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

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

Simposio; 12th Symposium on Lactic Acid Bacteria; 2017

Lactic acidbacteria (LAB) are commonly used as starter cultures in food fermentations.Autochthonous LAB are preferable to allochthonous strains as they possessniche-specific properties, which are essential to develop successful food andbeverage fermentations. In this work, we aimed to evaluate relevant functionalproperties of LAB (Lactococcus lactis FMy2-21-2 and FN3-317, and Lactobacillusrhamnosus H3F-210) isolated from tropical fruits and fruit flowers. Esteraseand cinnamoyl activities, ethyl-ester synthesis, and growth and acidificationcapacities of the strains were determined. The esterase specific activity(ESA), playing a key role in flavor development, was measuredspectrophotometrically using α-naphthyl (α-NA) derivatives (C2, C3, C4, C8, C10and 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 byesterification using butanoic acid or hexanoic acid plus ethanol was assayed andthe formed esters were determined by GC. Lc. lactis FN3-317 was able to produceEtC2, 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: 35.9nmol/mg prot). Cinnamoyl esterases hydrolyze hydroxycinnamates normally presentin fruits releasing the corresponding hydroxycinnamic acid with antioxidantproperties. Only the lactococci strains showed cinnamoyl esterase activitybreaking down ethyl ferulate, which was used as substrate. The Lactococcusstrains showed rapid acidification ability at 8 h incubation (ΔpH: 1.69-1.71)while the most acidifying LAB after 24 h was L. rhamnosus (ΔpH: 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 usedas potential starter cultures for fermented fruit-based products.