Functional properties of lactic acid bacteria isolated from tropical fruits and fruit flowers

L RUIZ RODRIGUEZ; L DE VUYST; E M HEBERT; F MOZZI; M F MOHAMED; R MEDINA

Egmond and Zee

Simposio; 12th International Symposium on Lactic Acid Bacteria; 2017

Royal Netherlands Society for Microbiology (KNVM), Federation of European Microbiological Societies(FEMS)

Lactic acid bacteria (LAB) are commonly used as starter cultures in food fermentations. Autochthonous LAB are preferable to allochthonous strains as they possess niche-specific properties, which are essential to develop successful food and beverage fermentations. In this work, we aimed to evaluate relevant functional properties of LAB (Lactococcus lactis FMy2-21-2 and FN3-317, and Lactobacillus rhamnosus H3F-210) isolated from tropical fruits and fruit flowers. Esterase and cinnamoyl activities, ethyl-ester synthesis, and growth and acidification capacities of the strains were determined. The esterase specific activity (ESA), playing a key role in flavor development, was measured spectrophotometrically using α-naphthyl (α-NA) derivatives (C2, C3, C4, C8, C10 and C12 carbon atoms) as substrates. All strains showed ESA with α-NA-C2, C3, C4 and C8 derivatives; none of them were active against α-NA-C12 while only L. rhamnosus hydrolyzed α-NA-C10. Ethyl ester-synthesizing activity by esterification using butanoic acid or hexanoic acid plus ethanol was assayed and the formed esters were determined by GC. Lc. lactis FN3-317 was able to produce EtC2, EtC3, and EtC4, Lc. lactis FMy2-21-2 synthesized EtC2 and EtC3, and L. rhamnosus EtC2 and EtC4 (the amount of EtC4 being the highest produced: 35.9 nmol/mg prot). Cinnamoyl esterases hydrolyze hydroxycinnamates normally present in fruits releasing the corresponding hydroxycinnamic acid with antioxidant properties. Only the lactococci strains showed cinnamoyl esterase activity breaking down ethyl ferulate, which was used as substrate. The Lactococcus strains showed rapid acidification ability at 8 h incubation (pH: 1.69-1.71) while the most acidifying LAB after 24 h was L. rhamnosus (pH: 2.44). Finally, the three strains were able to grow and survive in tropical fruit juice at 30 °C for 24 h. The studied LAB exhibit desirable functional properties to be used as potential starter cultures for fermented fruit-based products.