Fundamental studies on gelation of gelatin obtained from amphibious aquaculture food waste

• Main Author: Chan, Fion Xin Hui
• Other Authors: Tan Lay Poh
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Materials
• Online Access: https://hdl.handle.net/10356/156251
• Institution: Nanyang Technological University

The extraction method of gelatin from American bullfrog (Rana caresbeiana) skins are improved upon to obtain a higher yield percentage. The physical crosslinking and gel properties of 5, 6.67, 7.5, and 10 w/v % of extracted bullfrog gelatin have been investigated. It is found that as gelatin concentration increases, gelation temperature increases while gelation time decreases. A higher concentration of gelatin allows more reformation of tripe helices due to a decrease in distance between polypeptide chains and thus higher probability of reformation. Chemical crosslinking catalysed by microbial transglutaminase (mTgase) has also been investigated, where gel properties were measured. Gelatin concentration of 5, 7.5, and 10 w/v % was varied together with mTgase concentration of 5, 10, and 20 U/g. This was done for temperatures of 25, 30, 37, 40, 50, 60, and 70 °C. From these experiments it was found that a temperature range of 31 – 38 °C is where physical and chemical crosslinking is at its minimum. While a temperature of 51 °C is the optimal working temperature of mTgase. When time sweep was performed for increasing gelatin concentration from 5 to 10 w/v %, a right ward shift in gelation temperature maxima (31 – 38 °C) can be observed. This can be attributed to the increasing number hydrogen bonds in higher gelatin concentration, resulting in a larger amount of energy required to break the higher number of hydrogen bonds between polypeptide chains as gelatin concentration increases. It is also found that the bond between the triple helices in physical crosslinking is weaker than the isopeptide bond in chemical crosslinking. The characterisation of different gelatin concentration, gelling temperatures and mTgase concentrations provides a platform for future research to develop gels of different properties to fit different applications.