Location: Healthy Processed Foods ResearchTitle: Tailoring physical properties of transglutaminase-modified gelatin films by varying drying temperature
|LIU, FEI - Jiangnan University|
|ANTONIOU, JOHN - Jiangnan University|
|LI, YUE - Jiangnan University|
|MA, YUN - Jiangnan University|
|MA, JIANGUO - Jiangnan University|
|Yokoyama, Wallace - Wally|
|ZHONG, FANG - Jiangnan University|
Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2016
Publication Date: 2/22/2016
Citation: Liu, F., Antoniou, J., Li, Y., Ma, Y., Ma, J., Yokoyama, W.H., Zhong, F. 2016. Tailoring physical properties of transglutaminase-modified gelatin films by varying drying temperature. Food Hydrocolloids. 58:20-28.
Interpretive Summary: Gelatin films suffer from brittleness and water solubility. Gelatin, like other proteins, can be crosslinked by the enzyme transglutaminase. Cross-linking improves strength and decreases water solubility of gelatin films. Gelatin protein can have different conformations. In its natural state the triple helix conformation is often favored. Low drying temperatures favor the formation of triple helix conformation. Drying at lower temperatures also increases film tensile strength.
Technical Abstract: Gelatin films prepared with or without transglutaminase (TGase) and dried at 15, 25 and 35 °C were analyzed for polymeric network structure, chemical composition and physical properties. Differences in protein network structure were observed by optical microscopy analysis in freeze-dried film-forming solutions incubated at different temperatures for 6 h. A combination of X-ray diffraction (XRD) and differential scanning calorimetry (DSC) showed that the relative amount of triple helices decreased as drying temperature increased and the addition of TGase slightly inhibited triple helices formation. TGase modification enhanced the thermal stability of gelatin films by increasing the glass transition temperature and degradation temperature, which was further enhanced with increasing drying temperature. The change trend of mechanical properties between blank and TGase-modified films were similar but the TGase-modified films exhibited stronger mechanical properties; the highest tensile strength was observed in films dried at 25 °C and highest elongation at break at 35 °C. When TGase was added, water solubility was reduced from 100% to around 35% and decreased slightly at higher drying temperatures. Moreover, upon addition of TGase, the cross-section (SEM) and surface (AFM) of gelatin films appeared more compact and smoother and these characteristics improved when temperature increased. It is observed that physical properties of TGase-modified gelatin films could be modulated by varying the relative amount of triple helices and covalent bonds, which in turn could be controlled by varying the drying temperature.