巧克力脂肪起霜的探讨

巧克力的起霜给品质带来了缺陷，使产品的商品价值低下。巧克力的起霜有砂糖起霜与脂肪起霜的区分，多种因素可能引起巧克力脂肪起霜，本文试对巧克力脂肪的成因作些探讨。     

巧克力起霜研究进展

巧克力起霜导致产品品质下降,成为困扰糖果工业的一个世界性难题。基料油种类不同,起霜的机理显著不同。从基料油性质出发,详细阐述基料油组成、加工条件以及储存条件对巧克力起霜的影响。在此基础上,对各类巧克力起霜的机理进行总结,为解决起霜问题提供理论支持。参考国内外文献报道,对巧克力起霜的研究方法进行总结,并详细阐述具有延缓起霜作用的措施,为巧克力生产提供参考。     

巧克力"起霜"现象的探索

香醇浓郁的巧克随着质量的提高，不断受到人们的欢迎。但在其发生的各种质量问题中，“起霜”现象占的比例最高，对巧克力的影响也是最重要的。如何有效防止起霜是巧克力制造业需待解决问题，该文探讨了巧克力起霜的原因，对起霜巧克力的质地和风味做了感官评定，并提出相应延缓巧克力起霜的方法。     

巧克力"起霜"现象的探讨

香醇浓郁的巧克随着质量的提高，不断受到人们的欢迎。但在其发生的各种质量问题中，“起霜”现象占的比例最高，对巧克力的影响也是最重要的。如何有效防止起霜是巧克力制造业需待解决问题。该文探讨了巧克力“起霜”的原因，对“起霜”巧克力的质地和风昧做了感官评定，并提出相应延缓巧克力“起霜”的方法。     

月桂酸类代可可脂巧克力脂霜组成及形态学研究

通过气相色谱分析和显微镜观察对起霜前后月桂酸类代可可脂巧克力的脂肪酸组成以及形态学特征进行了研究。结果表明,与新鲜巧克力相比,脂霜中C12∶0、C18∶0、C18∶1含量明显增加,而C14∶0含量相对减少;原子力显微镜结果显示,新鲜巧克力表面相对平滑,起霜后平滑表面破坏,形成明显凹凸面;扫描电镜观察发现新鲜巧克力表面结晶网络结构疏松,起霜巧克力表面油脂晶体形成致密网络结构;偏光显微镜显示脂霜中晶体颗粒明显大于新鲜巧克力晶体颗粒,发生了向更稳定晶体的转变。     

香菇、茶叶抗类可可脂巧克力脂霜之形态学研究

用偏光显微镜和扫描电镜在形态学方面就香菇和茶叶抗类可可脂巧克力脂霜进行了研究 ,电镜结果表明 ,香菇和茶叶巧克力的质构呈链状有规则排列 ,而对照样则呈杂乱零星无规则排列。偏光显微结果说明 ,无论是起霜还是未起霜的香菇和茶叶巧克力 ,其晶相均呈有规律的均匀分布 ,而对照样则无规则性可言。在相同的促霜时间内 ,对照样起霜程度比香菇和茶叶巧克力大     

关于巧克力“起霜”现象的研究

巧克力“起霜”现象是食品工业影响巧克力质量的世界性难题，关于它的起因，防止方法历来说法不一。本文从晶型，熔点，ＳＦＩ值，温度等多种角度，全面，系统地分析了“起霜”巧克力与普通巧克力在结构上的根本区别，揭示了巧克力“起霜”现象的根本原因及防止途径。     

调温和油脂组成对巧克力原料油及其应用性能的影响

研究调温和油脂组成对巧克力油脂（可可脂与全氢化棕榈仁油硬脂混合物）的相容性、巧克力的质构以及在20 ℃贮藏3 个月过程中起霜稳定性的影响。结果表明：可可脂与全氢化棕榈仁油硬脂混合物未调温时随可可脂含量增加有明显的稀释作用,经调温后可可脂含量在30%～50%之间出现明显共晶;巧克力硬度受调温和巧克力油脂相容性影响显著。当巧克力油基中可可脂含量＜50%,巧克力硬度随可可脂增加而降低;当可可脂含量＞50%,经调温巧克力硬度显著增加而未经调温巧克力硬度较为恒定。20 ℃贮藏实验发现：未调温,巧克力可可脂含量越高,起霜越显著;调温后,样品可可脂含量在10%～50%范围内起霜程度降低,当可可脂含量＞50%及纯全氢化棕榈仁油硬脂时,产品得到明显改善而无起霜现象。从巧克力的熔化特性和巧克力表层的脂肪酸组成分析发现,当可可脂含量＞50%时,未调温巧克力引起起霜的机制是不稳定晶体向稳定晶体转化;当可可脂含量≤50%时,引起起霜的机制是可可脂与全氢化棕榈仁油硬脂较差的相容性,导致部分油脂迁移至表面重结晶。     

三种巧克力晶型衍变与起霜花关系研究

本文借助X衍射仪对不同促霜时间内不同起霜程度的巧克力进行晶相检测，结果表明晶相衍变速率大小与起霜程度关系紧密，速率大则起霜严重，促霜前期（5天内），巧克力均未起霜，具有相同的晶相，促霜后期（45天），三种巧克力均有不同程度的霜花，其中CC最严重，LC轻微，TC介于两者之间，XRD谱图反映的晶相也说明了这一现象，促霜中期（20天），CC起了霜，而LC和TC尚无起霜迹象，这时CC中的晶相与LC和TC的相比相差很大，LC和TC的晶相则一致。     

巧克力制品起霜原因和预防法

消费群众对巧克力制品质量要求上,最大的意见是起霜问题。巧克力制品(以下简称制品)从表面起白色斑点或有薄薄一层白霜,直到全部变成灰白色,这个过程叫做起霜,或称为“发花”。现将起霜的原因和预防方法,简述如     

Comparison of Whiteness Index vs. Fractal Fourier in the Determination of Bloom Chocolate Using Image Analysis

Modeling of bloom is essential to evaluate the effectiveness of processes in chocolate and to determine its shelf life. Computer vision and the fractal kinetic method were used to quantify bloom in samples of chocolate coating and cocoa chocolate subjected to a 3- or 6-h temperature cycle. Bloom was also determined by classical methods (L* lightness and whiteness index). In the results, the kinetic bloom rate derived by the fractal kinetic method was higher than that obtained with the L* or white index. Fractal method can be used to determine kinetic bloom and to detect differences in chocolate coating affected by 3 or 6 h of temperature cycle. The bloom rate derived by the fractal method was higher that the mean L* value and whiteness index methods; no differences could be registered between the last two methods. In general, the fractal method can be seen as a new means of quantifying bloom in chocolate and allows registering the bloom faster than the L* value and white index methods.     

巧克力“白霜”的解决方案

<正>巧克力风味独特、口感好,颇受人们的喜爱。随着巧克力制品消费量的增加,其质量问题也越来越受到各方的关注。其中巧克力起白霜是巧克力产业的世界性难题。白霜花是指加工、贮存、销售过程中,巧克力表面均一发白(酷似秋霜)或起凹凸不平的花斑点,甚至全部变成灰白色而失去光泽。外观使顾客误以为发霉而令人难以接受。严重时,内部组织呈干砂粒状,失去坚脆、断而有声、入口即化,凉爽润滑、细腻而不糊口等特征, 食似嚼蜡,失去商品价值。     

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.     

乳化性物质与抗巧克力起霜花

叙述了巧克力起霜花的主要影响因素 ,并探讨了具有乳化性能的物质对抗巧克力霜花机理及其对指导抗巧克力霜花的现实意义。     

Influence of lactic acid ester on chocolate quality

Influence of concentration of emulsifier Lactem P 22 (lactic acid ester of monodiglyceride) as blooming inhibitor on the quality and fat bloom stability of laboratory made samples of chocolate was investigated. This ingredient was added during the pre-crystallization process of chocolate mass. The pre-crystallization was performed in the laboratory crystallizer modified Brabender pharinograph, where the rheological characteristics of the pre-crystallized fluid chocolate mass were measured. The experiments were performed according to the factorial plan 3² (two factors on three levels). Statistical results processing was performed according to the Response Surface Methodology. Physics characteristics of chocolate—hardness and lightness—were obtained by instrumental methods. The results has shown that Lactem P 22 improve fat bloom stability of chocolate samples but decrease sensory quality of chocolate. Better sensory quality of chocolate was achieved with combination of the crystallization promoter—Dynasan 118. The best sensory quality of chocolate has been obtained with 0.5% Dynasan 118 and 1 and 2% Lactem P 22. Samples of chocolate which was pre-crystallized on 23°C and with 3% Lactem P 22, showed the highest fat bloom stability.     

The effect of various substances on the blooming of chocolate

Summary. The effects of many edible substances and pure chemicals on chocolate have been studied in relation to the prevention of chocolate blooming. Bile acids, cholesterol, other sterols and choline promoted the blooming of chocolate. Tripalmitin, added in good dispersion, made chocolate very resistant to fat bloom and chocolate had a high gloss. Hydrogenated fats made very difficult temperable chocolate and it had a waxy taste. Only Delft 37 and some Edelfette improved the resistance of chocolate, but they made it waxy. Butylated hydroxyanisole (BHA) has undesirable effects.
Anhydrous glucose added at the rate of 15-20% of the weight of chocolate increased the resistance. Other sugars were either inert or diminished the resistance. Glycerol had a strikingly unfavourable effect on both quality and resistance. Amino acids did not exhibit any special influence on chocolate. Chemical additives and biological treatment also influenced the blooming of milk chocolate. Unusually long bloom crystals were produced on the surface of milk chocolate on special occasions.     

TEXTURAL CHANGES IN CHOCOLATE CHARACTERIZED BY INSTRUMENTAL AND SENSORY TECHNIQUES

Cocoa butter has a distinct texture due to unique interactions of polymorphic lipid structures. Part of chocolate's appeal is smooth mouthfeel; as fat or sugar bloom forms, textural change is perceived. Correlation of instrumental and sensory texture analysis has not been conducted in stored chocolate. The objective of this study was to analyze texture and color of dark and milk chocolate stored under conditions leading to fat and/or sugar bloom by instrumental and sensory measurements. Milk and dark chocolate was stored 5 weeks at various temperatures and relative humidity (RH), followed by instrumental and sensory texture analysis. All attributes, except springiness, were significantly affected by treatments. According to partial least squares linear regression, instrumental hardness, cohesiveness, chewiness and gumminess modeled sensory hardness. The 30.0C incubator experienced temperature fluctuations, resulting in severe fat bloom. Temperature fluctuations during storage had more influence on texture perception than storage at high temperatures or high RH.

PRACTICAL APPLICATIONS

This research serves as an initial study on textural aspects of chocolate quality upon storage that is the first report to correlate instrumental textural analysis of chocolate to sensory evaluation. Storage temperature and humidity of chocolate greatly impacts consumer texture perception, which is valuable information to small chocolate handlers and manufacturers who have noted to us that many of the larger companies may have this information – but it is not widely available. It also sets the stage for more detailed studies on texture and flavor of chocolate during storage. Although many storage studies on chocolate exist, those that intertwine studies of quality from both an instrumental and a sensory standpoint are lacking.     

Surface structure and composition of fresh and bloomed chocolate analysed using X-ray photoelectron spectroscopy, cryo-scanning electron microscopy and environmental scanning electron microscopy

Bloom on chocolate is an unsightly surface condition resulting in a white, powdery appearance that consumers interpret as a sign of poor quality. Bloom results from incorrect processing or storage. Two innovative methods have been developed, and used in conjunction, to investigate the morphology and composition of bloomed chocolate.Environmental scanning electron microscopy (ESEM) was used to image the morphology of the surface of fresh and bloomed chocolate and to observe the changes in morphology, in real time, during heating and cooling. The nodular morphology of sugar bloom was easily distinguished from the blade like crystals of fat bloom. Surface details for the fat blades indicated an extrusion mechanism during their formation on the chocolate surface.“Cold stage” X-Ray Photoelectron Spectroscopy (XPS) was used to analyse the surface composition of fresh and bloomed samples. The carbon species present in the bloom on poorly tempered chocolate were a combination of CH₂, C-OH, OC-OH and O-C-O groups indicating a mixture of sugar and fat bloom. Conversely the species present on bloomed, well tempered chocolate comprised only CH₂, C-OH, OC-OH indicating the bloom was comprised of fat (from cocoa butter) and no sugar.