This chapter provides a detailed description of the phenomenon of enzymatic hydrolysis of proteins by exposing the most used techniques to evaluate the rise of the reaction, among which the versatility of the pH-stat method is highlighted. In this chapter, a topic regarding the applications in bovine blood enzymatic hydrolysis is presented, considering that it is a by-product with worldwide dumping problems, and with a great potential to obtain antioxidant and antihypertensive peptides. These effects have been related, for example, to the presence of hydrophobic amino acids and their support in improving the accessibility of compounds in cell matrices. Analysis of molecular interaction mechanisms has allowed clarification of several aspects related to the reasons for bioactive effects. Undoubtedly, the bioactive peptides represent an opportunity for the development of safe treatment alternatives against some diseases, and a substantial support in the design of functional foods. This motivates the development of research in this field and the use of strategies that prioritize the use of byproducts as an important source of bioactive peptides.