Abstract:To comprehensively utilize blood by-products from the livestock and poultry slaughter industries, reduce resource waste, and avoid environmental pollution, pig blood was collected as raw material and the effects of different drying methods on the physicochemical properties of blood serum were investigated. Protein patterns in blood serum, rehydration ratios, soluble-peptide content, degree of hydrolysis, and color of serum powder were adopted as indices, and the effects of vacuum, forced-air, and freeze drying on these indices were investigated and compared. The results indicated that freeze and forced-air drying altered the protein patterns in serum, with minor accumulations of new proteins at molecular weights between 50 ku and 75 ku. Vacuum drying resulted in serum-protein polymerization, producing additional protein species at molecular weights>100 ku. The ability to rehydrate for freeze dried serum powder was better than that of vacuum and forced-air drying samples. Freezed-dried serum powder was dissolved completely in deionized water after 2 h, whereas forced-air and vacuum-dried samples were partially dissolved in deionized water. The soluble-peptide content and degree of hydrolysis of the freeze-dried serum were significantly (p<0.05) higher than those observed in forced-air and vacuum-dried serums. Additionally, the soluble-peptide content and degree of hydrolysis of the forced-air dried serum was significantly (p<0.05) higher than that observed in the vacuum-dried serum, and the color value of the freeze-dried serum was significantly (p<0.05) higher than that observed for the forced-air dried and vacuum dried serums.
