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Growth, acidification and proteolysis performance of two
co-cultures (Lactobacillus plantarum-Bifidobacterium longum
and Streptococcus thermophilus-Bifidobacterium longum)
K. Belkaaloul1, A. Chekroun1, A.
Ait-Abdessalam2, D. Saidi1 and Kheroua
O.1*
1Laboratory
of Physiology of Nutrition and Food Safety, Department of
Biology, Faculty of science, University of Oran, Es-Senia
Oran-31000, Algeria.
2Laboratory
of Food and Industrial Microbiology, Department of Biology,
Faculty of science, University of Oran, Es-Senia Oran-31000,
Algeria.
*Corresponding author. E-mail:
omar_kheroua@hotmail.com. Tel/Fax: +213 41 513025.
Accepted 27 November, 2009 |
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In this
study, the fermentation and proteolysis of two co-cultures
were investigated. Two fermented cow skim-milk lactoferrin 1
(LF1) and lactoferrin 2 (LF2) were prepared. LF1 was
inoculated with Bifidobacterium longum (Bf I) and
Streptococcus thermophillus (St I) while LF2 was inoculated
with Lactobacillus plantarum (Lb O) and B. longum (Bf I).
Incubation was at 42°C for 8 h. The enumeration revealed
bacterial growth in all fermented milk. Maximum growth of
(Lb O) and (Bf I) was observed when mixed together after 2 h
of fermentation in comparison with Bf I and St I with values
of 109 and 3.108 cfu/ml, respectively.
The kinetics of acidification (pH and lactic acid
production) gave significant values (p < 0.01) for LF2 when
compared to LF1 and sterile milk (LS). The proteolytic
activity (functions
α-NH2
released in
μM/mg)
and total proteins (in µg/mg) gave significant values (p <
0.05) for LF2 when compared to LF1. Two mixed cultures (Lb
O- Bf I) and (St I-Bf I) showed proteolysis of ß-lactoglobulin
(ß-Lg) and α-lactalbumin (α-la).
Key
words:
Bifidobacteria longum, Lactobacillus plantarum,
Streptococcus thermophillus, cow milk, fermented milk,
milk’s proteins, proteolysis. |
