Location: Healthy Processed Foods ResearchTitle: Effect of transglutaminase crosslinking on solubility property and mechanical strength of gelatin-zein nanocomposite films
|AHAMMED, SHABBIR - Jiangnan University|
|LIU, FEI - Jiangnan University|
|WU, JINGMIN - Jiangnan University|
|KHIN, MYAT NOE - Jiangnan University|
|Yokoyama, Wallace - Wally|
|ZHONG, FANG - Jiangnan University|
Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2021
Publication Date: 2/3/2021
Publication URL: https://handle.nal.usda.gov/10113/7266460
Citation: Ahammed, S., Liu, F., Wu, J., Khin, M., Yokoyama, W.H., Zhong, F. 2021. Effect of transglutaminase crosslinking on solubility property and mechanical strength of gelatin-zein nanocomposite films. Food Hydrocolloids. 116. Article 106649. https://doi.org/10.1016/j.foodhyd.2021.106649.
Interpretive Summary: Pollution by plastics are a global problem. The research describes the development of a biodegradable and edible film from the proteins, gelatin and zein. While gelatin has superior mechanical strength and transparency, it is water soluble and loses its strength in contact with moisture. Zein is insoluble but has poor mechanical properties. Combining the two proteins is difficult due to their incompatible solubility properties. An enzyme, transglutaminase, was used to covalently bond a mixture of the two proteins together to form a matrix that had good mechanical properties and was insoluble in water.
Technical Abstract: The solubility (WS) of gelatin films in water limits its packaging application of high moisture content foods. Crosslinking by transglutaminase (TGase) and addition of zein were reported to reduce WS of gelatin films, but it is a challenge to incorporate TGase in a system of two immiscible materials of gelatin (water soluble) and zein (ethanol soluble) as well as in the environment of low pH when aqueous acetic acid is used to as a commonly used solvent. Zein in ethanol was added to gelatin in aqueous solution at a controlled rate. the final concentration of ethanol was 8.5% and this film forming solution provided the optimal pH for TGase while keeping both proteins soluble. Crosslinking was confirmed by the formation of higher molecular weight protein in SDS-PAGE. The optimum crosslinking degree (65%) was with 95% gelatin/5% zein. Tensile strength of the TGase treated films was improved from 5 to 36 times and proportional to the gelatin-zein crosslinking degree, while water solubility (~98% insoluble in water) depended on the type of crosslinking. The presence of zein improved the thermal properties (melting temperature up to 19 degrees celsius) but reduced the transparency as compare to pure gelatin film. TGase modified gelatin/zein composite films with improved water insolubility, water vaper permeability and mechanical properties are potential candidates for high moisture food packaging application.