Biologically active peptides from milk whey, such as caseinomacropeptide (CMP), are of great interest for food technology and for the development of new functional foods. CMP is the soluble derivative of k-casein, generated by the cleavage of the enzyme chymosin enzyme in manufacture of cheese. The objective of this work was to isolate the CMP from whey by ultrafiltration, to determine the physical-chemical composition and to characterize it by high performance liquid chromatography (HPLC). The method applied was the ultrafiltration membrane 50, 30 and 5 kDa. The fraction of CMP isolated consisted of 73.7% protein content, 12% lactose and 2.5% sialic acid. The end fractions of the isolation presented chromatographic profiles compatible with CMP. Process parameters and characteristics of the raw material can change the efficiency of CMP isolation. Therefore, it is important to optimize all process step parameters for efficient isolation.

Caseinomacropeptide (CMP) is derived from the chymosin cleavage of κ-casein during cheese production. This study developed gels from CMPs, which were isolated by different ultrafiltration systems, and whey protein isolate (WPI), and studied their rheological and ultrastructural characteristics. The 30% WPI gel showed high elastic modulus (G′) values and stronger structure than the other samples with CMP. Another gel, with 50% protein, 30% WPI and 20% CMP sample isolated from the 30 kDa retentate, had a weaker structure and lower G′ value. The third gel, with 30% WPI and 20% CMP sample from the 5 kDa retentate derived from the 30 kDa retentate, presented intermediate structural strength. Despite the increase in protein concentration from the addition of CMP, there was a decrease in the strength of the gel network. Different CMP isolation processes also contributed to differences in the microscopic analysis of gel structures with the same protein content.