EFFETS DES FIBRES DE CAROUBE SUR LE DEVELOPPEMENT ET LA SURVIE POSTFERMENTAIRE DES SOUCHES BENEFIQUES SUR MILIEU LAIT ECREME

Abstract

The aim of the present study is to explore the effects of Ceratonia siliqua (L.) carob pod fibers, extracted by an hydro-thermal method, on kinetic of growth and acidification; and also on survival and post-acidifying activity of yogurt starters (Streptococcus thermophilus and Lactobacillus delbrueckii ssp bulgaricus) in mixed culture with Lactobacillus rhamnosus LBRE-LSAS or Bifidobacterium animalis subsp. lactis in a 10% (w/v) reconstituted and fermented skimmed milk during four weeks of a refrigerated storage. The obtained results have shown that carob fibers enhance growth of Lactobacillus rhamnosus LBRE-LSAS (+11.94%), Bifidobacterium animalis subsp lactis (+7.98%), Streptococcus thermophilus (10.93%) and Lactobacillus delbrueckii ssp bulgaricus (24.66%). In spite of the acidity of the added fiber extract (pH 5.2), the Curdling time of milk was slightly prolonged by 10 to 20 minutes according to the involved strains in fermentation process. The best survival scores registered after 4 weeks of refrigerated storage of yogurts containing carob fibers, were those of the starters; whereas a dramatic decrease in that of beneficial bacteria, except during the two first weeks of storage, was observed. Higher pH values were registered in the presence of carob fibers in yogurts containing Lactobacillus rhmnosus LBRE-LSAS (3.72 to 4.15) or Bifidobacterium animalis subsp lactis Bb12 (3.66 to 4.00); comparatively to those of the control ((3.54 et 3.38).