Sucrose‐free chocolate sweetened with Stevia rebaudiana extract and containing different bulking agents – effects on physicochemical and sensory properties

Sucrose‐free milk chocolates sweetened with Stevia and containing different types of commercial inulin or polydextrose as bulking agents, were examined in relation to their physico‐chemical, rheological and sensory properties. Compared with chocolate sweetened with sucrose, noticeable differences in lightness (L* values) were observed for sucrose‐free chocolates and attributed to changes in surface roughness. Chocolate containing inulin with a higher degree of polymerisation (DP) had higher melting points, greater plastic viscosity and an increased flow behaviour index. The Herschel‐Bulkley mathematical model most closely fitted to the rheological data. Chocolate containing the highest DP inulin was found to be very similar to control in tested sensory attributes (appearance, firmness, smoothness, mouth feel, flavour/taste and overall acceptance) when assessed by a consumer panel. These data indicate that it is possible to manufacture sucrose‐free chocolate using high DP inulin without adversely affecting its important physico‐chemical properties and sensory acceptance.     

Bittersweet chocolates containing prebiotic and sweetened with stevia (Stevia rebaudiana Bertoni) with different Rebaudioside A contents: multiple time–intensity analysis and physicochemical characteristics

The objective of this study was to evaluate the time–intensity profile of the sensory attributes possibly affected in sugar‐free and low‐fat chocolates containing inulin and stevia with different rebaudioside A contents, such as sweetness, bitterness and melting rate. The bittersweet chocolates were analysed by the multiple time–intensity analysis. The time–intensity profile for the sweetness stimulus was similar for all chocolate samples. The differences between the contents of rebaudioside A were not perceived by the assessors. In relation to the bitterness stimulus, the low‐fat samples had a more accentuated perception of this attribute by the assessors, with significant differences for Imax and Area when compared to the sugar‐free samples. The stimulus melting in the mouth was more affected in the low‐fat samples. The sensory results obtained in this study are useful for food industry and researchers working with sweeteners and prebiotics in food, especially in chocolates.     

Effect of cocoa butter replacement with a β‐glucan‐rich hydrocolloid (C‐trim30) on the rheological and tribological properties of chocolates

BACKGROUND: The food industry has been facing the challenge of developing low‐fat and low‐calorie food products due to rising health awareness of consumers. To meet this consumer demand, an oat β‐glucan‐rich hydrocolloid (C‐trim30) was evaluated as a cocoa butter substitute in chocolates. The effects of C‐trim30 on the rheological, tribological, and textural properties of chocolates were investigated. RESULTS: The viscosity of molten chocolates increased with increasing levels of C‐trim30. Flow behaviors analyzed using the Casson model showed that the Casson viscosity and yield stress increased with increasing concentration of C‐trim30 in the chocolate. Tribological tests on a ball‐on‐flat tribometer showed a reduction in boundary coefficients of friction, with increasing C‐trim30. In addition, hardness of chocolates showed that replacement of cocoa butter with C‐trim30 produced chocolates with softer texture. CONCLUSIONS: The cocoa butter replacement with C‐trim30 up to 10% produced soft chocolates with improved boundary lubrication properties. Also, the chocolate prepared by replacing the cocoa butter with C‐trim30 resulted in a product with a lower caloric value and increased health benefits from the oat β‐glucan. Copyright © 2008 Society of Chemical Industry     

EFFECTS OF INULIN AND BULKING AGENTS ON SOME PHYSICOCHEMICAL, TEXTURAL AND SENSORY PROPERTIES OF MILK CHOCOLATE

Chocolates are favorite foodstuffs with high sugar contents. Therefore, in the present study, the production of a low-sugar milk chocolate with prebiotic properties is evaluated. Various ratios of inulin (IN), polydextrose (PD) and maltodextrin (MD) along with sucralose (0.04% w/w) were used instead of sugar. Fifteen formulations were examined to determine some physicochemical, mechanical and sensory properties in order to find their optimum ratios. In general, formulations with high ratios of PD and MD were moister and softer than control. The lowest moisture content and highest hardness were observed for the moderate ratios. In addition, MD induced the least desirable sensorial effects, whereas PD and IN pronouncedly improved the overall acceptability. The optimum applicable range for IN, PD and MD were 14–32% and 71–84%, 7–26% and 67–77%, and 0–20% of sugar substitutes, respectively. Our findings on simultaneous fat and sugar reductions also indicated the possibility of fat cut up to 5% in comparison to previous fat content.

PRACTICAL APPLICATIONS

In this paper, we have reported the influences of inulin (IN) as a prebiotic as well as polydextrose (PD) and maltodextrin (MD) as bulking agents on physicochemical, energy content, texture and sensory properties of milk chocolate using simplex lattice mixture design. To the best of our knowledge, this is the first report in this field with very interesting results and practical applicability. Moreover, our findings showed that the use of aforementioned ingredients instead of sugar could lead to production of low-calorie milk chocolate without having the undesirable textural and physiological effects on the product and consumers. Moreover, the simplex lattice mixture design was found a very useful technique for finding optimum ratios of sugar replacers in formulation.     

Effects of selected properties of ultrafiltered spray-dried milk powders on some properties of chocolate

The effects of selected properties of spray-dried milk fat powders on chocolate were determined. Milk powders produced from control or ultrafiltered (UF) milks with various levels of fat were blended with skim milk powder to give a standard 26 g fat 100 g⁻¹ powder. Particle size of the chocolate mixes after refining decreased as the fat content and free-fat content of the powders increased. Despite this, increasing fat and free-fat contents of powders reduced the Casson viscosity of the subsequent molten chocolates. Casson viscosities using powders from control or UF milks were similar, but decreased as the particle size of powders increased and particle size after refining the chocolate mix decreased. Casson yield value and hardness decreased as fat content of powders increased. Casson yield value increased with vacuole volume of powders. It is possible to alter important properties of chocolates using milk powders of varying fat contents, free-fat contents and particle sizes.     

Effects of fat replacement and fibre addition on the texture,sensory acceptance and structure of sucrose‐free chocolate

Dietary fibre has been employed as a sucrose and fat replacement in chocolates and can influence the physical and sensory characteristics of the resulting product. Formulations of sucrose‐free chocolates were developed with the addition of inulin and β‐glucan concentrate as partial substitutes for cocoa butter using a mixture design. The effects of the combinations of the three ingredients provided for the design on the texture, microstructure and sensory acceptance of the chocolates were investigated. The substitution of cocoa butter for inulin or β‐glucan concentrate decreased the hardness of the chocolates. It was possible to replace 10 g of cocoa butter in a 100‐g control formulation with inulin and still maintain good acceptance, while this same substitution with β‐glucan resulted in less acceptable chocolate, with a mean score of 6.4 on a scale from 0 to 10. Scanning electron microscopy (SEM) was used to investigate the effects of fibre addition by observing the developed microstructure.     

The Influence of the Rebaudioside A Content of Stevia (Stevia rebaudiana Bertoni) on the Determination of Sweetness Equivalence in Bittersweet Chocolates,Using the Time‐Intensity Analysis

The consumption of diet products has increased greatly in recent years. The objectives of the study were to develop a bittersweet chocolate added inulin and stevias with different rebaudioside A contents (60%, 80%, and 97%). Five chocolate samples were formulated with different sucrose concentrations to determine the ideal sucrose concentration for bittersweet chocolate. The use of just‐about‐right scale identified an ideal sucrose concentration of 47.5% (w/w). The sweetness equivalence in sugar‐free bittersweet chocolates was determined by the time–intensity method by 14 selected and trained judges. The data collected during each session of sensory evaluation furnished the following parameters in relation to the sweet stimulus: Imax (maximum intensity recorded), Timax (time at which the maximum intensity was recorded), Area (area of time × intensity curve), and Ttot (total duration time of the stimulus). The time–intensity analysis indicated that the percentages of rebaudioside A did not interfere with the sweetness intensity of the sweetener stevia in bittersweet chocolate and there was no significant difference in the concentrations tested (0.16%, 0.22%, 0.27%) of each stevia, in relation to the parameters evaluated. In addition, the reduction in fat content did not alter the perception of the sweetness intensity of the samples. These results showed important information to research and development of chocolate products. Therefore, the use of the lowest stevia concentration tested (0.16%) is the most indicated for use, since this quantity was sufficient to reach the ideal sweetness of the product, so there was no point in adding more.     

The role of particle size distribution of suspended solids in defining the flow properties of milk chocolate

The flow characteristics of molten milk chocolate, like most dense suspensions, are a function of the maximum packing fraction ((_m) of the suspended solids. Milk chocolates were prepared from mixtures of two relatively narrow coarse (d_4,3 = 17 μm) and fine (d₄,₃ = 8.5 μm) size distributions of non‐fat solids to contain 0, 25, 50, 75, and 100% of the coarse component. Solids bed density (a measure of maximum packing fraction) correlated with the apparent viscosity of milk chocolates (r = ‐0.98). The highest value for solids bed density and lowest value for apparent viscosity were measured for size distributions with 75% of solids from the coarse fraction. Casson yield value correlated with d_4,3 (r = ‐0.98) and specific surface area (r = 0.93). The maximum packing fraction of binary mixtures of two distinct sizes of non‐fat chocolate solids attained a maximum value for a specific volume ratio of the components. The maximum in _m corresponded with the minimum viscosity in molten chocolate at a given solids volume concentration.     

EQUISWEET MILK CHOCOLATES WITH INTENSE SWEETENERS USING TIME-INTENSITY METHOD

ABSTRACT

Five conventional chocolates were produced with different sucrose concentrations (from 40 to 52%) in order to determine ideal sweetness by acceptance test, and it was found that 43% sucrose milk chocolate has the ideal sweetness. Sucrose was replaced by bulking agents and sucralose or stevioside in order to prepare diabetic chocolates and 11 selected and trained judges determined the temporal characteristic of sweetness of these milk chocolates. Sucralose is 700 times sweeter than sucrose in this product, and stevioside, 200 times. Considering these potencies, they presented a time‐intensity profile similar to chocolate with sucrose (i.e., conventional chocolate) and ideal sweetness. There is no significant difference between diabetic and conventional chocolates concerning the following physicochemical analyses: moisture content, medium particle size and Casson yield value.

PRACTICAL APPLICATIONS

The time‐intensity method is becoming a useful tool because it makes it possible to compare perception over time of sucrose sweetness with that of other sweeteners. The key point of this study is to consider temporal sweetness characteristics to produce equisweet diabetic milk chocolates. The sensory analysis time‐intensity method probably is a tool to obtain diabetic (i.e., with no sugar) chocolates that present a sweetness temporal profile as near as possible to conventional milk chocolate. This is a first step to produce diabetic chocolate with the same acceptance as conventional chocolate.

     

Microstructure and mechanical properties related to particle size distribution and composition in dark chocolate

Composition in dark chocolate was varied and the effects determined on microstructure, using light microscopy, and mechanical properties of molten and tempered chocolates, using a TA.HD Plus Texture Analyser. Compositional parameters were particle size distribution (PSD) (D₉₀ of 18, 25, 35 and 50 μm), fat (25%, 30% and 35%) and lecithin (0.3% and 0.5%) contents. Micrographs revealed wide variations in sugar crystalline network structure and inter-particle interaction strengths related to PSD and fat level. Samples containing 25% fat had more crystal agglomerates, well flocculated with greater particle-to-particle interaction strengths than those with higher (30% and 35%) fat contents. Increasing the D₉₀ to 35–50 μm caused broadening of the PSD, with particles becoming coarser, which were similar at all fat levels. Mechanical analysis showed that PSD, fat and lecithin content significantly influenced firmness of molten chocolate and hardness of solid (tempered) chocolate with significant interactions among factors. Particle size was inversely correlated with firmness (1235–173 g) and hardness (7062–5546 g). Greatest effect of PSD was with 25% fat and 0.3% lecithin. With higher fat and lecithin contents, the PSD influence was reduced. It was concluded that PSD, fat and lecithin contents and their interactions were central to mechanical properties of dark chocolates.     

Effects of particle size distribution and composition on rheological properties of dark chocolate

Control of chocolate viscosity is vital to its quality and production cost, and directly influenced by solids particle size distribution (PSD) and composition. Effects of PSD and composition on rheological properties of molten dark chocolate were investigated by varying PSD [D₉₀ (90% finer than this size) of 18, 25, 35 and 50 μm], fat 25, 30 and 35% and lecithin (0.3 and 0.5%) using a shear rate-controlled rheometer. PSD, fat and lecithin content significantly affected all rheological parameters, with significant interaction among factors. Increasing particles size gave significant reductions in Casson plastic viscosity, Casson yield value, yield stress, apparent viscosity and thixotropy, with greatest effect with 25% fat and 0.3% lecithin, which reduced with increasing fat and lecithin contents. Statistical analysis revealed that fat exerts the greatest effect on the variability in all the rheological properties followed by PSD and lecithin. PSD, fat and lecithin could be manipulated to control dark chocolate rheology, influencing quality whilst reducing production cost.     

Dark chocolates supplemented with <Emphasis Type="Italic">Lactobacillus</Emphasis> strains

Dark chocolate masses and chocolates were supplemented with viable cells of two bacterial strains Lactobacillus caseii and Lactobacillus paracasei with potential probiotic properties, which were lyophilized in milk. Total number of live bacteria in the lyophilizate was 7.9×10⁹ cfu/g. Sucrose or isomalt and aspartame were used as bulking substances and sweeteners. Sensory attributes of these chocolates were not different from that of traditional chocolates. Calorie value of sucrose-free chocolate was lower by approximately 11.1–14.6% (dependent on their formulation) relative to chocolate sweetened with sucrose. Chocolate, which contains isomalt and aspartame can be consumed by diabetics. Numbers of live L. casei and L. paracasei cells in the examined batches of chocolate were very high and approached 10⁶–10⁷ cfu/g after 12 months of keeping at 4 and 18 °C. Neither the texture nor the total and volatile acidity of chocolate masses were changed by addition of the lyophilized preparation of Lactobacillus cells. Casson yield values of dark sucrose-free chocolate masses supplemented with this lyophilizate were decreased by approximately 3–55% (dependently on fat contents in these masses) as compared to that of analogous chocolate masses sweetened with sucrose.     

Comparison of rheological models for determining dark chocolate viscosity

Parameters in chocolate rheology, namely shear viscosity and yield stress, are important in manufacture and directly influenced by product particle size distribution (PSD) and composition. The Casson model was the standard confectionery industry strategy to quantify rheological properties of molten chocolate until in 2000, the International Confectionery Association recommended the use of interpolation data to describe viscosity. The two strategies are compared and correlated in defining rheological properties of molten dark chocolates prepared using different PSD, fat and lecithin content. Rheological parameters were determined using a shear rate-controlled rheometer and data examined using correlation, regression and principal component analyses to establish their inter-relationships. Correlation and regression analyses showed high correlation ( r  = 0.89–1.00) and regression coefficients ( R ² = 0.84–1.00). The newer International Confectionery Association technique gave higher correlation and regression coefficients than the Casson model, but multivariate principal component analysis showed that the two models were highly related and either could effectively quantify dark chocolate viscosity parameters.     

Development and application of confocal scanning laser microscopy methods for studying the distribution of fat and protein in selected dairy products.

Confocal scanning laser microscopy (CSLM) methods were developed to identify fat and protein in cheeses milk chocolate and milk powders. Various fluorescent probes were assessed for their ability to label fat or protein in selected food products in situ. Dual labelling of fat and protein was made possible by using mixtures of probes. Selected probes and probe mixtures were then used to study (a) structure development of Mozzarella cheese during manufacture and ripening, and (b)) the distribution of fat and protein in milk chocolate made with milk powders containing varying levels of free fat. Microstructural changes in the protein and fat phases of Mozzarella cheese were observed at each major step in processing. Aggregation of renneted micelles occurred during curd formation; this was followed by amalgamation of the para-casein into linear fibres during plasticization. Following storage, the protein phase of the Mozzarella became more continuous; entrapping and isolating fat globules. Chocolate made with a high free-fat spray-dried powder blend showed a homogeneous fat distribution, similar to that of chocolate made with roller-dried milk. Chocolate made with whole milk powder containing 10 g free fat/100 fat showed a non-homogeneous fat distribution with some fat occluded within milk protein particles. These differences in fat distribution were related to Casson yield value and Casson viscosity of the chocolates.     

Monitoring Tempered Dark Chocolate Using Ultrasonic Spectrometry

Ultrasonic spectrometry was used to distinguish between properly tempered and untempered commercial dark chocolate. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to characterize the polymorphic state of tempered and untempered chocolate, results that were correlated to those of ultrasonic spectrometry. Four different kinds of dark chocolate samples with different amounts of sugar (7.5–50 %), fat (30–50 %), and cocoa mass (70–90 %) were subjected to two different tempering protocols. The tempering was achieved using cocoa butter seeds under static cooling from 50 to 14 °C. The ultrasonic generator and analyzer SIA-7 (V.N. Instruments) was used to monitor the crystallization process. The instrument generated a chirp signal with a bandwidth of 0.5 to 3 MHz and was set to work in a four-pathway configuration with two transducers and a center frequency of 2.25 MHz. Spectrometric analysis was carried out with chocolate samples containing 2, 4, and 6 % solid fat content (SFC). The SFC was obtained from DSC measurements. Ultrasonic signals for attenuation, reflection, and velocity were compared between tempered and untempered chocolates. It was shown that seed-tempered chocolate with 30 % sugar and 47.5 % fat attenuated 2.5 MHz of ultrasonic waves by 0.8, 1.7, and 2.0 dB/cm at 2, 4, and 6 % SFC, respectively. On the other hand, untempered chocolate attenuated the ultrasound signal by 3.5, 3.6, and 4.3 dB/cm. Furthermore, it was found that ultrasound reflection signals were stronger and ultrasonic velocity was higher in chocolates with high sugar content.     

Physical characterization of low-calorie chocolate formulations

Development of a high-quality low-calorie chocolate needs the use of the most appropriate ingredients that could substitute sugar without negatively affecting several product properties. In this study, sucrose-reduced chocolates sweetened with sucralose and stevia by using bulking agents were investigated in relation to their rheological, textural and sensory attributes. Dark, milk and white chocolates with different amounts of sweeteners were formulated. The Casson model best fitted to the rheological data. In dark chocolates, partial substitution of sucrose with stevia (DCSSt) gave similar plastic viscosity and yield stress values with control samples (DCS). Hardness measurements also supported these results. DCSSt sample was again found to be very similar to control in tested sensory attributes when assessed by a consumer panel. The data indicated that it was possible to manufacture chocolate by partial replacement of sucrose with stevia without adversely affecting its important rheological, textural properties and sensory acceptance.     

Development of formulations for reduced‐sugar and sugar‐free agar‐based fruit jellies

Because of the increasing consumer awareness of health‐related issues, there is a rising demand for noncariogenic, reduced‐energy confectionery products. This study was carried out to develop formulations for reduced‐sugar and sugar‐free, agar‐based jelly products. This was obtained by substituting sucrose and glucose syrup through a combination of sugar replacers, fibre, gelling agents and sweeteners. The application of a combination of polydextrose, oligofructose, sucralose and erythritol resulted in a sensory sweetness profile that was comparable to that of a sugar‐containing standard product. Concerning texture and sensory properties, reduced‐sugar and sugar‐free jellies processed using the respective formulations were comparable to the sugar‐containing standard products. Consumer evaluation using the Just‐about‐right technique exhibited satisfactory acceptance of the sugar‐free jellies.     

Structural characteristics of cocoa particles and their effect on the viscosity of reduced fat chocolate

Aimed at the manufacture of reduced fat chocolates, a novel method of trapped fat reduction was assessed: Manipulation of the cocoa ingredient. Cocoa mass was replaced with cocoa powder (11 g/100 g or <1 g/100 g fat) and added ‘free’ cocoa butter. A cocoa solids approach to design reduced fat chocolates with satisfactory flow properties is attractive to industry since it circumvents introduction of ingredients not commonly used in chocolate manufacture. Results showed that the cocoa mass chocolate had a higher viscosity than cocoa powder chocolates of the same total fat content due to the presence of trapped fat globules as identified by confocal laser scanning microscopy. The chocolate prepared with standard defatted cocoa powder containing 11 g/100 g fat had a lower viscosity than the chocolate containing highly defatted cocoa powder (<1 g/100 g) due to particle shape and fat diffusion into the particles as revealed by microscopy analyses. Based on the evidence presented, it can be concluded that standard defatted cocoa powder, as widely used by the industry, is indeed the best compromise in terms of free fat, particle size and morphology attempting to formulate fat reduced chocolate of acceptable molten state viscosity.     

Effect of lecithin concentration on properties of sucrose-free chocolate masses sweetened with isomalt

Rheological properties such as Casson viscosity and yield value strongly affect costs and efficiency of the chocolate making process. The addition of a proper amount of lecithin to the blend of chocolate ingredients results in a decrease of both the aforementioned parameters. However, overdosing of lecithin leads to worse sensory attributes and flow properties of the chocolate mass. Our studies on rheological properties of isomalt-containing dark chocolate masses and sucrose-containing milk chocolate masses revealed that the critical lecithin concentration was 0.9 g/100 g; and the Casson yield value of both the types of chocolate blends was enhanced above this content. The same phenomenon, i.e. chocolate thickening, was observed at lecithin concentrations of 0.4 g/100 g and 0.6 g/100 g for milk chocolate masses sweetened with isomalt, and for dark chocolate masses sweetened with sucrose, respectively.     

The broader usage of sugars and fillers in milk chocolate made possible by the new EC cocoa directive

The European Community directive 2000/36/EC now allows the addition of any sugar to chocolate and also adding up to 40% (w/w) of any foodstuff. Milk chocolates with lactose‐replacing sucrose and also with added fillers were tested for physical and sensory properties. Helianthus tuberosus flour, pea and oat fibres made the taste of the chocolate unacceptable. The addition of cellulose and wheat fibre at low dosages resulted in tolerable flavour; however, fat absorption of fibres caused worse flow properties and toughness made particle sizes to increase. Sugar beet fibres introduced bitter and cereal notes. The three products mentioned above would be useable only after modifications to the upstream process. Lupin gave a higher yield value because of its lecithin content but otherwise showed positive impact and could be used to supplement milk ingredients after adjustments to the recipe. As inulin improved the flow and sensory characteristics, it could be recommended both for its physical and nutritional properties. Lactose was not detectable up to 20%, but had some negative effects at higher levels in a low‐fat formulation and could require refining modifications. Further development seems worthwhile.