Formulation of a selenized fermented drink with strains of Lactobacillus brevis and Fructobacillus tropaeoli

FERNANDA BEATRIZ MOZZI; EMILIA CUENCAS BARRIENTOS; MICAELA PESCUMA; FERNANDO GABRIEL MARTÍNEZ

Córdoba

Congreso; VII Congreso Internacional de Ciencia y Tecnología de los Alimentos; 2018

Formulation of a selenized fermented drink with strains of Lactobacillus brevis and Fructobacillus tropaeoli Cuencas Barrientos E (1), Martínez F G (1), Mozzi F (1), Pescuma M (1)(1) Centro de Referencia para Lactobacilos (CERELA-CONICET), Chacabuco 145, San Miguel de Tucumán, Argentina.fmartinez@cerela.org.arSelenium (Se), which is present as SeCys in seleno-proteins, is involved in cancer prevention, thyroid functioning, and pathogen inhibition. Se is incorporated in the diet through Se-containing foods. Lactic acid bacteria (LAB) are commonly used in the food industry due to their capacity to increase food safety and stability. Moreover, some LAB may biotransform inorganic Se (toxic) into organic forms such as Se-amino acids and Se-nanoparticles (SeNPs). We aimed to formulate a fermented milk/fruit juice beverage using strains that biotransform and accumulate Se intracellularly. Lactobacillus brevis 73 and Fructobacillus tropaeoli 108 were grown in MRS with or without selenite (5 mg/L), cells were washed and used for inoculating a milk/mango-orange fruit mixture (4:1, v/v) at 30 °C for 14 h. Microbial growth (cfu/ml), sugar, organic acids and ethanol concentrations (HPLC) and protein degradation (SDS-PAGE) were determined at the end of fermentation. Selenium content in the drink was determined by atomic abortion, while the presence of SeNPs was analyzed by scanning electronic microscopy (SEM). The survival of the strains under storage conditions (4°C, 28 days) and after digestion (using an in vitro digestive system) was also determined. Selenized and non-selenized cells grew well (between 9.2 and 9.8 cfu/ml at 14 h) and acidified the matrix (̴ 0.8 U) at a similar extent. L. brevis 73 fermented glucose (2.6-1.9 g/L, control and selenized cells, respectively) in a higher extent than fructose (0.7-0.9) and produced lactic acid (2.0-1.7 g/L). Both control and selenized cells of F. tropaeoli 108 consumed mainly fructose (4.2-4.5 g/L) and produced mannitol (4.6-4.7 g/L) while glucose was consumed in a lesser extent releasing lactic and acetic acid (1.5-1.1 and 1.0 g/L, respectively). The studied strains could not degrade the proteins present in the milk/fruit mixture. SEM imagines of the fermented drinks revealed the presence of SeNPs attached to the cell surface of the selenized L. brevis and F. tropaeoli strains; however, Se was detected only in the supernatant of the L. brevis selenized fermented drink at a concentration of 100 µg/L. Under storage conditions, a decrease of 1 log U cfu/ml was observed for the selenized L. brevis strain after 28 days incubation while no effect on cell viability was observed for the non-selenized strain. Inversely, a decrease in the cell counts (0.7 U log cfu/ml) of control and selenized cells of F. tropaeoli 108 was observed after 14 days at 4°C. L. brevis 73 was able to survive to the in vitro gastrointestinal tract while a drastic decrease (2.6-0.8 U log cfu/ml) in F. tropaeoli 108 cell count was observed; the selenized cells being more resistant than the control ones. These strains could be used in the production of novel Se-bioenriched fermented drinks.Key words: Lactic acid bacteria, Selenium, fermented drinks