3.3.Physicochemical analysis.
Data presented in table 7 show the pH values and
water activity (a
) of FF and LF mayonnaise. The pH
values of LF mayonnaise were significantly (P≤0.05)
higher than that of FF mayonnaise. Increasing the
level of fat substitution in mayonnaise formulations
resulted in significant (P≤0.05) increases in the pH
values. The increases in pH values might be due to
the dilution of acetic acid in the aqueous phase of the
LF formulations since there were significant (P≤0.05)
increases in the moisture content as the level of fat
w
substitution increased (table 6). These results are in
good agreement with those obtained by [Hathcox,
Beuchat [16], Karas, Skvarca [17]]. Radford and
Board [18] recommended the use of vinegar as
acidulant to achieve a pH of 4.1 or less as a major
inhibitory substance against microorganisms. Smittle
[19] also suggested that the pH of mayonnaise should
be 4.1 or less to maintain a product free from
Salmonella. From the microbiological safety point of
view, it is important to note that the pH values of the
mayonnaise in the current study ranged from 3.34 to
3.38.