PRODUCTION OF FERMENTED MILK BY BIFIDOBACTERIA STRAINS ABLE TO PRODUCE CONJUGATED FATTY ACIDS

V. TERÁN; P. LUNA PIZARRO ; R. MEDINA; C. VAN NIEUWENHOVE

San Miguel de Tucumán

Simposio; V International Symposium on Lactic Acid Bacteria; 2016

CERELA-CONICET

Bifidobacteria are commonly usedin fermented milk production due to their well-documented health promoting propertieson human health. However, the inclusion of these microorganisms is a great challenge in dairy industrydue to their nutritional requirements and low tolerance to stress. The aim of this work was to elaborate fermentedmilks with bifidobacteria strains, previously selected by its conjugated fattyacid production. Therefore, conventional semi-skimmed milks were tempered at 37°Cand inoculated at 2% with two  bifidobacteria strains (B. animalis subsp. lactisINL2 and B. breve ZL1228) and onelactobacilli strain (L. paracaseisubsp. paracasei CRL 731), selectedfor its aroma production. Jacaranda (JO) or sunflower (SO) oil were added at500 µg mL-1 as sources of bioactive lipids and to serve as substratesfor further conversion to conjugated fatty acids. Fermentations were stopped atpH 4.4 by rapid cooling and stored for 21 days at 4°C. Samples were taken toevaluate bacterial counts, pH and fatty acid profile during time. Results showed that bifidobacteria strains wereable to produce conjugated linoleic (CLA) and linolenic (CLNA) acids duringmilk fermentation under aerobic conditions (from 5.6 to 10.4%). Changes onfatty acids profiles were observed. Likewise, saturated fatty acids (SFA) contentdecreased during fermentation, except in fermented milk with JO. Monounsaturatedfatty acid content (MUFA) increased during fermentation and decreased duringstorage, except in fermented milk with JO. Polyunsaturated fatty acids (PUFA) contentwas higher when JO was added to milk, being linoleic acid (C18:2) the mostprevalent one. PUFA content also decreased after 21 days of cold storage. Bifidobacteriagrew appreciably after 24 h of fermentation (approx. 1.0 x 10 8 cfu mL-1) beinghigher in presence of JO (2.6 x 10 8 cfu mL-1). After 21days of cold storage, cell counts in different milks increased to 1.0 x 10 9cfu mL-1. Cultivability of CRL 731 strain after fermentationvaried from 5.8 x 10 8 to 1.1 x 10 9 cfu mL-1,remaining stable all along storage period. Data obtained in this study allowedpointing out relationships between survival of bifidobacteria and fatty acidcomposition in fermented milks, demonstrating that these microorganisms wereable to growth and maintain viable in presence of oxygen and during coldstorage. These results and the higher CLA and CLNA content in milks fermentedwith bifidobacteria allow the manufacture of fermented milks enriched withbioactive lipids which show beneficial health properties for humans.