JDS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

J. Dairy Sci. 2007. 90:5361-5373. doi:10.3168/jds.2007-0273
© 2007 American Dairy Science Association ®
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Interpretive Summary
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Grattepanche, F.
Right arrow Articles by Lacroix, C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Grattepanche, F.
Right arrow Articles by Lacroix, C.

Enhancement of Functional Characteristics of Mixed Lactic Culture Producing Nisin Z and Exopolysaccharides During Continuous Prefermentation of Milk with Immobilized Cells

F. Grattepanche*, P. Audet{dagger} and C. Lacroix{ddagger}

* STELA Dairy Research Center, Pavillon Paul-Comtois, Université Laval, Québec, Québec, G1K 7P4 Canada
{dagger} École des sciences des aliments, de nutrition et d’études familiales, Pavillon Jacqueline-Bouchard, Université de Moncton, Moncton, New Brunswick, E1A 3E9 Canada
{ddagger} Laboratory of Food Biotechnology, Institute of Food Science and Nutrition, Swiss Federal Institute of Technology, ETH-Zürich, Schmelzbergstrasse 7, 8092 Zürich, Switzerland

1 Corresponding author: christophe.lacroix{at}ilw.agrl.ethz.ch

Antagonistic phenomena between strains often occur in mixed cultures containing a bacteriocinogenic strain. A nisin Z producer (Lactococcus lactis ssp. lactis biovar. diacetylactis UL719) and 2 nisin-sensitive strains for acidification (Lactococcus lactis ssp. cremoris ATCC19257) and exopolysaccharide (EPS) production (Lactobacillus rhamnosus RW-9595M) were immobilized separately in gel beads and used to continuously preferment milk at different temperatures, with pH controlled at 6.0 by fresh milk addition. The process showed high volumetric productivity, with an increase from 8.0 to 12.5 L of prefermented milk per liter of reactor volume and hour as the temperature was increased from 27 to 35°C. Lactococcus lactis ssp. lactis biovar. diacetylactis UL719 counts in prefermented and fermented (22-h batch fermentation) milks were stable during 3 wk of continuous fermentation (8.1 ± 0.1 and 8.9 ± 0.2 log cfu/mL, respectively). The L. lactis ssp. cremoris population (estimated with real-time quantitative PCR) decreased rapidly during the first week of continuous culture to approximately 4.5 log cfu/mL and remained constant afterward. Lactobacillus rhamnosus counts in prefermented and fermented milks significantly increased with prefermentation time, with no temperature effect. Nisin Z reached high titers in fermented milks (from 177 to 363 IU/mL), with EPS concentration in the range from 43 to 178 mg/L. Immobilization and continuous culture led to important physiological changes, with Lb. rhamnosus becoming much more tolerant to nisin Z, and Lb. rhamnosus and L. lactis ssp. lactis biovar. diacetylactis UL719 exhibiting large increases in milk acidification capacity. Our data showed that continuous milk prefermentation with immobilized cells can stimulate the acidification activity of low-acidifying strains and produce fermented milks with improved and controlled functional properties.

Key Words: immobilization • exopolysaccharide mixed culture • continuous fermentation






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2007 by the American Dairy Science Association ®.