Stock solutions of 1 mg/ml of both MNEI and Y65R were prepared
by dissolving each protein in mineral water, pH 6.8. In order to
determine the detection threshold (DT) and recognition threshold
(RT), nine concentrations of each protein obtained from stock solution,
going from 0.49 mg/l to 5.32 mg/l, were prepared. The range of
concentrations was chosen on the basis of the results from previous
research. Two different
pH conditions were investigated: 6.8 and 5.1. Citric acid powder
(‘‘J.T. Baker’’, 1995, Denveter, Holland) was used as an acidifying
agent in both protein solutions at a concentration of 19 mg/l to reach
a pH equal to 5.1. A modified version of the ‘‘difference from the
reference’’ method was used to determine DT and RT of the proteins,
as previously reported. Thirteen assessors
participated in the study; they were selected for having the same