Effect of different phenolic compounds and extracts oxidized by laccase on properties of gelatin gel
The gelatin solution (6.67%) was prepared as per the method of Nagarajan et al. (2013). To the solution, commercial phenolic compounds (catechin, ferulic acid, tannic acid and gallic acid) or the extracts, EKWE and ECBE, were added to obtain the concentration of 2% (w/w, based on gelatin). Thereafter, laccase (20 U/mL) was added and mixed well. The prepared solutions were placed in a temperature-controlled water bath (40°C) and subjected to oxygenation for 30
min by bubbling the solution with oxygen to convert the phenolic compounds to quinone. The mixtures Temdee and Benjakul /IFRJ 22(1): 246-253 248were further stirred for 1 h at room temperature (25-27oC). The obtained gelatin solution was then used for gel preparation and analyses. The control gelatin solution (6.67%) was also prepared without the addition of phenolic compounds or the extracts.