tannic acid is a complexed phenol with several hydroxyl groups per
one molecule (Van Buren&Robinson, 1969), it could cross-link
gelatin chains to form strong network. However, under the condition for electrophoresis, SDS was able to destroy those weak bonds.
As a consequence, there was no marked difference in protein patterns among gelatin gel added without and with EECH, particularly
at levels below 1 mg g
1
dry gelatin. Nevertheless, phenolics could
be partially oxidized to some extent during preparation, in which
some quinones were formed. Those might induce the cross-link
formation via covalent bond as evidenced by the slight decrease
in protein band intensity determined by SDS-PAGE. Phenolic
compounds have been oxidized under alkaline condition in the
presence of oxygen (Strauss&Gibson, 2004). The quinone formed
could induce the cross-linking of proteins such as gelatin (Temdee
&Benjakul, 2014) or surimi (Balange&Benjakul, 2009). To shorten
the preparation process and to reduce chemical used, the use of
EECH without oxidation process could be a better choice for
application, especially for human consumption.