Abstract
The effects of salt and mustard on egg yolk protein hydrolysis in mayonnaise during preservation were investigated. Both the amount of liberated tyrosine and changes in the band around 200kDa on SDS-PAGE decreased with increasing concentration of salt during mayonnaise preservation. Egg yolk aspartic proteinase activity was activated at 1.0 to 3.0% (w/v) NaCl when a synthetic fluorogenic substrate was employed as a substrate. Proteinase activity was confirmed in the mustard water-soluble extract, with maximal activity at pH 4.5. The amount of tyrosine liberated during mayonnaise preservation increased with addition of mustard powder. The hydrolysis of egg yolk protein in the 0.8% (w/w) mustard sample was restricted by adding salt at 2% (w/w), but tyrosine liberated from samples preserved at 5°C for 5wk and at 20°C for 5d were to approximately 45% and 39% that of the non-salt-containing sample, respectively.
