Survival of Weissella confusa and Lactobacillus paracasei strains in fermented milks under cold storage and after freeze-drying

The technological properties of two Lactobacillus paracasei (UI014 and UI022) and two Weissella confusa (UI006 and UI007) strains were studied in order to ascertain their suitability to be used in the formulation of probiotic fermented milks. All strains were able to grow in milk increasing their counts for more than 2 logarithmic units. Additionally, L. paracasei strains were able to acidify and coagulate the milk which indicates that they can be employed as starter cultures. However, W. confusa strains can only be used as adjunct cultures since their acidification rate was very low. The viability of most strains declined slowly during the cold storage of the dairy product and after 4 weeks, their counts remained approximately 107 cfu/ml. Thus, the shelf life of these dairy products is long enough to ensure the intake of viable cells that could promote health benefits. Finally, the four strains studied presented high survival after the freeze-drying process using skim milk as cryo-protectant. Thus this technology can be employed to supply these strains to the dairy industries to be used as starter or adjunct cultures for the formulation of probiotic foods.This work was financed by FEDER funds (European Union) and the Spanish Plan Nacional de I+D+i through the project AGL2006-03336 and AGL2007-62736.Peer Reviewe

Überleben von Weissella confusa- und Lactobacillus paracasei-Stämmen in fermentierten Milchen unter Kühllagerung und nach der Gefriertrocknung

The technological properties of two Lactobacillus paracasei (UI014 and UI022) and two Weissella confusa (UI006 and UI007) strains were studied in order to ascertain their suitability to be used in the formulation of probiotic fermented milks. All strains were able to grow in milk increasing their counts for more than 2 logarithmic units. Additionally, L. paracasei strains were able to acidify and coagulate the milk which indicates that they can be employed as starter cultures. However, W. confusa strains can only be used as adjunct cultures since their acidification rate was very low. The viability of most strains declined slowly during the cold storage of the dairy product and after 4 weeks, their counts remained approximately 107 cfu/ml. Thus, the shelf life of these dairy products is long enough to ensure the intake of viable cells that could promote health benefits. Finally, the four strains studied presented high survival after the freeze-drying process using skim milk as cryo-protectant. Thus this technology can be employed to supply these strains to the dairy industries to be used as starter or adjunct cultures for the formulation of probiotic foods.Die technologischen Eigenschaften von zwei Lactobacillus paracasei- (UI014 und UI022) und zwei Weissella confusa- (UI006 und UI007) Stämmen wurden mit der Zielsetzung untersucht, ihre Brauchbarkeit für die Herstellung probiotischer fermentierter Milchen zu ermitteln. Alle Stämme waren in der Lage, sich in Milch zu vermehren (Erhöhung der Keimzahlen um mehr als zwei Zehnerpotenzen). Zusätzlich säuerten und koagulierten die L. paracasei-Stämme die Milch, was darauf hinweist, dass sie als Säurewecker geeignet sind. Im Gegensatz hierzu können W. confusa-Stämme lediglich als Zusatzkulturen eingesetzt werden, da ihre Säuerungsraten sehr niedrig liegen. Die Lebensfähigkeit der meisten Stämme nahm langsam während der Kühllagerung der Produkte ab, und nach vier Wochen blieben die Keimzahlen bei etwa 107 KbE/ml. Die Haltbarkeit dieser Milchprodukte ist somit lang genug, um die Aufnahme lebensfähiger Zellen mit möglicherweise gesundheitlichen Vorteilen zu ermöglichen. Die vier untersuchten Stämme zeigten hohe Überlebensraten nach dem Gefriertrocknungsprozess, wobei Magermilch als „Gefrierschutz" diente. Somit kann dieser Technologie zur Versorgung der Milchwirtschaft mit Säurewecker- oder Zusatzkulturen bei der Herstellung probiotischer Lebensmittel empfohlen werden.Fil: Ayeni, Funmilola A.. University of Ibadan; NigeriaFil: Adeniyi, Bolanle A.. University of Ibadan; NigeriaFil: Ogunbanwo, Samuel T.. University of Ibadan; NigeriaFil: Nader, Maria Elena Fatima. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Ruas Madiedo, Patricia. Consejo Superior de Investigaciones Científicas; España. Consejo Superior de Investigaciones Científicas. Instituto Superior de Productos Lácteos de Asturias; Españ