This study presents the production of a novel natural blue colorant obtained from the cross-linking between milk proteins and genipin assisted by low-frequency and high-power ultrasound technology. Genipin was extracted from unripe Genipa americana L. using milk as a solvent. Also, milk colloidal system was used as a reaction medium and carrier for the blue color compounds. The effects of ultrasound nominal power (100, 200, 300, and 400 W) on the blue color formation kinetics in milk samples were evaluated at 2, 24, and 48 h of cold storage in relation to their free-genipin content and color parameters. In addition, Fourier transform infrared (FTIR) spectrum, droplet size distribution, microstructure, and kinetic stability of the blue colorant-loaded milk samples were assessed. Our results have demonstrated that the ultrasound technology was a promising and efficient technique to obtain blue colorant-loaded milk samples. One-step acoustic cavitation assisted the genipin extraction and its diffusion into the milk colloidal system favoring its cross-linking with milk proteins. Ultrasound process intensification by increasing the nominal power promoted higher genipin recovery resulting in bluer milk samples. However, the application of high temperatures associated with intensified acoustic cavitation processing favored the occurrence of non-enzymatic browning due to the formation of complex melanin substances from the Maillard reaction. Also, the blue milk samples were chemically stable since their functional groups were not modified after ultrasound processing. Likewise, all blue colorant-loaded milk samples were kinetically stable during their cold storage. Therefore, a novel natural blue colorant with high-potential application in food products like ice creams, dairy beverages, bakery products, and candies was produced.

中文翻译：

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低频和高功率超声辅助从牛奶和未成熟的美洲Gen鱼生产天然蓝色色素。

这项研究提出了一种新型的天然蓝色着色剂的生产，该着色剂是在低频和高功率超声技术的辅助下，通过乳蛋白和京尼平之间的交联而获得的。Genipin是使用牛奶作为溶剂从未成熟的Genipa americana L.中提取的。另外，乳胶体系统用作蓝色化合物的反应介质和载体。超声标称功率（100、200、300和400 W）对牛奶样品中蓝色形成动力学的影响是在冷藏2小时，24小时和48小时时评估的，其游离京尼平含量和颜色参数有关。此外，还对装载蓝色着色剂的牛奶样品的傅里叶变换红外（FTIR）光谱，液滴尺寸分布，微观结构和动力学稳定性进行了评估。我们的结果表明，超声技术是一种获得载有蓝色着色剂的牛奶样品的有前途且有效的技术。一步声空化有助于京尼平的提取及其向乳胶系统中的扩散，有利于其与乳蛋白的交联。通过增加标称功率来加强超声过程可促进更高的Genipin回收率，从而使牛奶样品更蓝。然而，由于美拉德反应形成了复杂的黑色素物质，因此伴随着增强的声空化处理的高温应用促进了非酶褐变的发生。而且，由于在超声处理后它们的官能团没有被修饰，因此蓝奶样品是化学稳定的。同样 所有装载蓝色着色剂的牛奶样品在冷藏期间均保持动力学稳定。因此，产生了在食品如冰淇淋，乳制品饮料，烘焙产品和糖果中具有高潜力应用的新型天然蓝色着色剂。