Saparbekova A., Sarsekova F, Konarbaeva Z
M. Auezov South-
Kazakhstan State University, Shymkent
Select of leaven strains
for the development the Kazakh national dairy product
People still consume traditional Kazakh dairy products when they are available.
The supply is usually seasonal and prices are high. Kumys and shubat are
the main liquid and qurt the main dry traditional products. There are no
reliable statistics for shubat,
kumys and qurt, as large parts are sold through informal channels. Kumis
is a product of lactic and ethanol fermentations of mare's milk under the
influence of special ferment. As a result of fermentation the drink is slightly
foaming dairy color, freshening, slightly inebriant, sweetish-sour taste and
original aroma turns out [1].
Lactic acid bacteria for a long time have been applied
as starter cultures in fermented foods and beverages, because they can improve
nutritional, organoleptic, technological and shelf-life characteristics. Yeasts are involved in a wide
range of fermented traditional foods and beverages, and contribute to the
sensory properties that are the result of combined metabolic activity of single
strains or microbial groups together with process characteristics. The presence
of yeasts, particularly in dairy products, offers potential advantages due to
the production of flavour components and/or acceleration of ripening, by
metabolizing milk constituents. Yeasts are believed to be essential in the
production of some fermented milks, as Kefir, Kumis, Kurt [2,3].
Five
strain Torulopsis sphaerica, two strains Torulopsis kefir var. kumis and one
strain Candida mycoderma having strong antagonistic properties against bacteria
were found.
Analysis of the active of strains shows that all 8 kind of
yeast strains have more or less high antagonistic activity against the test
bacteria. The most active show five strains of Torulopsis sphaerica (L 5, TR 3
, Zh 2 , Sh 5, K1).
For the development of the kumis leaven from 8
active strains only 1 strains were selected : Torulopsis sphaerica TR 3 having
high antagonistic activity tabl 1.
Table 1 - Antagonistic activity yeast kumis to saprophytic
conditionally-pathogenic and pathogenic bacteria
|
Kind and strains of yeast |
Sarcina flava |
Bac. mycoides |
E. coli |
Proteus vulgaris |
S. abortus ovis |
S.t yphimurium |
S. dublin |
S. gallinarum |
P. multocida |
E. rhusiophatiae |
C. faetus |
Bac. anthracis |
||||||
|
T. sphaerica L 5 |
2 |
3 |
6 |
7 |
11 |
12 |
13 |
14 |
15 |
17 |
18 |
19 |
||||||
|
T. sphaerica TR 3 |
22 |
25 |
25 |
22 |
25 |
20 |
20 |
22 |
16 |
20 |
20 |
18 |
||||||
|
T.
sphaerica Zh 2 |
22 |
25 |
20 |
20 |
18 |
15 |
14 |
15 |
13 |
18 |
14 |
16 |
||||||
|
T. sphaerica Sh 5 |
18 |
25 |
22 |
18 |
13 |
13 |
13 |
13 |
13 |
14 |
13 |
13 |
||||||
|
T.
sphaerica K1 |
19 |
14 |
14 |
20 |
18 |
18 |
16 |
18 |
14 |
18 |
14 |
14 |
||||||
T.kefir var.kumis Kz 4
|
18 |
20 |
21 |
23 |
23 |
20 |
24 |
20 |
16 |
20 |
18 |
16 |
||||||
|
T.kefir var.kumis Lg 3 |
13 |
18 |
18 |
15 |
16 |
14 |
14 |
12 |
12 |
14 |
13 |
12 |
||||||
C.mycoderma: Kz 8
|
23 |
20 |
18 |
19 |
25 |
19 |
19 |
18 |
18 |
20 |
17 |
16 |
||||||
Microbial association of lactic acid bacteria and yeast was used as a more effective an antagonist. Co- culture
of bacteria Lb. acidophilus, Str. lactis
and yeast Torulopsis sphaerica
combines characteristics of its individual components. Based on the
materials obtained during the experiments we can confirm
that the antagonistic properties of lactic acid bacteria associated with many
metabolites, including organic acids. Among the organic acid which more toxic
to microorganisms is acetic, despite the fact that it is of a smaller
proportion than lactic acid. In a number of metabolites of lactic acid bacteria
and yeast forms antibiotic substances.
The next step was the selection leaven
from yeast strains and lactic acid
bacteria and to create kumis starter.
Microbial associations which contain Lactic
acid bacteria and yeast are the principal organisms involved in the manufacture
of a lot of dairy products. In some fermented dairy products, additional
bacteria, referred to as secondary microflora, are added to produce carbon
dioxide, which influences the flavor and alters the texture of the final
product.
A total of 10 tested combinations of lactic streptococci and sticks.
Strains Str. lactis in a monoculture inferior to acid production strains of
Lactobacillus acidophilus, however, in a joint grow with the Str. lactis
acidity activity greatly improved. Also, it is known that yeast play an
important role in the preparation koumiss so further work to choose yeast together with lactic acid bacteria. We tested 8 different strains
of yeast Torulopsis sphaerica, Torulopsis kefir var. kumis and Candida
mycoderma, isolated from kumis, fermented mare's milk. Then in combination with
lactic acid bacteria Lb. acidophilus, Str. lactis, selected from previous
experiments we prepared leaven strains. When culture is cultivated we take attention to the energy acid
formation, the growth rate of yeast and lactic acid bacteria. Kumis leaven prepared from the sterile milk. Cultures of
lactic acid bacteria Lb. acidophilus, Str. lactis and yeast Torulopsis
sphaerica grown separately and mixed in a ratio of 1: 1: 0.5 immediately before
fermentation kumis.
The
results were tested in the course of fermentation hourly, in terms of taste. Mare's milk with starter cultures has a sour taste odor, it gives the beverage a smoother texture and better flavor.
In addition, we also determined the antagonistic activity kumis starters , the
optimal composition of combinations of kumis fermentation. The results of these
experiments are shown in Table 2. The results of the research in this field
argue that the finished product obtained by the new method shows high
antagonistic activity against the saprophytic and pathogenic bacteria (an
inhibition of 12-28 mm).
Table 2 - Influence of the different combinations
lactic acid bacteria and yeast on quality of the kumis
|
¹ |
Organoleptic
factors |
|
|
1 |
Kumis pleasing, sour milk
taste, fermented, little carbonated |
|
|
2 |
Kumis pleasing, refreshing,
carbonated, homogeneous, fermented, |
|
|
3 |
Kumis little carbonated, water taste |
|
|
4 |
Kumis pleasing, sour milk
taste, fermented, powerfully carbonated |
|
|
5 |
Kumis sour milk taste,
little carbonated, homogeneous, |
|
|
6 |
Kumis sour milk taste, little
carbonated, pleasing, homogeneous, |
|
|
7 |
Kumis sour milk taste,
weakly, fermented, homogeneous, |
|
|
8 |
Kumis fermented, carbonated, pleasing |
|
|
9 |
Kumis sour milk taste, carbonated, pleasing |
|
|
10 |
Kumis sour milk taste,
fermented, little carbonated |
Thereby among of all tested yeasts the best starter kumis were Lb. acidophilus, + Str.
lactis, + T. sphaerica ¹2. We
investigated the effect of the leaven to intensity of the fermenting mare's
milk, the quality kumis, acid-and aromatic formation in kumis. The results of
the experiment are also re- confirmed the high quality of this product.
List
of references