickener stages through rheological measurements. The rheological data were correlated with the physical, chemical and mineralogical characteristics of the different geological units (GU) tested. The results show that the rheological flow curves of the slurries taken from the secondary grinding product display a pseudoplastic behavior which follows a Casson model pattern. An exponential model was used to correlate the Casson yield stresses with the solids content of the slurries taken from the secondary grinding product. The results of this fitting process indicate that the yield stresses increase with the % −325# Tyler mesh and with the percentage of minerals with a tendency to generate fines (MTF = smectite + illite/mica + talc + chlorite + kaolinite), and in contrast the yield stresses decrease with the ore iron grade (Fe). For the tailings characterization, the results of settling rates and turbidity values of the supernatant obtained from tests with different GU samples show no significant differences. A linear regression model was used to correlate the results of yield stresses of compacted tailings with the chemical and mineralogical characteristics of the GU. The results of the fitting process indicate that the MTF content in the head ore samples influence the rheological properties of the tailings, which correlates with the behavior of the secondary grinding product. The increase in the GU iron grades also reduced the Casson yield stress. The experimental results were explained in terms of the microrheological effects and the physicochemical properties of the different types of phyllosilicates existing in the ore samples tested in this work.

Rheological, bioactive properties and sensory preferences of dark chocolates with partial incorporation of Sacha Inchi (Plukenetia volubilis L.) oil

We studied the effect of substituting partially, cocoa butter (CB) with Sacha Inchi (Plukenetia volubilis L.) oil (SIO) on rheology, bioactive properties, and sensory preferences in potentially functional chocolate. For this 70% dark chocolates were prepared and the CB was substituted with 1.5%, 3%, and 4.5% of SIO. Hardness and viscosity of the SIO-chocolates were significantly reduced compared to the control (5451 ± 658 g; 17.01 ± 0.94 Pa s, respectively). Total phenolic content remained constant while the antioxidant capacity increased up to IC50 of 2.48 ± 0.10 as the content of SIO increased. The Casson yield stress and Casson plastic viscosity decreased as the amount of SIO increased. Chocolates with 4.5% SIO had a similar color, better glossiness, preferable snap attributes, and were more accepted (7.50 ± 0.08) compared to the control (p < 0.05), measured with a hedonic scale. Then, SIO can improve the bioactive properties of dark chocolates obtaining a potentially functional food with acceptable physicochemical characteristics. SIO can be considered as a new cocoa butter equivalent.

Are stirring and homogenisation processes capable of improving physicochemical and sensory characteristics of stirred yoghurt produced with fresh, refrigerated and frozen/thawed sheep milk?

The impacts of stirring and homogenisation processes on the physicochemical and sensory characteristics of stirred yoghurt produced from fresh, refrigerated and frozen/thawed sheep milk were studied. Yoghurt from frozen/thawed milk was more sensitive to post acidification and had a higher Casson yield stress than yoghurt from fresh milk. The main differences caused by stirring and homogenisation were observed in NIR backscattering and in rheological parameters of yoghurt from refrigerated and frozen/thawed milk (Casson yield stress reduced and Casson consistency index increased). These modifications, however, were not able to improve the low scores of sensory evaluation of yoghurt from frozen/thawed milk, probably penalised by their worst textures. Results suggest that sheep milk cold preservation, mainly freezing/thawing, negatively affects the characteristics of yoghurt; although some improvements in physicochemical parameters are observed after stirring and homogenisation, these were not enough to avoid poor sensory evaluation of the samples.

Rheological Characteristics of Waxy Rice Starch Modified by Carboxymethyl Cellulose.

The effects of carboxymethyl cellulose (CMC) at different concentrations (0, 0.2, 0.4, and 0.6% w/w) on the rheological properties of waxy rice starch (WRS) pastes were evaluated under both steady and dynamic shear conditions. The flow properties of WRS-CMC mixtures were determined from the rheological parameters of power law and Casson models. All samples demonstrated a clear trend of shear-thinning behavior (n=0.33~0.34), with a marginal difference shown between n values. The addition of CMC to WRS increased the apparent viscosity (ηa,100), consistency index, and Casson yield stress values. The dynamic moduli [storage modulus (G′), loss modulus (G″), and dynamic viscosity (η*)] and ratio of G″/G′ values of WRS-CMC mixtures also increased with an increase in CMC concentration; the higher dynamic rheological properties observed at higher CMC concentrations may be attributed to an increase in the viscoelasticity of the continuous phase in the starch-gum mixture system. Dependence of ηa,100 on temperature followed the Arrhenius model for all samples. The Cox-Merz rule was not applicable to WRS-CMC pastes with different CMC concentrations, demonstrating that there was a deviation between η* and steady shear viscosities for all samples. Therefore, the synergistic effect of CMC on the rheological properties of WRS pastes appeared to be the result of coacervation.

Promotion of whole blood rheology after vitamin C supplementation: focus on red blood cells 1.

Hemorheological properties represent significant contributors in the pathogenesis of cardiovascular diseases. As plasma vitamin C is inversely associated with blood viscosity in humans, we aimed to characterize the effect of vitamin C supplementation on hemorheology with an emphasis on erythrocyte functions. Twenty young healthy volunteers were asked to take vitamin C (1000 mg per day) for 3 weeks. We observed beneficial effect of intervention on multiple hemorheological parameters: whole blood viscosity in the range of medium to high shear rates, Casson yield stress, complex viscosity, and storage and loss moduli. As erythrocyte properties play a significant role in hemorheology, we characterized their deformability, nitric oxide production, and sodium pump activity in erythrocyte membranes. We can conclude that observed promotion in whole blood rheology may be consequence of improved erythrocyte functionality as concerns their ability to pass through narrow capillaries of the microcirculation, nitric oxide production, and sodium pump activity. Parameters reflecting oxidative stress and antioxidant status in plasma were not affected by our intervention. As improvement in hemorheology may play an important role in cardioprotection, it would be challenging to investigate the vitamin C supplementation to patients suffering from microcirculatory disturbances and worsened organ perfusion in the case of cardiovascular diseases.

Validation of rheological responses for morphological evaluation of incompatible polyamide 12/thermoplastic elastomer blends filled with nanoclay

The interrelationship between viscoelastic responses and multiphasic morphology in compatibilized PA 12/nanoclay/SBS nanocomposites has been investigated. Different effects of material parameters including nanoclay, SBS rubber and compatibilizer contents on the rheology and morphology correlations have been evaluated. The findings showed that the solid like and shear thinning behavior along with relaxation time and Casson yield stress intensify at higher contents of nanoclay and SBS rubber. By increasing the SBS level, smaller rubber particles with narrower size distribution were obtained that was in agreement with the rheological properties. Nonetheless, the incorporation of more nanoclay effectively resulted in finer matrix/dispersed morphology just in the presence of larger compatibilizer contents. Although m-SEBS influenced the biphasic morphology similar to common compatibilizers, the non-terminal behavior of the nanocomposites weakened at higher m-SEBS levels due to the stronger compatibilizer effect on the chain confinement in nanoclay galleries than the one on the PA12/SBS rubber interfacial adhesion.

Rheological, fat bloom, and sensory acceptability effects of mango kernel fat and palm olein blends on chocolate-flavored coatings

The effects of replacing cocoa butter with different percentages and proportions of a mango kernel fat/palm olein (MKF/POL) blend, are reported. Samples were prepared by melting together mango kernel fat, palm olein, cocoa butter and cocoa mass and powdered sugar combinated. The samples were milled, conched, tempered, and molded to obtain three sets of seven samples as follows: one control omitting mango kernel fat and palm olein, and six samples with cocoa butter replacement of 15 and 22.5% and MKF/POL ratios of 2.3, 4.0, and 9.0. Casson viscosity, Casson yield stress, fat bloom and sensory acceptability were all measured. In fact, all samples had achieved a low Casson viscosity (ηCA) and Casson yield stress (τ_oCA), which indicates molding and enrobing as appropriate uses. In addition, some significant differences (p ≤ 0.05) were found among samples. Fat bloom was accelerated in the samples relative to control, but high MKF proportions tended to retard appearance of fat bloom. No differences were observed in organoleptic properties between samples and control.

Influence of autologous blood transfusion in liver transplantation in patients with hepatitis B on the function and hemorheology of red blood cells.

The present study aimed to characterize the function and hemorheology of red blood cells (RBCs) recovered during liver transplantation surgery in patients with hepatitis B and decompensation. A total of 15 hepatitis B patients with decompensation who underwent liver transplantation surgery were included in the present study. Blood samples were recovered during the liver transplantation surgery using an Autologous Blood Recovery System. The morphology and structure of RBCs were characterized and compared between pre-operative and recovered blood samples. In addition, the physiological functions of RBCs were measured and compared between pre-operative and recovered blood samples. No significant differences in the morphological score, 2,3-diphosphoglycerate, Na+K+-ATPase, Ca2+-ATPase, Mg2+-ATPase, malondialdehyde and osmotic fragility were identified between RBCs in the pre-operative and recovered blood samples. The level of free hemoglobin in RBCs of the recovered blood samples was significantly higher than in the pre-operative blood samples (P<0.05). Medium- and high-shear blood viscosities in the recovered blood samples were significantly lower than those observed in the pre-operative blood samples (P<0.05). Casson viscosity in the recovered blood samples was significantly higher compared with the pre-operative blood samples. However, no significant differences (P>0.05) in the low-shear blood viscosity, plasma viscosity, relative blood viscosity, erythrocyte aggregation index or Casson yield stress were identified between recovered and pre-operative blood samples. These findings suggested that autologous blood transfusion in liver transplantation surgery in patients with hepatitis B and decompensation had no significant influence on the morphology, structure, function and hemorheology of RBCs.

Functionality of inulin and polydextrose as sucrose replacers in sugar‐free dark chocolate manufacture – effect of fat content and bulk mixture concentration on rheological, mechanical and melting properties

AbstractInulin and polydextrose are key bulk sugar replacers and have been utilised extensively as functional ingredients due to their fibre and prebiotic claims. This study investigated effects of fat content and bulk mixture concentrations of inulin and polydextrose on rheological properties, mechanical and melting characteristics of sugar‐free dark chocolates sweetened with steviol glycosides. Sucrose was replaced with polydextrose and inulin (0:100, 25:75, 50:50, 75:25, 100:0) at different fat contents (27%, 30% and 33%). Reducing fat content from 33% to 27% had similar effects on the sugar‐free dark chocolates as it did on reference chocolate. Increasing inulin concentrations with simultaneous reduction in polydextrose resulted in consistent increases in Casson plastic viscosity and decreases in Casson yield stress regardless of the fat content. These were explained by microstructural examination of the sugar replacers, which revealed wide variations in network structure. Understanding these factors would help reduce energy load from fat in sugar‐free chocolate confectionery.

Influence of enzymatically produced sunflower oil based cocoa butter equivalents on the phase behavior of cocoa butter and quality of dark chocolate

The two enzymatically produced sunflower oil based cocoa butter equivalents (CBEs) were blended with cocoa butter (CB) at varying concentrations (g/100 g). The peak maximum decreased significantly upon the addition more CBE due to the presence of the low-melting TAGs. However, the melting heat and the melting onset temperature were comparable to CB up to 25 g CBE/100 g blend. The iso-solid diagram showed monotectic behavior with softening effect proportional to CBE increase. A significant decrease in SFC was observed at all temperatures for the blends in which the CBE ratio was above 25 g/100 g blend. The second part of this study was set out to determine the performance of CBE replacement in chocolates and compounds at 20 °C. All the chocolates and compounds even in the level of 5 g CBE/100 g blend had significantly lower Casson yield stress than reference chocolate. However, the viscosity of the chocolate with 5 g HSHO CBE/100 g blend was comparable with the reference chocolate. Higher amounts of CBE slightly decreased the peak maximum however up to 5 g CBE/100 g blend, the melting behavior did not significantly change compared to the reference chocolate without CBE. The hardness of the reference chocolate was comparable with chocolate with 5 g CBE/100 g blend up to 2 weeks.

Rheological, thermal, and gelling properties of azuki bean starch with sucrose

Rheological, thermal, and gelling properties of 5% (w/w) Korean azuki bean starch (ABS)‐sucrose mixtures at different sucrose concentrations (0, 10, 20, and 30% w/w) were investigated. Flow properties of ABS‐sucrose mixtures were determined from rheological parameters for power law and Casson flow models. All mixture pastes exhibited a pseudoplastic shear‐thinning characteristic (n = 0.30–0.34) with yield stress. Consistency index (K), apparent viscosity (ηa,50), and Casson yield stress (σoc) values decreased with an increase in sucrose concentration. Dynamic moduli (G′ and G″) values of ABS‐sucrose mixtures increased with increasing sucrose concentration, indicating that their viscoelastic properties were greatly affected by the addition of sucrose. The addition of sucrose had little impact on tan δ (ratio of G″/G′) values. Differential scanning calorimetry of ABS‐sucrose mixtures showed an increase in the onset (To), peak (Tp), and conclusion (Tc) temperatures of gelatinization and a decrease in the enthalpy (ΔH) of gelatinization with a corresponding increase in sucrose concentration. The ABS‐sucrose mixture gels showed much lower gel strength values compared to the control (0% sucrose). In general, these results suggest that the presence of sucrose in ABS modifies physical and rheological properties, depending on the sucrose concentration. In addition, these results could facilitate the development of sweetened ABS‐based products with improved physical and rheological properties.

Rheological Properties of Milk Chocolates as Influenced by Milk Powder Type, Emulsifier, and Cocoa Butter Equivalent Additions

The research examines the influences of different emulsifiers (lecithin, CITREM LR10—both individually and combined with polyglycerol polyricinoleate, and CITREM 2in1) and cocoa butter equivalent additions on the rheological properties of milk chocolates produced using spray or roller-dried milk. The substitution of lecithin with other emulsifiers caused an increase in the Casson plastic viscosity (μCA), as well as a decrease in the Casson yield stress (τCA) in milk chocolates containing roller-dried milk powder, whereby the lecithin-polyglycerol polyricinoleate blend had the most pronounced influence. Cocoa butter equivalent addition resulted in the highest μCA when CITREM LR10 was used, and the lowest τCA with lecithin-polyglycerol polyricinoleate blend. When spray-dried milk was used, the highest μCA was determined in the sample containing CITREM LR10 and the lowest τCA in the sample containing the lecithin-polyglycerol polyricinoleate blend. Cocoa butter equivalent addition resulted in an increase in the τCA---except when CITREM LR10-polyglycerol polyricinoleate blend was used as emulsifier.