OBSERVATIONS OF CHOCOLATE DURING CONCHING BY SCANNING ELECTRON MICROSCOPY AND VISCOMETRY

Dark semi-sweet chocolate samples, obtained at various times during conching, were cooled and prepared for examination by scanning electron microscopy (SEM) in an attempt to observe structural changes during conching. In addition, ingredient mixtures containing known amounts of cocoa solids, microcrystalline cellulose, starch, sucrose and lecithin were studied to correctly identify the components of chocolate. Pulverized sucrose particles were easily characterized by their smooth surfaces and heterogeneous shapes. Defatted chocolate liquor was rougher in appearance and smaller in size than sucrose. Cellular detail of the cocoa bean was evident in liquor even after the disruptive effect of refining. Lecithin, when added to liquor-sugar and cocoa butter-sugar mixtures, had a remarkable and rapid effect in reducing three-dimensional structure. When processed chocolates from four different conches were examined by SEM, little or no differences were observed in the size or shape of the sugar or liquor particles as conching proceeded. Surface smoothening, however, was noted and attributed to the homogenization or spreading of cocoa butter during conching. When lecithin was added to chocolate during conching the surfaces were reduced and appeared to flatten. The effect of lecithin in reducing surface tension was also supported by viscometry. Viscometric measurements taken at this time showed that the increase in fluidity was accompanied by a sharp and rapid decrease in plastic viscosity.     

In-situ lecithination of dairy powders in spray-drying for confectionery applications

Powders are essential ingredients of chocolate. In particular for milk chocolate milk and whey powders are important, together with sucrose, lactose and cocoa solids. During processing to maintain a good flow of the molten chocolate mass, particles with hydrophilic surfaces, such as dairy powders and sugars, are coated with a surface-active compound. Only lecithin and polyglycerol polyricinoleate (PGPR) (at a limited level) are allowed in chocolate, and as these are expensive as little as possible is added, whilst maintaining rheological properties. Conventionally, lecithin is added during conching, and through the intense kneading of the chocolate mass it is distributed throughout the mass. Usually about 0.5% is added, although the level depends upon the composition of the chocolate. Here we present a new approach to lecithination of spray-dried milk and lactose powders, which we call in-situ lecithination. It has been found that the surface of a spray-dried powder is dominated by any surface-active species, and in a competitive situation, the most rapidly adsorbing species dominates. This behaviour is utilised when lecithin is added to the spray-dryer feed, and through the competitive adsorption of surface-active agents during the drying process, it dominates the powder surface composition as measured by X-ray photoelectron spectroscopy (XPS). This is also seen in differences in sedimentation rate when the powders are mixed with cocoa butter to assess the rheological properties of the powder dispersions. The effect was large for lactose powders, but smaller for skim milk powder and whey powder.     

可可粉末香精的感官分析及其在食品中的应用

研究了可可粉末香精作为可可粉的代替物在食品中的应用,通过感官分析从整体喜好度、香气、巧克力风味、苦味、口感五个方面对样品进行评价,并通过SPSS软件对所得数据进行方差分析.实验得出可可粉末香精能替代可可粉,同时在感官分析中没有明显差异.试验得出可可粉末香精在不同食品中可可粉的代替量,在水中溶解0.02％可可粉末香精可替代0.25％可可粉：在奶粉和牛奶中0.04％的可可粉末香精可替代0.25％的可可粉;在冰淇淋中0.05％的可可粉末香精可替代0.5％的可可粉;在饼干夹心中0.15％的可可粉末香精可代替2.5％的可可粉末.通过实验可以看出可可粉末香精在不影响产品感官品质的同时能大大降低可可粉的用量,降低产品的成本.     

彩色花生巧克力豆加工工艺技术及设备

本文介绍了制作花生巧克力所需设备以及设备的基本工作原理、构造和使用方法;探讨了彩色巧克力豆制作过程的工艺条件和配方。采用巧克力花生豆成套设备,以花生为芯料,可可粉、可可脂、糖粉、卵磷脂、色素和抛光剂按一定的比例,可制作出来色泽光亮、营养丰富、风味独特的花生巧克力豆。     

Chocolate at a Sliding Interface

The tribological properties of a chocolate‐lubricated tribo‐system have been measured with a pin‐on‐disk tribometer employing poly(tetrafluoroethylene) (PTFE)/zirconia (ZrO₂) as the tribo‐pair. For this study, a series of test chocolate samples was prepared by systematic variation of conching type, particle‐size distribution, milk fat/cocoa butter ratio, and lecithin content. Tribological measurements were found to be sensitive to lecithin content for all particle sizes investigated, while only being sensitive to particle size at high lecithin content. Rheological measurements were found to be sensitive to lecithin content in the case of small particle size, and sensitive to particle size in the case of low lecithin content.     

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     

Rejection Thresholds in Chocolate Milk: Evidence for Segmentation

Bitterness is generally considered a negative attribute in food, yet many individuals enjoy some bitterness in products like coffee or chocolate. In chocolate, bitterness arises from naturally occurring alkaloids and phenolics found in cacao. Fermentation and roasting help develop typical chocolate flavor and reduce the intense bitterness of raw cacao by modifying these bitter compounds. As it becomes increasingly common to fortify chocolate with `raw' cacao to increase the amount of healthful phytonutrients, it is important to identify the point at which the concentration of bitter compounds becomes objectionable, even to those who enjoy some bitterness. Classical threshold methods focus on the presence or absence of a sensation rather than acceptability or hedonics. A new alternative, the rejection threshold, was recently described in the literature. Here, we sought to quantify and compare differences in Rejection Thresholds (RjT) and Detection Thresholds (DT) in chocolate milk spiked with a food safe bitterant (sucrose octaacetate). In experiment 1, a series of paired preference tests was used to estimate the RjT for bitterness in chocolate milk. In a new group of participants (experiment 2), we determined the RjT and DT using the forced choice ascending method of limits. In both studies, participants were segmented on the basis of self-declared preference for milk or dark solid chocolate. Based on sigmoid fits of the indifference-preference function, the RjT was ~2.3 times higher for those preferring dark chocolate than the RjT for those preferring milk chocolate in both experiments. In contrast, the DT for both groups was functionally identical, suggesting that differential effects of bitterness on liking of chocolate products are not based on the ability to detect bitterness in these products.     

Sensory profile,acceptability, and their relationship for diabetic/reduced calorie chocolates

The purpose of this study was to determine the sensory properties and acceptability of lab developed prototypes of conventional, diabetic (with no sugar), and diabetic/reduced calorie milk chocolates (no sugar and 25% calorie reduction) with high-intensity sweeteners, sucralose and stevioside, and partial fat replacement with whey protein concentrate (WPC). PLS was performed in order to relate sensory properties and consumer acceptability and to determine drivers of liking and disliking. There was no difference between conventional, diabetic and diabetic/reduced calorie milk chocolates for brightness, cocoa aroma, cocoa butter aroma, and cocoa flavor (p > 0.05). Acceptability was higher for sucrose substitution by sucralose than by stevioside and partial fat replacement reduced acceptability of flavor even more (p ? 0.05). Crucial attributes which determine consumer acceptability in samples are sweet aroma, melting rate, and sweetness, whereas bitterness, bitter aftertaste, adherence, and sandiness were drivers of disliking.     

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.     

巧克力香精新典范——可可脂浓缩物

<正> 钟情于巧克力的消费者们所关注的是巧克力的风味和产品所富含的奶油口感。在市场倡导天然健康食品的今天,为达到上述两个质量重点而又能减少产品的脂肪含量,原料供应商便开发出一种称为可可脂浓缩物的配料产品、在提供浓郁芳香口味的同时,能降低生产成本及加工方面所受的限制,也减少了产品的脂肪含量,为巧克力产品生产商及消费者带来了佳音。 风味质感来源 浓郁的巧克力香味基本上取决于可可豆中香味物质正确的平衡比例,这是因为某些香味特征只来自可可固体物,部分则来自可可豆的脂肪中,而来自可可固体物的香味又比来自可可脂肪的最     

Explaining tolerance for bitterness in chocolate ice cream using solid chocolate preferences

Chocolate ice cream is commonly formulated with higher sugar levels than nonchocolate flavors to compensate for the inherent bitterness of cocoa. Bitterness, however, is an integral part of the complex flavor of chocolate. In light of the global obesity epidemic, many consumers and health professionals are concerned about the levels of added sugars in foods. Once a strategy for balancing undesirable bitterness and health concerns regarding added sugars has been developed, the task becomes determining whether that product will be acceptable to the consumer. Thus, the purpose of this research was to manipulate the bitterness of chocolate ice cream to examine how this influences consumer preferences. The main goal of this study was to estimate group rejection thresholds for bitterness in chocolate ice cream, and to see if solid chocolate preferences (dark vs. milk) generalized to ice cream. A food-safe bitter ingredient, sucrose octaacetate, was added to chocolate ice cream to alter bitterness without disturbing other the sensory qualities of the ice cream samples, including texture. Untrained chocolate ice cream consumers participated in a large-scale sensory test by indicating their preferences for blinded pairs of unspiked and spiked samples, where the spiked sample had increasing levels of the added bitterant. As anticipated, the group containing individuals who prefer milk chocolate had a much lower tolerance for bitterness in their chocolate ice cream compared with the group of individuals who prefer dark chocolate; indeed, the dark chocolate group tolerated almost twice as much added bitterant in the ice cream before indicating a significant preference for the unspiked (control) ice cream. This work demonstrates the successful application of the rejection threshold method to a complex dairy food. Estimating rejection thresholds could prove to be an effective tool for determining acceptable formulations or quality limits when considering attributes that become objectionable at high intensities.     

巧克力风味牛奶的研制与开发

通过选用巧克力香精替代巧克力,以鲜牛奶为主要原料,选用L9(33)正交表,通过正交实验筛选最佳配方。结果表明,鲜牛奶85.0%,复合稳定剂0.16%,巧克力香精0.07%,食用色素0.106%,AK糖0.02%,可可粉0.4%,白砂糖2.0%(均为质量分数,下同)。产品经分析检测符合国家质量卫生标准,口感细腻,巧克力风味浓郁,奶香突出,色泽诱人,是一种很有发展前途的风味牛奶。     

EFFECTS OF ALKALIZED COCOA POWDER AND SOY LECITHIN ON PHYSICAL CHARACTERISTICS OF CHOCOLATE BEVERAGE POWDERS

Chocolate beverage powders (CBPs) were produced from alkalized cocoa powder (ACP) at 10–30% and soy lecithin (SL) at 0–4%. Response surface methodology (RSM) was used to determine the optimum level of ACP and SL on sedimentation, wettability, bulk density, despersibility, moisture content and flavor acceptability. SL was effective on wettability, and it also showed an optimum level for sedimentation and bulk density, while ACP was found to be significant for all physical properties. For sensory evaluation, flavor was acceptable at 20% ACP level soy taste was detected by panelists in CBPs with high SL and low ACP contents. It was found that as the ACP content was increased the soy taste of CBPs decreased. For overall physical characteristics, the optimum levels of 20% of ACP and 2–4% of SL were selected.     

The production of clusters in milk chocolate

Cluster production during conching of milk chocolate leads to defects in chocolate quality. Various conditions of conching, using two types of milk chocolate were examined. Temperature and relative humidity were the parameters that were controlled. The contents of moisture, fat, sucrose and lactose and also cluster development in milk chocolate during conching were evaluated. Representative samples in the conching tests were subjected to particle size analysis (using laser diffraction and sieve methods), X-ray diffraction analysis, polarizing microscopy and sensory evaluation.     

Optimisation of processing conditions and rheological properties using stephan mixer as conche in small‐scale chocolate processing

This study investigated the suitability of Stephan mixer for use as conche during small‐scale chocolate production in an attempt to reduce cost and processing time. Molten chocolate was processed using the Stephan mixer under different temperature and time combinations and Buhler Elk'Olino conche (as reference), and the flow properties (Casson plastic viscosity, Casson yield stress and thixotropy) were studied using a shear‐rate‐controlled rheometer. Optimum settings of 65 °C for 10 min at 443  g dry conching followed by 50 °C for 15 min at 443  g wet conching in the Stephan mixer resulted in similar flow properties as the reference sample. Increasing the blade rotary speed for both dry and wet conching resulted in a decrease in flow properties. The Stephan mixer proved to be suitable for conching small‐scale (approximately 1 kg) chocolate productions and could be explored as a fast and cost‐effective method for small‐scale chocolate conching processes.     

Impact of amorphous and crystalline lactose on milk chocolate properties

Chocolate mass of low viscosity is preferred for most applications. Milk powder influences processing behaviour, flow properties and taste of milk chocolate. The project aimed to investigate influences of skim milk powders containing amorphous or crystalline lactose on flow properties after producing samples by roller milling and conching or alternatively by ball milling. For the first case, it was found that mass consistency before roller milling is strongly influenced by lactose type; producers must specify it and adapt initial mass fat content. Little impact on final products was found after processing milk powders at equilibrium moisture. If predried powders are used for reducing conching time, crystalline lactose leads to chocolate with slightly lower viscosity. At ball mill processing, crystalline lactose resulted in significantly lower viscosity, for example 15% at 40 s^?1; thus, for this process, it can be recommended to use special milk powders high in crystalline lactose content.     

可可脂的结晶特性对巧克力质量的影响

<正> 巧克力的物理性质很大程度上取决于制造过程中所用的可可脂质量,特别是可可脂融化、结晶和固化的方法。以下将对可可脂在巧克力制造过程中的物理与化学特性,以及各种可可脂如何充分地改变巧克力的风味、易碎程度及口感进行讨论。 可可脂的结晶性 晶形的形成 由于可可脂具有复杂的结晶性,可通过多种不同的变性而结晶成多晶型脂肪,正是这些     

Inhibitory Effect of Chocolate Components Toward Lard Detection in Chocolate Using Real Time PCR

An identification method of lard in chocolates using real-time polymerase chain reaction was developed to address Halal authentication. However, polymerase chain reaction detection of lard in chocolate has been in vain. In order to investigate the inhibitory effect exerted by each of the chocolate components, four basic chocolate components, sugar, milk powder, cocoa butter, and cocoa powder, were adulterated with lard and examined using porcine-specific real-time polymerase chain reaction assay. The results discovered cocoa powder, as the only component that prevents DNA extraction of lard in chocolate. No substantial polymerase chain reaction inhibition was detected, and thus confirms the cocoa powder’s inhibition on DNA extraction of lard from lard-adulterated chocolate. This finding will expedite new research to develop a method to dissociate the lard from the lard-cocoa powder complex, which will have high potential to be applied as a pre-treatment of the chocolate prior to the DNA extraction and polymerase chain reaction.     

巧克力专用乳粉

研究了不同乳粉的颗粒大小和结构、游离脂肪含量对巧克力浆料粘度的关系。滚筒乳粉与喷雾乳粉之对比，滚筒干燥的全乳粉具有下列优点；游离脂肪含量高，可减少可脂的用量，赋与巧克力以更好的风味；可降低巧克力浆料的粘度。乳粉中羟甲基糠醛含量可增进巧克力风味、口感，提高喷雾乳粉中游离脂肪含量改进的工艺。