CLA-Rich Chocolate Bar and Chocolate Paste Production and Characterization

Conjugated linoleic acid (CLA) is an 18‐carbon fatty acid with multiple health benefits, including anti‐obesity and anti‐carcinogenic properties. CLA‐rich soy oil (CLARSO) can be produced through a heterogeneous catalysis process, and this oil was previously used to produce CLA‐rich margarines and shortenings. The objectives of this study were to produce CLA‐rich chocolate bars and pastes by replacing a portion of the fat with CLARSO and compare the rheological, textural, and thermal properties of these pastes/bars to controls made with either soy oil or traditional fats. CLARSO was used to prepare bars/pastes. Rheology, firmness, and thermal behavior of the pastes and fracturability, hardness, and thermal behavior of the bars were determined. The CLARSO chocolate pastes/bars contained no additional saturated fat relative to soy oil controls but the pastes had more solid‐like rheology and were firmer and the bars had a higher fracture force relative to soy oil controls. Relative to non‐soy controls, CLARSO pastes had similar rheology and CLARSO bars had similar fracturability, despite containing less saturated fat. The fat crystals of all samples were in the same polymorphic form. Therefore, it was successfully demonstrated that CLARSO has the ability to produce chocolate pastes/bars with similar physical properties as traditional products containing more saturated fat.     

Influence of Individual Phospholipids on the Physical Properties of Oil-Based Suspensions

The impact of soybean lecithin and three individual phospholipids at different concentration (C_PL) on rheology and sedimentation behavior of sugar/soybean oil suspensions (? = 0.31) was studied and compared with attraction and retraction forces between sugar surfaces in soybean oil as measured by atomic force microscopy (AFM). In general, a surfactant‐induced reduction of yield stress, apparent viscosity and sediment volume of the suspensions coincides with a decrease of adhesive interactions between sugar particles in soybean oil. Although the general influence of individual phospholipids and soybean lecithin is comparable, it is concluded from investigations at low C_PL that individual phospholipids exhibit a less pronounced impact on the analyzed parameters. Furthermore, at low C_PL, binary mixtures of the phospholipids are more efficient than individual phospholipids as regards the reduction of yield stress and sediment volume. While the same tendency was detectable for AFM results, these differences were not statistically verified. Slight differences were also evident when comparing individual phospholipids and their influence on rheology and sedimentation which are, however, not in line with the results of AFM. A general understanding of these interrelations between surfactant composition and possible synergistic or antagonistic effects in mixtures of individual phospholipids contributes to optimizing lecithin composition with respect to functionality.     

Crystallization Behavior and Kinetics of Chocolate-Lauric Fat Blends and Model Systems

Binary mixtures of cocoa butter and lauric fats have widespread use in chocolates and confections, yet incompatibilities between these fats can present formulation and processing constraints. This study examined the phase behavior and crystallization kinetics of cocoa butter-lauric fat model systems and chocolate-lauric fat blends. Solid fat content (SFC) profiles and isosolid diagrams confirmed eutectic and diluent interactions, indicating a softening of cocoa butter by lauric fat addition. Crystallization kinetics of model systems adhered to an exponential growth model. High lauric fat levels delayed crystal growth and reduced equilibrium SFC of cocoa butter. Coconut and palm kernel oils altered the solidification mechanisms of cocoa butter to a greater extent than fractionated palm kernel oil. Chocolate systems displayed multi-step crystal growth that contrasted with the exponential growth observed in the model systems. At high lauric fat levels (30%), crystallization onset was significantly lengthened. Blends with high lauric fat contents showed low \(G_{{\text {max}} }^{\prime }\) and did not achieve final equilibrium after 60 min of cooling, indicating incomplete crystallization.     

Laser induced periodic structure on lecithin-doped polyimide film surface and its ability to align liquid crystal molecules

Doping effect of lecithin in polyimide (PI) films on the preparation of laser induced periodic structure (LIPS) was investigated using single-beam polarized pulse UV laser. We found that the regularity of LIPS on lecithin-doped PI film irradiated at 266 nm was better than that at 355 nm and the threshold energy for the preparation of LIPS decreased. The amplitude of LIPS increased with the increase of lecithin content. In addition, lecithin molecules tended to migrate to the film surface after laser irradiation according to FT-IR spectroscopic results. We found that nematic liquid crystal molecules were azimuthally aligned on the irradiated doped PI surface when lecithin content was below 20 wt%, and were vertically aligned when the lecithin content was 30 wt%.     

Influence of shearing and time on the rheological properties of milk chocolate during tempering

The quality of chocolate is highly dependent on proper tempering. During tempering, crystals are formed as the chocolate is subjected to shear. The aim of this work was to evaluate the applicability of traditional rheological techniques to gain a better understanding of the relationship between rheological properties and the degree of shearing and time of tempering. Treatments of two shearing rates (15 and 30 s⁻¹) covering four tempering times (0, 400, 600, and 800 s) were investigated. As samples were cooled from a melt temperature of 50°C, the apparent viscosity followed the Arrhenius equation. An induction time, which was affected by shear rate, was observed during tempering, followed by an increase in apparent viscosity, caused by formation of crystalline structures. Various characteristics of the rewarming curve were attributed to polymorphism. Steady-shear constitutive models assessed after rewarming showed that the yield stress was dependent on shear and tempering time. Collectively, findings showed that traditional rheological methods may be used as tools to investigate crystallization and flow properties of molten chocolate indirectly during tempering.     

大豆磷脂的提取与分析

以新鲜的油脚为原料，经丙酮脱油，正已烷萃取，并以维生素Ｃ为抗氧化剂，制得粉状大豆磷脂。产品的各项指标不仅符合食品添加剂的标准，而且其色泽也有所改善．     

THE EFFECT OF DRYING AND STORAGE OF SOYBEAN ON THE QUALITY OF BEAN,OIL, AND LECITHIN PRODUCTION

ABSTRACT

A comparative study of soybean drying was carried out between one-stage and two-stage (high–low temperature) drying with shade drying as control. In one-stage drying, the beans were dried at 80, 100, 120, and 140°C, respectively while in two-stage drying, beans were dried at 100, 120, and 140°C in the first stage followed by 80°C in the second stage. The evaluation values after drying showed that high drying temperature caused high skin cracks of the beans. Qualities of extracted crude oil characterized by free fatty acids (FFA), peroxide value (PV), phospholipids (PL) and nonhydratable phospholipids (NHP) were not significantly effected at p<0.05 by different drying methods but NHP had the increasing trend with the drying temperature and two-stage dried beans tended to have NHP higher than one-stage dried beans. The quality of protein in meal determined in terms of protein dispersibility index (PDI) was less than 15% when drying temperature in one-stage drying was higher than 80°C and when the temperature at the first stage of two-stage drying was higher than 100°C. Drying temperature also had the effect on the quality of lecithin when considered in term of the acetone insoluble value (AI). Free fatty acids of extracted crude oil increased when dried beans were stored for two months at 35°C while PL decreased especially in the first month of storage. However, the AI value of lecithin did not change with time.     

An aqueous suspension system for phospholipase D-mediated synthesis of PS without toxic organic solvent

Enzymatic synthesis of PS by phospholipase D (PLD)-mediated transphosphatidylation in an aqueous media was investigated. The purpose of this study was to establish a novel synthetic method where no toxic organic solvents were used. An attempt to react soybean lecithin (simply dispersed in an aqueous buffer) with an aqueous solution of l-serine and PLD was unsuccessful, giving only 20% of PS. By contrast, a suspension of lecithin adsorbed on fine powders such as silica was effectively converted into PS in an aqueous solution of l-serine and PLD. After screening various powders for use as the lecithin adsorbent, calcium sulfate was found to be the best with respect to lecithin conversion. In addition, calcium sulfate did not require prior adsorption of lecithin (i.e., the reaction proceeded effectively simply by adding the powder to an aqueous mixture of lecithin, l-serine, and PLD). With this “aqueous suspension system” of calcium sulfate, up to 180 mg/mL lecithin was completely converted, resulting in more than 80% PS in 24 h. The synthesized PS could easily be recovered from the powder by extracting with a mixture of n-hexane, ethanol, and diluted HCl.     

水杨酸壳聚糖/卵磷脂纳米粒的制备

采用溶剂注入法制备水杨酸壳聚糖/卵磷脂纳米粒。考察了粒子结构、形貌特征及表面电位等性能,并探讨了制备工艺对药物包封率的影响。确定最佳制备工艺为:卵磷脂质量浓度20 g/L、卵磷脂与壳聚糖及水杨酸与载体的质量比分别为3∶1和1∶6、水相pH=4。所制备的水杨酸壳聚糖/卵磷脂固体纳米粒子为球形粒子、表面电位+18.7 mV、包封率及载药量可分别达到55%和8.07%。     

Impact of Limonene on the Physical Properties of Reduced Fat Chocolate

The addition of limonene, a low molecular weight hydrophobic compound, to chocolate was reported to decrease the hardness and the viscosity of chocolate, facilitating the production and improving the eating quality of reduced fat chocolate. The objective of this study is to understand the functionality of limonene in decreasing the viscosity and the hardness of chocolate, a fat (cocoa butter)-based particulate suspension. This study shows that chocolate hardness was decreased because limonene mixes with cocoa butter, affects its crystallization pattern and decreases its solid fat content. After checking that limonene does not significantly affect the continuous phase volume fraction, we show that limonene decreases chocolate viscosity by decreasing the viscosity of the continuous phase, cocoa butter. The addition of low quantities of limonene in cocoa butter leads to a great decrease in the liquid fat viscosity. The dependence of the viscosity on the ratio of cocoa butter to limonene analyzed using Kay’s equation seems to indicate that limonene mixes with and within the cocoa butter triglycerides, diluting the fat and leading to a decrease in the overall fat viscosity.     

Olive oil microemulsions as a biomimetic medium for enzymatic studies: Oxidation of oleuropein

Microemulsions consisting of olive oil as the non-polar solvent, lecithin as surfactant, 1-propanol as cosurfactant, and water were prepared. The choice of the compositions of the microemulsions used was based on the pseudo-ternary phase diagrams of the system determined at 30°C, for different weight ratios of lecithin/olive oil. Lecithin solubilization and water incorporation in these microemulsion systems was limited. Tyrosinase, an oxidizing enzyme present in olives, was successfully incorporated in the water core of these microemulsions. Enzymatic oxidation of oleuropein, the most abundant olive phenolic compound, in the restricted aqueous environment of olive oil microemulsions was studied. Formation of oleuropein oxidation products was followed spectrophotometrically at 30°C for several minutes. An absorption maximum was observed at 415 nm. When the enzymatic reaction was considered at different tyrosinase and oleuropein concentrations, a rapid inactivation of the enzyme was observed. Addition of l-proline as a coupling reactor did not succeed in preventing enzyme inactivation in the microemulsions, probably owing to substrate localization and product accumulation around the entrapped enzyme molecules in the micellar interface.     

Applications of milk-fat fractions in confectionery products

Incompatibilities between fats limit the use of modified milk fat in confectionery applications. To further enhance the use of milk-fat fractions in chocolates and compound coatings, a better understanding of mixed crystallization effects between lipids is required. Recent work documents that highmelting fractions incorporated into chocolates drastically reduce bloom formation and cause less softening than anhydrous milk fat. Isosolids diagrams for mixtures of cocoa butter and milk-fat fractions show that softening occurs due to both dilution effects and a slight eutectic formation. Incorporation of milk-fat fractions into palm kernel oil-based coatings shows some differences with results in chocolates. Milk fat and its fractions cause significant bloom formation in these coatings, as compared to the control, and cause significant softening. However, both milk fat and milk-fat fractions are fully compatible with palm kernel oil, based on isosolids diagrams. Softening occurs only because of dilution effects, rather than eutectic formation. Further work is necessary to understand the effects of milk-fat fractions on bloom formation in compound coatings. Presented at the 1995 AOCS Annual Meeting & Expo, San Antonio, Texas, May 1995.     

天然高纯度卵磷脂的超临界CO2萃取

用超临界ＣＯ２萃取技术从大豆粗磷脂中萃取天然高纯度卵磷脂,用正交实验的方法得到了优化工艺条件,即萃取压力３０ＭＰａ,萃取温度５０℃,萃取时间为６ｈ。产品纯度为９８％。残油产量４３％,该法比溶剂法优越,产品质量高,为开发和综合利用大豆资源开发避了新的途径。