Teagasc Food Research Centre, Moorepark, Fermoy, P61 C996 Cork, Ireland; VetCORE-Facility for Research Vienna, University of Veterinary Medicine, 1210 Vienna, Austria.
VetCORE-Facility for Research Vienna, University of Veterinary Medicine, 1210 Vienna, Austria.
J Dairy Sci. 2022 Nov;105(12):9387-9403. doi: 10.3168/jds.2022-22048. Epub 2022 Oct 4.
This study explored the use of X-ray computerized microtomography (micro-CT) and confocal Raman microscopy to provide complementary information to well-established techniques, such as confocal laser scanning microscopy (CLSM), for the microstructural characterization of cheese. To evaluate the potential of these techniques, 5 commercial Cheddar cheese samples, 3 with different ripening times and 2 with different fat contents, were analyzed. Confocal laser scanning microscopy was particularly useful to describe differences in fat and protein distribution, especially between the 2 samples with different fat contents. The quantitative data obtained through image analysis correlated well with the nutritional information provided in the product labels. Conversely, micro-CT was more advantageous for studying the size and spatial distribution of microcrystals present within the cheese matrix. Two types of microcrystals were identified that differed in size, shape, and X-ray attenuation. The smallest, with a diameter of approximately 10 to 20 μm, were more abundant in the samples and presented a more uniform roundish shape and higher X-ray attenuation. Larger and more heterogeneous crystals with diameters reaching 50 μm were also observed in scarcer numbers and showed lower X-ray attenuation. Confocal Raman microscopy was useful not only for identifying the distribution of all these components but also allowed comparing the presence of micronutrients such as carotenoids in the cheeses and provided compositional information on the crystals detected. Small and large crystals were identified as calcium phosphate and calcium lactate, respectively. Overall, using micro-CT, confocal Raman microscopy, and CLSM in combination generated novel and complementary information for the microstructural and nutritional characterization of Cheddar cheese. These techniques can be used to provide valuable knowledge when studying the effect of milk composition, processing, and maturation on the cheese quality attributes.
本研究探索了使用 X 射线计算机微断层扫描（微 CT）和共焦拉曼显微镜为成熟奶酪的微观结构特性提供补充信息，这些信息可与共聚焦激光扫描显微镜（CLSM）等成熟技术相结合。为了评估这些技术的潜力，分析了 5 种商业切达奶酪样品，其中 3 种具有不同的成熟时间，2 种具有不同的脂肪含量。共聚焦激光扫描显微镜特别有助于描述脂肪和蛋白质分布的差异，尤其是在两种脂肪含量不同的样品之间。通过图像分析获得的定量数据与产品标签中提供的营养信息密切相关。相比之下，微 CT 更有利于研究奶酪基质中存在的微晶的大小和空间分布。鉴定出两种类型的微晶，它们在大小、形状和 X 射线衰减方面存在差异。直径约为 10 至 20 μm 的最小微晶在样品中更为丰富，呈现出更均匀的圆形形状和更高的 X 射线衰减。直径达到 50 μm 的较大且更不均匀的晶体也观察到数量较少，并且 X 射线衰减较低。共焦拉曼显微镜不仅可用于识别所有这些成分的分布，还可比较奶酪中类胡萝卜素等微量营养素的存在情况，并提供所检测晶体的组成信息。小晶体和大晶体分别鉴定为磷酸钙和乳酸钙。总的来说，使用微 CT、共焦拉曼显微镜和 CLSM 组合生成了切达奶酪微观和营养特性的新颖且互补的信息。这些技术可用于研究牛奶成分、加工和成熟对奶酪质量属性的影响时提供有价值的知识。
