巧克力起霜的研究进展

本文根据当今研究进展,阐述了引起巧克力制品起霜的机理,即相态分离理论和多晶态转化理论,针对各种不同的起霜原由,提出不同的有效万法以延缓起霜现象的发生。     

巧克力起霜问题探讨

如何有效防止起霜是巧克力制造业需待解决问题,该文比较全面分析巧克力起霜原因,机理, 并提出相应延缓巧克力起霜方法。     

芒果脂提高巧克力抗霜性的研究

StOSt是芒果脂的特征成分,也是解决巧克力在炎热和冷链缺乏地区软化和起霜问题的关键成分。然而,在应用中发现StOSt虽提高巧克力的耐热性,却可能加速起霜。本文将芒果脂与可可脂复配,制备巧克力油基,分析其甘油酯、甘油三酯组成和熔化行为,进而研究相应巧克力的抗霜性能。结果表明：芒果脂含StOSt 44.7%、低熔点甘油三酯23.9%、甘油二酯8.3%,其中低熔点甘油三酯和甘油二酯含量均显著高于可可脂;其与可可脂复配所得油基的StOSt/POSt/POP比值接近4.0/2.5/1.0且甘油二酯含量为6%~8%时,可延缓油基从V向VI晶型转换,从而提高了所制备巧克力的抗霜性。本文为类似富含StOSt的油脂在抗霜巧克力中的应用提供科学参考。     

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。     

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。     

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。     

乳化剂在巧克力工业中的应用

本文叙述了巧克力起霜的主要影响因素，并探讨了乳化剂应用于巧克力工业中的抗霜机理及其现实意义。     

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。     

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     

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.     

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.     

The role of conching in chocolate flavor development: A review

Chocolate is an indulgent product whose consumption is mostly motivated by its alluring sensory properties. Among them, flavor stands as the key driver for consumer preference and purchase intention. Flavor is a complex multimodal perception whose discrimination depends mostly on the retronasal aromas associated with the presence of odor-active compounds in the matrix. The development of chocolate flavor relies on several factors, ranging from intrinsic properties of raw materials to formulation and processing conditions. As the last step of liquid chocolate manufacture, conching develops proper fluidity/texture and finetunes flavor, by means of intensive mixing and continuous heating of chocolate mass for several hours. Time and temperature are the main parameters determining the extent of conching effects upon flavor, despite factors such as ventilation, energy input onto chocolate mass, and configuration of conching machine being also relevant to some of the physicochemical mechanisms involved in flavor modification. Overall, conching impacts chocolate flavor by either changing the concentration of key odor-active compounds or modifying their distribution throughout the matrix, affecting their binding to other components and, ultimately, their rate of release during ingestion. The present review aims to gather evidence on the physicochemical transformations promoted by conching responsible for flavor enhancement and overall sensory quality of chocolates.     

Fat Migration in Chocolate: Diffusion or Capillary Flow in a Particulate Solid?—A Hypothesis Paper

ABSTRACT: The exact mechanism of fat and oil migration in chocolate and chocolate coatings is still unknown. Nevertheless, the so-called "diffusion equation" derived from Fick's 2nd law has been extensively used to model the phenomenon, giving the impression that molecular diffusion is the single transport mechanism. We propose that chocolate may be microstructurally regarded as a particulate medium formed by an assembly of fat-coated particles (for example, cocoa solids, sugars crystals, and milk powder). Within this matrix the liquid fraction of cocoa fat (which increases with temperature) is likely to move under capillary forces through interparticle passages and connected pores. Based on available evidence (microstructure, kinetic data, temperature dependence of liquid fat fraction, and so on) we demonstrate that capillary forces may have an important role to play in bulk flow of liquid fat and oils. The Lucas-Washburn equation for capillary rise fits available data under most reported experimental conditions. Detailed microstructural analysis in actual products as well as data on key parameters (surface tension, contact angle, viscosity) is necessary to confirm this hypothesis. Bulk flow due to capillary effects, highly disregarded in structured foods, should be considered as a mass transfer mechanism in liquid-filled porous or particulate foods.     

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.     

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.     

齿轮泵在食品工业中的应用

<正>粮食在农夫收割之后,必须经过食品工业的加工才能成为我们口中的食品。食品加工者与制造厂是食品工业的关键组成部分。总的来说,食品加工者离农场最近,并专注于一、两种食物的加工,而大型食品制造厂则是利用已加工好的配料成分来制造产品,很少局限于一类的食品。 泵是食品制造过程中的一个基本组成部分,其基本功能是将流体从一个地方传送到另一个地方。在泵的演变过程中,人们设计出很多类型的泵,以满足不同的应用需求。由于许多食品在流动中出现复杂的不符合牛顿力学的情况,因此食品工业的工程师必须了解不同类型的泵、泵的性能及局限性。     

The Resistance of Quinoa (Chenopodium quinoaWilld.) to Adverse Abiotic Factors

Quinoa (Chenopodium quinoaWilld.) has been cultivated in the Andean region for thousands of years, providing highly nutritious food to poor farmers in the Andes. The conditions for crop growth are very difficult in the high region of the Andes, where the most harmful abiotic adverse factors that affect crop production are drought, frost, soil salinity, hail, snow, wind, flooding, and heat.

Quinoa can grow with only 200 mm of rainfall in pure sand. Fourteen lines with improved drought resistance have been identified, and several drought-mediating mechanisms have been found. The crop has also demonstrated unusually high salt tolerance; many varieties can grow in salt concentrations as high as those found in seawater (40 mS cm^-1), and four lines have been identified with even higher tolerance. Quinoa also has a high degree of frost resistance, surviving -8°C for up to 4 hours, depending on phenological phase and variety.     

Effect of nut oil migration on polymorphic transformation in a model system

Fat migration in confectionery products can lead to significant deterioration in quality. This occurs not only through loss in texture contrast between chocolate and filling but also through the appearance of fat bloom on the surface of the chocolate. This latter aspect is often, although not exclusively, linked to the transformation of the cocoa butter β_V phase into β_VI. In this study, the influence of hazelnut oil on the polymorphic transformation of cocoa butter has been determined, showing that even small additions (1%) of nut oil can have a significant impact on the rate of transformation. Additionally, use of a model system has shown that polymorphic transformation in cocoa butter is linked to the degree of migration of nut oil from a filling. Portions of the cocoa butter close to the filling experience both greater degrees of migration and faster transformation.