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.     

Utilisation of red palm olein in formulating functional chocolate spread

Novel functional chocolate spreads were formulated by replacing butter fat in conventional chocolate spread by red palm olein at 20%, 40%, 60%, 80% and 100% levels. Sensory evaluation revealed that chocolate spread made from 20% red palm olein (RPOL) and 80% butter fat was accepted as the conventional chocolate spread (100% butter fat). Hence, the former two chocolate spreads were selected for further study. Samples were stored at room temperature and fridge for 6 months and monitored for their physical properties, fat stability, fatty acid composition and natural antioxidants.     

The application of Borneo tallow in dark chocolate shell

Dark chocolate shells, formulated using cocoa butter (CB shell), and fat blends containing 15% Borneo tallow (IP) in cocoa butter (CBIP shell), were filled with truffles formulated using white chocolate (W truffle), milk chocolate (M truffle) and dark chocolate (D truffle). Anhydrous milk fat (AMF) content of the W truffles, M truffle and D truffle were 26·3%, 13·7% and 9·2%, respectively. Degree of tempering was determined using a tempermeter. The chocolates were kept at ambient temperature (25·5±0·5°C) for 3 months. Physical changes of chocolate shells and centres were monitored using DSC and a texture analyser. Results showed that the CBIP shell had to be tempered at 32·5%, ie 1°C higher than the normal CB shell. Physical measurements indicated the occurrence of fat migration. The presence of IP reduced the effect and increased the bloom resistance of the chocolate. © 1998 SCI.     

Lipid migration in two-phase chocolate systems investigated by NMR and DSC

The migration of lipids in two-phase chocolate systems (i.e. lauric acid+chocolate and peanut butter+chocolate) was analyzed by magnetic resonance and differential scanning calorimetry. Kinetics of fat migration was evaluated and the diffusion coefficient of lauric acid in chocolate was found to be dependent on migration time. This may be due to the capillary nature of fat migration in chocolate. Fat bloom characteristics were determined and related to the thermal history of samples and the presence of fat in the chocolate layer. Both lauric acid and peanut butter increased the liquid-to-solid ratio of chocolate and helped prevent fat bloom.     

Heat tolerance of Salmonella enterica serovars Agona, Enteritidis, and Typhimurium in peanut butter

Recent large foodborne outbreaks caused by Salmonella enterica serovars have been associated with consumption of foods with high fat content and reduced water activity, even though their ingredients usually undergo pasteurization. The present study was focused on the heat tolerance of Salmonella enterica serovars Agona, Enteritidis, and Typhimurium in peanut butter. The Salmonella serovars in the peanut butter were resistant to heat, and even at a temperature as high as 90 degrees C only 3.2-log reduction in CFU was observed. The obtained thermal inactivation curves were upwardly concave, indicating rapid death at the beginning (10 min) followed by lower death rates and an asymptotic tail. The curves fitted the nonlinear Weibull model with beta parameters < 1, indicating that the remaining cells have a lower probability of dying. beta at 70 degrees C (0.40 +/- 0.04) was significantly lower than beta at 80 degrees C (0.73 +/- 0.19) and 90 degrees C (0.69 +/- 0.17). Very little decrease in the viable population (less than 2-log decrease) was noted in cultures that were exposed to a second thermal treatment. Peanut butter is a highly concentrated colloidal suspension of lipid and water in a peanut meal phase. We hypothesized that differences in the local environments of the bacteria, with respect to fat content or water activity, explained the observed distribution and high portion of surviving cells (0.1%, independent of the initial cell number). These results demonstrate that thermal treatments are inadequate to consistently destroy Salmonella in highly contaminated peanut butter and that the pasteurization process cannot be improved significantly by longer treatment or higher temperatures.     

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.     

Effect of temperature of CO2 injection on the pH and freezing point of milks and creams

The objectives of this study were to measure the impact of CO2 injection temperature (0 degree C and 40 degrees C) on the pH and freezing point (FP) of (a) milks with different fat contents (i.e., 0, 15, 30%) and (b) creams with 15% fat but different fat characteristics. Skim milk and unhomogenized creams containing 15 and 30% fat were prepared from the same batch of whole milk and were carbonated at 0 and 40 degrees C in a continuous flow CO2 injection unit (230 ml/min). At 0 degree C, milk fat was mostly solid; at 40 degrees C, milk fat was liquid. At the same total CO2 concentration with CO2 injection at 0 degree C, milk with a higher fat content had a lower pH and FP, while with CO2 injection at 40 degrees C, milks with 0%, 15%, and 30% fat had the same pH. This indicated that less CO2 was dissolved in the fat portion of the milk when the CO2 was injected at 0 degree C than when it was injected at 40 degrees C. Three creams, 15% unhomogenized cream, 15% butter oil emulsion in skim milk, and 15% vegetable oil emulsion in skim milk were also carbonated and analyzed as described above. Vegetable oil was liquid at both 0 and 40 degrees C. At a CO2 injection temperature of 0 degree C, the 15% vegetable oil emulsion had a slightly higher pH than the 15% butter oil emulsion and the 15% unhomogenized cream, indicating that the liquid vegetable oil dissolved more CO2 than the mostly solid milk fat and butter oil. No difference in the pH or FP of the 15% unhomogenized cream and 15% butter oil emulsion was observed when CO2 was injected at 0 degree C, suggesting that homogenization or physical dispersion of milk fat globules did not influence the amount of CO2 dissolved in milk fat at a CO2 injection temperature of 0 degree C. At a CO2 injection temperature of 40 degrees C and at the same total CO2 concentration, the 15% unhomogenized cream, 15% vegetable oil emulsion, and 15% butter oil emulsion had similar pH. At the same total concentration of CO2 in cream, injection of CO2 at low temperature (i.e., < 4 degrees C) may produce a better antimicrobial effect during refrigerated shelf life due to the higher concentration of CO2 in the skim portion of the cream.     

Peanut allergen (Ara h 1) detection in foods containing chocolate

Inadvertent exposure to peanut in foods poses health risks for peanut-allergic individuals that can be reduced by improving detection systems for allergen contaminants in food products and manufacturing processes. Detection of peanut in chocolate has been especially difficult. We report the optimization of conditions for measuring a major peanut allergen, Ara h 1, in chocolate with the use of a two-site monoclonal antibody sandwich enzyme-linked immunosorbent assay. Ara h 1 was extracted from peanut in the presence or absence of chocolate with phosphate buffer, salt, and three dried milks (goat, soy, or nonfat) (0 to 25% wt/vol) for 15 min at 60 degrees C or for 2.5 h at room temperature. The best conditions for Ara h 1 extraction in the presence of chocolate were 5% nonfat dry milk for 2.5 h at room temperature. Spiking experiments of chocolate with peanut confirmed improvement of the extraction: Ara h 1 was detected in extractions of 0.16 to 0.33% peanut in chocolate. Interestingly, the best conditions for Ara h 1 extraction were different for peanut alone than with chocolate, regarding time, temperature, and percentage of nonfat dry milk in the extraction buffer. In chocolate with peanut foods, the total Ara h 1 values were 10-fold higher than when products were extracted with phosphate buffer alone and could be up to 400-fold higher for individual foods. The dramatic improvement of Ara h 1 extraction should allow specific allergen monitoring in chocolate-containing food products and assessment of Ara h 1 exposure.     

Effects of milk fat, cocoa butter, or selected fat replacers on flavor volatiles of chocolate ice cream

Selected volatile compounds of chocolate ice creams containing 0.6, 4.0, 6.0, or 9.0% milk fat or containing 2.5% milk fat, cocoa butter, or one of three fat replacers (Simplesse, Dairy Lo, or Oatrim) were analyzed by gas chromatography and gas chromatography-mass spectrometry using headspace solid-phase microextraction. The headspace concentration of most of the selected volatile compounds increased with decreasing milk fat concentration. Fat replacers generally increased the concentration of volatiles found in the headspace compared with milk fat or cocoa butter. Few differences in flavor volatiles were found between the ice cream containing milk fat and the ice cream containing cocoa butter. Among the selected volatiles, the concentration of 2,5-dimethyl-3(2-methyl propyl) pyrazine was the most highly correlated (negatively) with the concentration of milk fat, and it best discriminated among ice creams containing milk fat, cocoa butter, or one of the fat replacers.     

Survival of Listeria monocytogenes during the manufacture and ripening of Swiss cheese.

Rindless Swiss cheese was made from a mixture of pasteurized whole and skim milk that was inoculated to contain 10(4) to 10(5) cfu of Listeria monocytogenes (strain Ohio, California, or V7)/ml. During clotting of milk, numbers of L. monocytogenes remained nearly unchanged. When the curd was heated gradually to attain the cooking temperature (50 degrees C), numbers of L. monocytogenes increased by approximately 40 to 45% over those in inoculated milk. Cooking curd at 50 degrees C (122 degrees F) for 30 to 40 min resulted in resilient curd having a pH of 6.40 to 6.45 and decreased L. monocytogenes by 48% compared with numbers of the pathogen in inoculated milk. After curd was pressed under whey, numbers of L. monocytogenes increased by approximately 52% over those in inoculated milk and reached their maxima at the end of this stage. A sharp decrease in numbers of L. monocytogenes occurred during brining of cheese blocks (7 degrees C for 30 h). The population of L. monocytogenes continued to decrease during cheese ripening. Average D values for strains California, Ohio, and V7 were 29.2, 24, and 22.5 d, respectively. Listeria was not detected (direct plating, and cold enrichment) after 80, 77, and 66 d of ripening of Swiss cheese made from milk inoculated with strains California, Ohio, and V7, respectively. Thus, Swiss cheese made in this study did not permit extended survival of L. monocytogenes.     

Development of a Chocolate Flavored Peanut Beverage

Nine chocolate-flavored peanut beverages (CFPB) were prepared using peanut protein isolate as source of protein and analyzed for physical-microbiological-sensory qualities. The quality attributes such as color, aroma, viscosity, and flavor of CFPB were similar to that of commercial chocolate milk. The total aerobic populations of the beverage before and after refrigeration for 7 days were less than 10 and 200 colonies/g, respectively, and no coliform bacteria was detected in this product. Sensory evaluation and response surface methodology indicated that optimum formulation of CFPB was obtained by using 3.5% protein (from peanut protein isolate), 3.5% butter, 8% sugar, 0.7% cocoa powder, 0.1% stabilizer, and water. Consumer study of the CFPB revealed that all sensory characteristics were acceptable in the range of like to extremely like.     

Viability of Clostridium perfringens,Escherichia coli,and Listeria monocytogenes surviving mild heat or aqueous ozone treatment on beef followed by heat,alkali, or salt stress

The threat of pathogen survival following ozone treatment of meat necessitates careful evaluation of the microorganisms surviving under such circumstances. The objective of this study was to determine whether sublethal aqueous ozone treatment (3 ppm of O3 for 5 min) of microorganisms on beef surfaces would result in increased or decreased survival with respect to subsequent heat, alkali, or NaCl stress. A mild heat treatment (55 degrees C for 30 min) was used for comparison. Reductions in three-strain cocktails of Clostridium perfringens, Escherichia coli O157:H7, and Listeria monocytogenes on beef following the heat treatment were 0.14, 0.77, and 1.47 log10 CFU/g, respectively, whereas reductions following ozone treatment were 1.28, 0.85, and 1.09 log10 CFU/g, respectively. C. perfringens cells exhibited elevated heat resistance at 60 degrees C (D60 [time at 60 degrees C required to reduce the viable cell population by 1 log10 units or 90%] = 17.76 min) following heat treatment of beef (55 degrees C for 30 min) but exhibited reduced viability at 60 degrees C following ozone treatment (D60 = 7.64 min) compared with the viability of untreated control cells (D60 = 13.84 min). The D60-values for L. monocytogenes and E. coli O157:H7 following heat and ozone exposures were not significantly different (P > 0.05). C. perfringens cells that survived ozone treatment did not exhibit increased resistance to pH (pH 6 to 12) relative to non-ozone-treated cells when grown at 37 degrees C for 24 h. The heat treatment also resulted in decreased numbers of surviving cells above and below neutral pH values for both E. coli O157:H7 and L. monocytogenes relative to those of non-heat-treated cells grown at 37 degrees C for 24 h. There were significant differences (P < 0.05) in C. perfringens reductions with increasing NaCl concentrations. The effects of NaCl were less apparent for E. coli and L. monocytogenes survivors. It is concluded that pathogens surviving ozone treatment of beef are less likely to endanger food safety than are those surviving sublethal heat treatments.     

GRINDING SPRAY-DRIED MILK POWDER NEAR the GLASS TRANSITION TEMPERATURE

The fine grinding of chocolate is typically accomplished on five‐roll mills. Chocolate manufacturers consider milk powder, a component of milk chocolate, difficult to grind. Spray‐dried milk powders comprise a glassy lactose matrix in which fat globules, air vacuoles and protein are entrapped. the glassy‐rubbery transition in commercial milk powders usually lies between 60–70C, depending on the moisture content. A mixture of 60% wt/wt commercial whole milk powder, T_g～ 60C, and 40% wt/wt cocoa butter was ground in a three‐roll refiner at temperatures of 40, 50, 60, 70 and 75C. Below T_g the particles exhibited brittle fracture, while above T_g plastic deformation was evident and particles became highly asymmetric. the amount of fat liberated from the lactose matrix, so‐called free fat, particle density, and mean particle size increased with grinding temperature. However, the Casson yield value and plastic viscosity of finished “white chocolate” coatings, manufactured to a constant free fat content, increased with grinding temperature, suggesting an influence of particle shape on flow behavior.     

Death of Salmonella,Escherichia coli O157:H7, and Listeria monocytogenes in garlic butter as affected by storage temperature

Garlic is known to have antimicrobial activity against several spoilage and pathogenic bacteria. However, the fate of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in garlic butter has not been reported. This study was undertaken to determine the viability of these organisms in garlic butter as affected by the type of raw minced garlic added to the butter, storage temperature, and storage time. Unsalted butter at 40 degrees C was combined with raw minced jumbo, elephant, or small-cloved garlic at a 4:1 butter/garlic ratio (wt/wt), inoculated with mixed-strain suspensions of Salmonella, E. coli O157:H7, or L monocytogenes, and stored at 4.4, 21, or 37 degrees C for up to 48 h. All pathogens retained their viability at 4.4 degrees C, regardless of the presence of garlic. The addition of garlic to butter enhanced the rates of inactivation of all three pathogens at 21 and 37 degrees C. The most rapid decline in pathogen populations was observed at 37 degrees C. The inactivation of L. monocytogenes occurred more slowly than did that of Salmonella or E. coli O157:H7. The inactivation of Salmonella and L. monocytogenes was more rapid in jumbo garlic butter than in elephant or small-cloved garlic butter. It is concluded that Salmonella, E. coli O157:H7, and L. monocytogenes did not grow in unsalted butter, with or without garlic added (20%, wt/wt), when inoculated products were stored at 4.4, 21, and 37 degrees C for up to 48 h.     

Evaluation of increased vitamin D fortification in high-temperature, short-time-processed 2% milk, UHT-processed 2% fat chocolate milk, and low-fat strawberry yogurt

The objective of this study was to determine the effect of increased vitamin D fortification (250 IU/serving) of high-temperature, short-time (HTST)-processed 2% fat milk, UHT-processed 2% fat chocolate milk, and low-fat strawberry yogurt on the sensory characteristics and stability of vitamin D during processing and storage. Three replicates of HTST pasteurized 2% fat milk, UHT pasteurized 2% fat chocolate milk, and low-fat strawberry yogurt were manufactured. Each of the 3 replicates for all products contained a control (no vitamin D fortification), a treatment group with 100 IU vitamin D/serving (current level of vitamin D fortification), and a treatment group with 250 IU vitamin D/serving. A cold-water dispersible vitamin D₃ concentrate was used for all fortifications. The HTST-processed 2% fat milk was stored for 21 d, with vitamin D analysis done before processing and on d 0, 14, and 21. Sensory analysis was conducted on d 14. The UHT-processed 2% fat chocolate milk was stored for 60 d, with vitamin D analysis done before processing and on d 0, 40, and 60. Sensory analysis was conducted on d 40. Low-fat strawberry yogurt was stored for 42 d, with vitamin D analysis done before processing, and on d 0, 28, and 42. Sensory analysis was conducted on d 28. Vitamin D levels in the fortified products were found to be similar to the target levels of fortification (100 and 250 IU vitamin D per serving) for all products, indicating no loss of vitamin D during processing. Vitamin D was also found to be stable over the shelf life of each product. Increasing the fortification of vitamin D from 100 to 250 IU/serving did not result in a change in the sensory characteristics of HTST-processed 2% fat milk, UHT-processed 2% fat chocolate milk, or low-fat strawberry yogurt. These results indicate that it is feasible to increase vitamin D fortification from 100 to 250 IU per serving in these products.     

Physical and processing properties of milk,butter, and cheddar cheese from cows fed supplemental fish meal

Physical, chemical, sensory and processing properties of milk produced by feeding a rumen-undegradable fish meal protein supplement to Holstein cows were investigated. The supplement contained (as fed basis) 25% soft-white wheat, 60% herring meal, and 15% feather meal. The total fat level in the milk decreased to 2.43%. For both pasteurized and ultra-high temperature processed drinking milk, no difference was found between fish meal (FM) milk and control milk in terms of color, flavor and flavor stability; in particular, no oxidized flavor was observed. Cheddar cheese made from FM milk ripened faster after 3 mo of ripening and developed a more desirable texture and stronger Cheddar flavor. The yield efficiencies for FM and control cheese, 94.4 (+/- 2.44 SE) and 96.4 (+/- 2.26 SE), respectively, were not different. Relative to controls, average fat globule size was smaller in FM milk and churning time of FM cream was longer. FM butter had softer texture and better cold spreadability, and butter oils from FM enriched milk had lower dropping points compared to control butter oil (average 32.89 versus 34.06 degrees C). These differences in physical properties of butter fat were greater than expected considering that iodine values were not different. This study demonstrates the feasibility of producing high quality products from milk naturally supplemented with FM, but the results also show that dietary changes affect processing properties.     

Effect of preinoculation growth media and fat levels on thermal inactivation of a serotype 4b strain of Listeria monocytogenes in frankfurter slurries

Preinoculation growth conditions and fat levels were evaluated for effects on the heat resistance of Listeria monocytogenes strain MFS 102 in formulated frankfurter slurries and on frankfurter surfaces. Comparison of linear inactivation rates (D-values) for cells heated in frankfurter slurry showed that growth conditions were significant (P<0.05) factors affecting subsequent thermal resistance. The average D(60 degrees C)-values for the five preinoculation growth media tested from most resistant to least heat resistant were: tryptic soy broth with 0.6% yeast extract (TSBYE) (2.2 min) and 8.5% fat slurry (2.2 min), followed by 23% fat slurry (1.7 min) and 11% fat slurry (1.7 min), and then TSYBE with quaternary ammonium compounds added (TSBYE+Q) (1 min). The fat level in the frankfurter heating media also had a significant (P<0.05) effect on the thermal death rate of L. monocytogenes. Cells heated in 8.5% fat slurry had a significantly higher (P<0.05) D(60 degrees C)-value (2.2 min) than those heated in 11% fat (1.0 min) and 23% fat slurry (0.9 min). Growth media (TSBYE, 8.5% fat slurry, and TSBYE+Q), and fat level (15% and 20%), however, were not significant factors (P>0.05) affecting thermal inactivation rates on frankfurter surfaces. Heat inactivation rates were consistently higher on frankfurter surfaces compared to similar treatments done in frankfurter slurry. On frankfurter surfaces, a 2.3- to 5.1-log(10) reduction was achieved after 15 min depending on frankfurter surface type. The time necessary to achieve a 3-log(10) reduction using post-processing pasteurization of frankfurters in a hot water-bath at 60 degrees C almost doubled for cells grown in TSBYE and heated in 23% fat frankfurter slurry (19.6 min) versus cells grown and heated in 8.5% fat frankfurter slurry (10.8 min).     

Heat shock induces barotolerance in Listeria monocytogenes

The aim of this study was to investigate the effect of heat shock on the resistance of Listeria monocytogenes to high pressure processing (HPP). L. monocytogenes ATCC 19115 was grown to stationary phase at 15 degrees C and inoculated into whole ultrahigh-temperature milk at approximately 10(7) CFU/ml. Milk samples (5 ml) were placed into plastic transfer pipettes, which were heat sealed and then heated in a water bath at 48 degrees C for 10 min. Immediately after heat shock, the milk was cooled in water (20 degrees C) for 25 min and then placed on ice. The samples were high pressure processed at ambient temperature (approximately 23 degrees C) at 400 MPa for various times up to 150 s. Following HPP, the samples were spread plated on tryptic soy agar supplemented with yeast extract. Heat shock significantly increased the D400 MPa-value of L. monocytogenes from 35 s in non-heat-shocked cells to 127 s in heat-shocked cells (P < 0.05). Addition of chloramphenicol before heat shock eliminated the protective effect of heat shock (P < 0.05). Heat shock for 5, 10, 15, or 30 min at 48 degrees C resulted in maximal barotolerance (P < 0.05); increasing the time to 60 min significantly decreased survival compared with that at 5, 10, 15, or 30 min (P < 0.05). These results indicate that prior heat shock significantly increases the barotolerance of L. monocytogenes and that de novo protein synthesis during heat shock is required for this enhanced barotolerance.     

Effect of cheese water activity and carbohydrate content on the barotolerance of Listeria monocytogenes scott A

High-pressure processing is an appropriate technique for improving the microbiological safety of packaged ready-to-eat foods. The effect of high-pressure treatment on Listeria monocytogenes Scott A inoculated into fresh Hispánico-type cheese and ripe Mahón cheese was investigated. A 3.8-log reduction in the counts of L. monocytogenes Scott A in fresh cheese was recorded after 3 min at 400 MPa and 12 degrees C, whereas 18 min under the same conditions was required to obtain a 1-log reduction in ripe cheese. Dry matter values were 48.96% for fresh cheese and 58.79% for ripe cheese, and water activity (aw) values were 0.983 and 0.922, respectively. In dehydrated fresh cheese (58.20% dry matter) in which 5% NaCl was added to achieve a 0.904 aw value, L. monocytogenes Scott A counts were lowered by only 0.4 log after treatment for 10 min at 400 MPa. On the other hand, in a 60:40 mixture of ripe cheese:distilled water with a 0.976 aw value, the reduction under the same conditions was 3.9 log. Within the aw range of 0.945 to 0.965, L. monocytogenes Scott A barotolerance was significantly higher in fresh cheese than in ripe cheese for equivalent aw values. Carbohydrate content was higher in fresh cheese than in ripe cheese. The addition of lactose at a concentration of 5 mg/g to an 85:15 mixture of ripe cheese:distilled water did not influence L. monocytogenes Scott A barotolerance during treatment for 10 min at 400 MPa. Galactose at a concentration of 5 mg/g had a protective effect during high-pressure treatment, and glucose at a concentration of 5 mg/g favored L. monocytogenes Scott A survival during refrigerated storage of pressurized samples at 8 degrees C for 5 days.