胶原明胶化过程中分子结构的变化

本试验以猪皮胶原为原料,研究胶原明胶化过程微观结构的变化规律。研究表明,8 h的酸处理诱导下,胶原明胶化程度较高,热水提胶后明胶得率可达83.98%,随着酸处理时间进一步延长,明胶得率显著下降;差示量热扫描(DSC)、红外光谱(FTIR)和圆二色谱(CD)研究表明,随酸处理的进行,胶原的三螺旋结构逐渐松散,维系三螺旋结构稳定的价键逐渐被破坏,酸处理8 h后,胶原三螺旋结构被过度破坏,是导致明胶得率降低的主要原因。聚丙烯酰胺凝胶电泳(SDS-PAGE)分析显示,在酸处理的过程中,胶原肽链的降解始终存在,且明胶化胶原中所保留的亚基量直接影响明胶中亚基含量。因此,在明胶化过程中必须在肽链降解和三螺旋结构松散之间寻找平衡点,以获得高得率和高品质明胶。

Changes in Molecular Structure of Collagen during Gelatinization

The microstructure of collagen from pig skin was studied during gelatinization. The results showed that a relatively high degree of gelatinization of collagen was achieved after 8-h acid treatment and the yield of gelatin reached 83.98% after hot water extraction, while the yield of gelatin dropped significantly with increasing duration of acid treatment. The results from differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), and circular dichroism (CD) revealed that the triple-helical structure of collagen became progressively loose and valence bonds stabilizing the triple-helix were gradually destroyed during the process of acid treatment. The triple-helical structure was excessively destroyed after 8-h acid treatment, which could be the main reason for the decrease in gelatin yield. Moreover, the results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) indicated that collagen peptide chains were degraded during acid treatment and the gelatin subunit content was directly influenced by the amount of subunits that remained after gelatinization. Therefore, during the gelatinization of collagen, a balance between subunit degradation and the loosening of the triple-helical structure is required, in order to obtain high yield of high-quality gelatin.