Food & Nutrition

Arab Journal of Food & Nutrition
28. A Study on the Use of Yeasts in the Production of Fermented Cucumbers
(1998)
Saddam Sh. Awaisheh
Supervisor: Dr. Mohammed Isam Yamani
Yeast counts of 13 samples of locally fermented cucumber ranged from 4 x 10 4
to 7 x 10 6 CFU/ml with an average of 5 x 10 5 . The yeast flora belonged to the
following species (in order of occurrence) Saccharomycopsis lipolytica;
Saccharomyces cerevisiae; Debaryomyces hansenii, Cryptococcus humicolus;
Cantdida cantarelli; Cr. laurentii; Ca. diddensiae; Cr. albidus var. aerius; Cr. albidus
var. albidus, Hanseniaspora osmophilla; Hansenula anomala; Pichia fermentans; and
Rhodotorula glutinis.
The most three predominant yeast species were chosen to be used as a starter
culture in cucumber fermentation. Cucumber fermentation with Lactobacillus
plantarum, isolated from a sample of good quality fermented cucumbers, with the
addition of potassium sorbate (0.1%), and naturally fermented cucumbers with the
same concentration of potassium sorbate were used as control, to compare between
cucumber yeast fermentation and cucumber lactic acid bacteria fermentation (LAB).
The brines of yeast fermentation were buffered to pH 3.5 by acetate and acetic acid
(acetate buffer).
Three common characteristic points could be noticed in the cucumber
fermentation in which single yeast cultures were used as a starter culture. These are
related to the changes in the yeast counts, in the pH, and in LAB counts. The changes
in the counts of De. hansenii, Sacch. cerevisiae, and Sacch. lipolytica were small
when compared to the changes in LAB counts of natural fermentation. Little changes
in pH were noticed. The third characteristic of this cucumber yeast fermentation is the
significant increase in the counts of LAB, even though the starting pH of the brines
was 3.5. This low pH was not enough to completely inhibit LAB, although it could
decrease LAB yield when compared to the natural cucumber fermentation. The
increase in LAB count may be explained by the fact that some LAB are able to grow at
low pH as low as 3.5.
The pattern of L. plantarum and single yeast cultures cucumber fermentations
was similar to the pattern of L. plantarum cucumber fermentation and the pattern of
single yeast cultures fermentation, when these are accompanied together.
Most of single yeast cultures cucumber fermentation and L. plantarum with
single yeast cultures cucumber fermentation resulted in fermented cucumbers with
higher overall acceptability over the naturally fermented cucumbers and those
fermentations in which potassium sorbate and/or L. plantarum were used. The positive
effect, imparted by yeasts on the fermented cucumbers may be due to yeast ability to
produce many end products (flavor compounds) from sugar utilization, other than
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Volume 11, No. 25, 2011