棕榈油和无水乳脂混合物的脂肪结晶：静态和动态结晶之间的比较,Food Research International

动态结晶（剪切与快速冷却的结合）的应用通常在起酥油/人造黄油等工业脂肪基产品的生产中起重要作用，但鲜有报道。在这项研究中，将棕榈油（PO）与无水乳脂（AMF）（0、25和50％AMF，w / w）的三种混合物在静态（使用冰箱）和动态条件下（使用台式刮擦表面）快速结晶。热交换器）。应用了多种技术，包括差示扫描量热法（DSC），X射线衍射（XRD），偏振光显微镜（PLM），流变学和质构分析，以研究脂肪混合物的理化性质以及长期储存后的晶体形态（4周）在5°C和15°C下。结果表明，动态结晶的高冷却速率不仅影响脂肪共混物的熔融行为，而且还阻止了从β'到β晶体的多晶型转变。此外，在脂肪结晶过程中施加剪切力有助于显着提高产生的起酥油的凝胶强度。尽管所有在5°C下储存的起酥油都发生了低熔点三酰基甘油（TAG）的后结晶，并伴随着硬度的增加，但对于拥有较高AMF含量的样品而言，它的作用更为可观。此外，该现象促进了动态结晶的脂肪共混物的脂肪晶体之间的烧结以及奥斯特瓦尔德熟化，导致形成了尺寸在100至500μm之间的多余的大聚集体（或颗粒状晶体）。

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The application of dynamic-crystallization (a combination of shear with rapid cooling) often plays an important role in the production of industrial fat-based products such as shortenings/margarines but has been rarely reported. In this study, three blends of palm oil (PO) with anhydrous milk fat (AMF) (0, 25 and 50% AMF, w/w) were rapidly crystallized under static (using freezer) and dynamic conditions (using a benchtop scraped surface heat exchanger). Various techniques including differential scanning calorimetry (DSC), X-ray diffraction (XRD), polarized light microscopy (PLM), rheology and texture analysis were applied to investigate physicochemical properties of fat blends as well as their crystal morphology upon the long-term storage (4 weeks) at 5 °C and 15 °C. The results revealed that high cooling rate of dynamic-crystallization not only affected melting behavior of fat blends but also prevented the polymorphic transformation from β’ to β crystals. Besides, the application of shear during fat crystallization helped to improve significantly the gel strength of produced shortenings. Although post-crystallization of low melting triacylglycerols (TAGs) occurred for all produced shortenings during storage at 5 °C which was accompanying with a firmness increase, it was more considerable for samples owning higher AMF content. Moreover, this phenomenon promoted the sintering as well as Ostwald ripening between fat crystals of dynamic-crystallized fat blends resulting in the formation of unwanted large aggregates (or granular crystals) with the size ranging from 100 to 500 μm.