Comparisons of emulsifying properties of Maillard reaction products conjugated by green, red seaweeds and various commercial proteins

Conjugates were prepared with seaweeds and commercial proteins at 60 °C for 24 h. Bradford protein analysis, SDS–polyacrylamide gel electrophoresis, water absorption capacity, oil absorption capacity, foaming capacity and emulsion activity index/emulsion stability index for seaweeds, commercial proteins and their conjugates were examined. Band patterns with molecule weight ranged from 31 kDa to 116 kDa for conjugates disappeared on the SDS–PAGE. Protein contents measured with the Bradford assay were 0.05–0.12 g/g for conjugates, while measurements for commercial proteins were 0.57–0.90 g/g. Red seaweed and its conjugates showed significantly higher water absorption capacities than those found in other samples, and measurements were 13.03–20.00 ml/g. However, oil absorption capacities of conjugates were lower than commercial proteins. At the foaming initial stage, red seaweed conjugates demonstrated higher foaming capacity than those of commercial proteins and red seaweeds. Conjugates showed higher emulsion activity index than those for seaweeds. Nonetheless, seaweed–protein mixtures showed significantly lower emulsion activity index values than those of commercial and conjugates. The highest emulsion stability indexes were conjugated samples of green seaweed–soy protein isolates and green seaweed–soy protein concentrates which values were 0.977 and 0.919, respectively.