Effect of cocoa butter structure on oil migration

Oil migration from a high oil content filling into adjacent chocolate causes changes in product quality. The objective of this study was to quantify the oil migration from a cream filling system into cocoa butter, which provided a model for the behavior of chocolate-enrobed confectionery products with a soft, creamy center. Magnetic resonance imaging (MRI) was used to monitor spatial and temporal changes of liquid lipid content. A multislice spin echo pulse sequence was used to acquire images with a 7.8 ms echo time and a 200 ms repetition time using a 1.03 T Aspect Imaging MRI spectrometer. Samples were prepared as a 2-layer model system of cocoa butter and model cream filling. Three methods were used to prepare the cocoa butter: static, seeded, and sheared. Samples were stored at 25 °C for a time frame of 56 d. The rate of oil migration was quantified by a kinetic expression based on the linear dependence of oil uptake by cocoa butter and the square root of the time. Samples showed distinctly different rates of oil migration, as evidenced by quantitative differences in the kinetic rate constant. Practical Application: This work will be helpful to elucidate the influence of crystallization process and structural properties such as crystal nanostructure and crystal habit on the migration of oil through a crystalline fat matrix.     

Oil migration in hazelnut paste/chocolate systems using magnetic resonance imaging

Oil migration in confectionery products results in undesired quality changes of confections such as fat bloom. Oil migration and the resulting bloom formation in chocolate could be an important quality defect in a confectionery product. This study addressed to evaluate mass transfer of liquid oil on two-layer chocolate model systems prepared from hazelnut paste over different dark chocolate formulations by utilizing magnetic resonance imaging (MRI). Through the use of MRI, it becomes easier to predict the rate of migration and the effect of different ingredients on bloom formation. For five chocolate formulations stored at 30 °C over a time frame of 22 days, experimental data acquired through MRI were modeled using a Fickian-based mathematical model to calculate diffusion coefficient (D). Using two different equations for boundary condition at upper chocolate surface, two models were evaluated and logistic type boundary model was shown to fit exhibit a better fit. In addition, associated constants (C₀, β, t₀) for time dependent upper boundary conditions were determined. Average diffusivities of all samples varied in the order of 10^?11 m²/s. This study addressed the potential use of MRI for visualization and quantification of migration for different chocolate formulations.     

Modeling oil migration in two-layer chocolate–almond confectionery products

Migration of oil from high oil content fillings into the surrounding chocolate coatings results in product quality changes of filled confections. The objective of this study was to evaluate the mass transfer of liquid oil in two-layer model confectionery samples prepared from four almond products and dark chocolate. Experimental data were acquired using magnetic resonance imaging (MRI). The spatial and temporal experimental data of the liquid oil signal of the almond product and chocolate were modeled using a Fickian diffusion model. Solutions to the diffusion model were derived using both Laplace transform analytical solution and a finite difference numerical solution. For both methods, the boundary condition between the two layers incorporated a partition coefficient. MatLab’s nlinfit routine coupled with the diffusion equation solution provided estimates of the diffusion coefficients, D_a (almond products) and D_c (chocolate), and the partition coefficient. The diffusion coefficient values for the chocolate region ranged between 3 × 10⁻¹¹ m²/s and 6 × 10⁻¹¹ m²/s; the diffusion coefficient values for the almond products were an order of magnitude greater than that of chocolate.     

Kinetics of the migration of lipids in composite chocolate measured by magnetic resonance imaging

Migration of hazelnut oil into chocolate was followed non-invasively by magnetic resonance imaging, using a spin echo pulse sequence to acquire images with a 5 ms echo time and a 2000 ms repetition time. A calibration curve was used to correlate the image intensity with the concentration of hazelnut oil. Two different degrees of chocolate temper, at three different storage temperatures (20, 23 and 28°C), were monitored over a period of 80 days. The effect of thermal treatment (24 h at 30°C followed by 24 h at 4°C) on the speed of migration of hazelnut oil was also studied. Qualitative analysis yielded the spatial resolution of the oil migration data, whereas quantitative analysis gave the oil diffusion constants.     

Visualisation of Liquid Triacylglycerol Migration in Chocolate by Magnetic Resonance Imaging

This study has demonstrated that magnetic resonance imaging can be used to visualise the migration of liquid triacylglycerols in composite chocolate confectionery. Migration was observed between a layer of hazelnut oil filling (oil+icing sugar) and a layer of dark chocolate used as a model of composite chocolate confectionery products. In addition, low-resolution nuclear magnetic resonance measurements of the solid fat content (%) were also made. Substantial differences were observed between the migration profiles at 19 and 28°C, and in the distribution of liquid triacylglycerols across the chocolate layer after migration. It is suggested that the mechanism of migration involves both diffusion of the liquid triacylglycerols and capillary attraction of the hazelnut oil into the chocolate matrix. © 1997 SCI.     

Oil Migration in Chocolate–Peanut Butter Paste Confectionery as a Function of Chocolate Formulation

ABSTRACT:  Migration of oil from high oil content filling to the chocolate coating can result in undesirable quality changes in filled chocolate confectionery products. The objective of this study was to monitor and model peanut oil migration in a 2-layer chocolate–peanut butter paste model confectionery. Spatial and temporal oil content changes were evaluated using magnetic resonance imaging. Five formulations of chocolate, which varied in chocolate particle size, milk fat content, and emulsifier level, were assessed at 2 temperatures, 20 and 30 °C. The spatial and temporal experimental data were modeled using a Fickian-based diffusion model, fitting for the diffusion coefficient, D , over a time frame of 17 d. Values of the diffusion coefficient ranged from 1.82 to 3.23 × 10⁻¹¹ m²/s for the chocolate formulations stored at 30 °C. No significant mass transfer took place in the 20 °C samples over the experimental time frame. This study describes the dynamic nature of the interface between the chocolate and peanut butter paste layers, quantifies the mass transfer from the peanut butter paste to the chocolate, and reinforces the importance of temperature control.     

Oil Migration in a Chocolate Confectionery System Evaluated by Magnetic Resonance Imaging

ABSTRACT: Oil migration is a common problem in composite chocolate confectionery products resulting in softening of chocolate and hardening of the filling. Spatial and temporal changes in the liquid oil content of a 2-layer peanut butter and chocolate model system were evaluated using a magnetic resonance imaging (MRI) technique. The experimental factors were chocolate particle size, milk fat content, emulsifier concentration, degree of temper, and storage temperature. The responses were migration rate and overall change in signal intensity (amount of migration). Based on analysis of variance (ANOVA), particle size, milk fat content, and storage temperature were significant factors for oil migration rates. Milk fat content and temperature were significant factors for overall change in signal intensity.     

Spatial mapping of solid and liquid lipid in confectionery products using a 1D centric SPRITE MRI technique

Oil migration is responsible for the poor keeping qualities of composite confectionery products. Quality defects arising from oil migration include softening of the coating, hardening of the filling, deterioration in sensory quality and a greater tendency toward fat bloom formation. For this reason, oil migration has been extensively studied, and yet a clear understanding of the oil migration mechanisms still remains a challenge.Traditional MRI techniques are unable to acquire images from the solid lipid in chocolate. In this paper we employ a newly developed one-dimensional, centric-scan MRI technique to acquire images from the short lived signal components from the solid lipid, as well as the longer timescale components of the liquid lipid in a chocolate sample. We present one-dimensional images of a dynamic hazelnut oil absorption experiment, and one-dimensional solid and liquid distribution maps in a 5 mm thick chocolate sample in which oil migration occurs.     

Oil Migration in 2-Component Confectionery Systems

ABSTRACT:  Oil migration from high oil content centers into chocolate coatings results in product quality changes. The objective of this study was to monitor and model peanut oil migration in 2-layer systems of increasing phase complexity. Three 2-layer systems were prepared: peanut oil/cocoa butter; peanut butter paste/cocoa butter; and peanut butter paste/chocolate. Magnetic resonance imaging was used to measure liquid oil signal as a function of position over a storage time of 193 days at 25 °C. The 3 types of samples exhibited appreciably different patterns of oil migration. The peanut oil/cocoa butter samples had mass transfer typical of oil being absorbed into a liquid/solid region. The peanut butter paste/cocoa butter magnetic resonance profiles were characterized by mass transfer with a partition coefficient greater than unity. The peanut butter paste/chocolate samples exhibited a time-dependent peanut oil concentration at the interface between the chocolate and peanut butter paste. The spatial and temporal experimental data of the peanut butter paste/chocolate samples were modeled using a Fickian diffusion model, fitting for the effective diffusivity. Values of the diffusivity for the 6 chocolate formulations ranged from 1.10 to 2.01 × 10⁻¹³ m²/s, with no statistically significant differences.     

Measurement by MRI of storage changes in commercial chocolate confectionery products

Storage of chocolate confectionery products was monitored non-invasively by Magnetic Resonance Imaging. Using a Carr–Purcell–Meiboom–Gill–(CPMG) sequence, 20 echo images (first echo 5 ms, subsequent echo every 5 ms) were acquired with a 2 s repetition time in a total 8-min scan time. Images were processed to give spatial maps of the proton density (M₀) and the transverse relaxation times (T₂-values) within the samples. In every case the T₂-values were successfully used to follow the migration of lipids from the fillings into the chocolate. The MR images also provided spatial information on the lipid migration.     

中国国际甜食及休闲食品生产技术展览会受到多家国际知名原料和设备供应商亲睐

<正> 中国国际甜食及休闲食品生产技术展览会继2007年成功首展后,2008年9月3日至5日将继续在上海浦东新国际博览中心举办。与其展品形成上下游产业关系的中国国际甜食及休闲食品展览会仍将同期举行,为中国糖果、巧克力及休闲食品的原料、设备及生产包装企业和广大批发商、零售商搭建贸易大平台。     

The role of nonfat ingredients on confectionery fat crystallization

Confections such as chocolate and biscuit fillings are composed of a continuous fat phase that contains dispersed nonfat ingredients such as sugar and cocoa powder. Research on fat crystallization and rheology in confections often extrapolates crystallization and textural properties from bulk to mixed systems while overlooking the important role of composition or particle interactions. For example, in chocolate processing the fat phase aids dispersed phase lubrication and fluidity whereas the dispersed particles assist in fat crystallization by providing many nucleation sites. In confections with a high dispersed phase volume fraction, fat crystallization may be hindered due to reduced triacyglycerol mobility, confinement, and increased tortuosity. This is further complicated in systems with slow crystallizing fats such as palm oil whose crystallization is exceptionally sensitive to composition and processing. This review breaks down the physical chemistry of fat-based confections and discusses the impact of different nonfat ingredients towards fat crystallization and rheology. The behavior of palm oil is further highlighted as it is becoming increasingly popular as a confectionery ingredient. Lastly, ingredient-ingredient interactions and their role in fat crystallization are described along with force spectroscopy as a novel tool to characterize such phenomena. Force spectroscopy utilizes atomic force microscopy to measure intermolecular forces as a function of distance but remains largely unexplored in the area of food science.     

Chocolate Swelling during Storage Caused by Fat or Moisture Migration

Abstract: Quantification of swelling in dark chocolate subjected to fat or moisture migration was conducted using a new method based on confocal chromatic displacement sensor. The nondestructive method allowed for the height profile of dark chocolate samples to be scanned with a sensitivity of ± 2.8 μm. By performing multiple scans on each sample prior to and after being subjected to fat or moisture migration, the induced swelling could be quantified. Applying the new method on confectionery systems revealed that fat and moisture migration generate different swelling behavior/kinetics in dark chocolate during storage. Moisture migration resulted in a rapid swelling once a water activity of 0.8 was reached in the chocolate, probably by interaction and absorption of moisture by the particulate solids. Fat migration also affected the swelling behavior in chocolate, possibly by inducing phase transitions in the continuous cocoa butter phase. Migrating fat also proved to induce a more pronounced swelling than the same amount of absorbed moisture which further consolidated that the observed swelling caused by fat or moisture migration is a result of significant different mechanisms.     

Acrylamide in almond products

Acrylamide was determined in 86 different almond products, such as roasted almonds, almond-containing bakery products, raw almonds, and marzipan. The highest acrylamide concentrations were found in dark roasted almonds, while only moderate acrylamide contents were determined in bakery products. Roasting experiments under different process conditions showed that acrylamide increases with time and that temperature has a much stronger effect on acrylamide formation than time. During roasting reducing sugars are consumed faster and to a larger extent than free asparagine, suggesting that the content of reducing sugars may be a critical factor for acrylamide formation in roasted almonds. Acrylamide was found to decrease in roasted almonds during storage at room temperature.     

MEASUREMENT OF YIELD STRESS IN DARK CHOCOLATE USING CONTROLLED STRESS VANE METHOD

The controlled stress vane method was used to measure the yield stress in dark chocolate. Three vanes with different L/D ratios and five different stress rates were used in three different chocolate formulations. The vane displacement data did not indicate a definite yield phenomenon. When the vane displacement data were transformed into a ratio of vane velocity to elapsed time, the square root of vane velocity (SV) or the cube root of displacement, a definite yield phenomenon was observed. The SV was preferred on the basis of physical considerations and the linear regression of its derived yield stress on vane dimensions, stress rate and chocolate particle size. The value of the yield stress was the least when determined for a vane height to diameter ratio of 2 and at a stress rate of 3 Pa/min using the SV transformation.     

Light-Oxidized Flavor Development and Vitamin A Degradation in Chocolate Milk

Samples of several chocolate milk formulations were exposed to light to determine if the components masked and/or prevented light-oxidized flavors or prevented photodegradation of vitamin A. Chocolate flavor added either before or after light exposure masked light-oxidized flavor (p<0.05). Neither carrageenan nor chocolate color prevented development of light-oxidized flavor. Vitamin A degradation was reduced by the addition of carrageenan alone or in combination with chocolate dairy powder (chocolate flavor and color), chocolate color or chocolate flavor (p<0.05).     

Dark chocolate acceptability: influence of cocoa origin and processing conditions

BACKGROUND: Chocolate properties can vary depending on cocoa origin, composition and manufacturing procedure, which affect consumer acceptability. The aim of this work was to study the effect of two cocoa origins (Ghana and Ecuador) and two processing conditions (roasting time and conching time) on dark chocolate acceptability. RESULTS: Overall acceptability and acceptability for different attributes (colour, flavour, odour and texture) were evaluated by 95 consumers. Differences in acceptability among dark chocolates were mainly related to differences in flavour acceptability. The use of a long roasting time lowered chocolate acceptability in Ghanaian samples while it had no effect on acceptability of Ecuadorian chocolates. This response was observed for most consumers (two subgroups with different frequency consumption of dark chocolate). However, for a third group of consumers identified as distinguishers, the most acceptable dark chocolate samples were those produced with specific combinations of roasting time and conching time for each of the cocoa geographical origin considered. CONCLUSION: To produce dark chocolates from a single origin it is important to know the target market preferences and to select the appropriate roasting and conching conditions. Copyright © 2011 Society of Chemical Industry     

Effect of food matrix and processing on release of almond protein during simulated digestion

The aims of the present work were to assess digestibility of almond protein in the upper gastrointestinal tract, evaluate the effects of food matrix on protein release and assess the persistence of immunoreactive polypeptides generated during simulated digestion. Prunin, the most abundant protein in almond flour, was sensitive to pepsin, with complete digestion after 20 min in the gastric phase. Addition of the surfactant phosphatidylcholine did not affect the rate and kinetic of digestion, as observed by SDS-PAGE analysis and HPLC, in the stomach and the small intestine of either natural or blanched almond flour. However, incorporation of almond flour into a food matrix, such as chocolate mousse and Victorian sponge cake, decreased the rate of almond protein degradation by pepsin and immunoreactivity of almond polypeptides detected by dot blots and sandwich ELISA retained better. Most of the almond protein identified by in-gel tryptic digestion and MALDI-TOF analysis corresponded to prunin, with pI values of 5–7.     

Effect of poly-γ-glutamic acids (PGA) on oil uptake and sensory quality in doughnuts

Poly-γ-glutamic acid (PGA) was added to doughnut formulations to reduce oil uptake during deep-fat frying. At a frying time of 4 min, oil uptake in control doughnuts reached about 0.7 g/g of dough, while that of doughnuts with PGA was about 0.2 g/g of dough. The extent of oil reduction increased by 5-fold when the concentration of PGA was increased from 0.25 to 1 g/100 g of dough. In scanning electron micrographs, a PGA doughnut showed a less void and denser matrix with improved integrity. Significantly (p<0.05) higher sensory scores for appearance, taste, and overall acceptability were given to the PGA doughnut (1 g/100 g dough). PGA has great potential to be used as a healthy functional oilreducing agent in deep-fat fried products.     

Technofunctional barrier layers for preventing fat bloom in triple-shot pralines

The storage stability of dark chocolate with nougat fillings is mainly limited by the formation of fat bloom, which arises because of the migration of nut oil from the filling to the outside of the chocolate shell where it leads to the formation of visible cocoa butter crystals. The triple-shot technique, which allows the simultaneous deposition of three viscous fluids, was applied for the laboratory-scale manufacture of pralines with a technofunctional barrier layer to prevent blooming. Base component of the barrier layer was palm kernel oil, pure or in combination with milk fat; micro-milled sugar or skim milk powder served as disperse phase. As compared to control experiments, the formation of fat bloom was significantly reduced for selected barrier layers because of the reduced transfer of nut oil to the outside of the praline shells. These results indicate that triple-shot depositing is a promising technique for the manufacture of filled chocolate with enhanced physical shelf life.