Effects of Molecular Weight of Added Collagen-Peptide from Porcine Skin on Rheological and Thermal Properties of Agar Gels

Since collagen-peptide (CP) is composed of peptide chains and fragments with different molecular weights, the rheological and thermal properties of CP must depend on not only amino acid composition but also molecular weight (Mw). Therefore, in the present study, we investigated the effects of the molecular weight of added CP on agar gels using four kinds of CP from porcine skin with Mw=1.1×103, 1.9×103, 5.4×103 and 1.0×104 (CP1000, CP2000, CP5000 and CP10000, respectively). Measurement methods included gel permeation chromatography [GPC], dynamic viscoelastic measurement, rupture properties, syneresis, liquid chromatography mass spectrometry [LC/MS] and differential scanning calorimetry [DSC]. Results showed that for CP1000, rupture stress and Young's modulus increased slightly, and syneresis was inhibited at high density. Since the results of CP2000 differed from CP1000 for rupture properties, it was suggested that ingredients with higher molecular weight influenced rheological and thermal properties of agar gels. On the other hand, it was suggested that ingredients with low molecular weight influenced syneresis, since the results of CP2000 were similar to CP1000. Because the results for CP5000 and CP10000 significantly differed from those for CP1000 and CP2000, it was suggested that ingredients with higher molecular weight influenced agar gels and their ingredients hindered the cross-linking formation.