African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12291

Full Length Research Paper

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.
Email: [email protected]

  •  Accepted: 27 November 2009
  •  Published: 08 March 2010

Abstract

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-NH2released 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.