Upcycling calf cruor slaughterhouse by-product by peptic hydrolysis and identification of three novel antifungal peptides following a regression based-machine learning approach

• Hydrolysis of Calf-cruor followed the same enzymatic mechanisms as adult bovine hemoglobin. • Peptic hydrolysis of Calf-cruor at pH 2 and pH 3 for 180 min promoted antibacterial activity. • Peptic hydrolysis of Calf-cruor at pH 3 for 30 min promoted antifungal activity. • PLS-DA allowed the identification of antimicrobial peptides from complex solutions. • Three new antifungal peptide sequences α(47–80), β(130–145), and β(102–109) were identified. Calf cruor (C-cru) is an understudied source of antimicrobial peptides that can be used for meat product biopreservation under a circular economy framework. This study assessed the impact of pH and peptic hydrolysis duration of C-cru on the enzymatic mechanism, peptide population, and antimicrobial activities (antibacterial, antifungal, and anti-yeast). The results showed that peptic hydrolysis of C-cru has similar enzymatic mechanisms to adult bovine hemoglobin, fostering the development of a zipper mechanism at pH 2 and 3, while the one-by-one mechanism is promoted at pH 4 and 5. The antimicrobial activities suggested that peptic hydrolysis at pH 2 and 3 for 180 min fostered higher antibacterial activity, while peptic hydrolysis at pH 3 for 30 min favored both antifungal and anti-yeast activities. Furthermore, a supervised machine learning tool was applied for the first time to peptidomic data enabling the elucidation of α(47–80), β(130–145), and β(102–109) as new antifungal peptide sequences.