SELENIUM BIOENRICHMENT OF A MANGO-PASSION FRUIT JUICE THROUGH LACTIC ACID BACTERIA FERMENTATION

LAURA CRESPO; OMAR F. ORDOÑEZ; RAIMONDO GAGLIO; LUCA SETTANNI; FERNANDA MOZZI; MICAELA PESCUMA

Congreso; XV CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL SAMIGE; 2020

Fruits are a unique source of fibers, vitaminsand other bioactive compounds necessary in human diet. Selenium (Se) is anessential micronutrient and its deficiency is related to the development ofcardiovascular diseases, cancer, diabetes, thyroiddisorders and male infertility. In Argentina, Se intakes are below therecommended daily ingest (30 µg). Soluble inorganic Se forms such as seleniteand selenate are toxic. Some lactic acid bacteria (LAB) are capable ofbio-transforming Se into Se-amino acids and Se-nanoparticles. The aim was toevaluate the capacity Levilactobacillusbrevis CRL 2051 and Fructobacillus tropaeoliCRL 2034 to grow and bio-accumulate Se in a mango-passion fruit mixed juice. L. brevis CRL 2051 and F. tropaeoli CRL 2034 were grown aloneor in mixed cultures (30 °C, 24 h) in non-pasteurized  or pasteurized fruit juices with or withoutSe (0.15 mg /L of Na2SeO3). L. brevis CRL 2051 and F. tropaeoli CRL 2034 grew under all theconditions assayed (1.0 and 2.0 log cfu/ml) and were not affected by thepresence of Se. In non-pasteurized samples, fungi (0.0-1.2 and 0.0-3.8 logcfu/ml, at 0 and 24 h, respectively) and yeasts (0.0-2.2 and 0.0-5.7 log cfu/mlat time 0 and 24 h, respectively) were detected, being the cell counts higherfor the control samples and lower for those inoculated with F. tropaeoli CRL 2034. Moreover, innon-inoculated and non-pasteurized MRS plates bacteria consistent with LAB wereobserved, while Enterobacteriawere not detected in any of the assayed samples. RAPD?PCR analysis were done withcolonies found in MRS plates from non-pasteurized samples showed that L. brevis CRL 2051 and F. tropaeoli CRL 2034 were present alongthe fermentation process; however, they were not able to eliminate the nativefruit microbiota. In inoculated samples, pH decreased between 0.21 and 0.64 U. Sucrose(11.9 g/L), glucose (4.5 g/L), and fructose (4.3 g/L) were the carbohydrates foundin the mango-passion fruit juices by RP-HPLC. F. tropaeoli CRL 2034 consumedmore glucose (5.7 g/L) and fructose (4.1 g/L) than L. brevis CRL 2051 (3.8 and 5.5 g/L, glucose and 1.9-2.6 g/L,fructose, without or with Se, respectively); the latter strain produced onlylactic acid (2.2 and 3.6 g/L, without and with Se, respectively) while F. tropaeoli CRL 2034 produced lactic(1.1 and 1.3 g/L) and acetic acid (0.8-0.9 g/L) in both Se and control samples.Mannitol concentration was higher in the absence of Se (37.3%). The highest Seconcentration (70 µg/L) was detected (ICP-MS) in cells of the mixed culturefermented beverage. In general, the polyphenol content (Folin- Ciocalteu) washigher in the Se-containing beverages, which increased after fermentation with F. tropaeoli CRL 2034 (73%) and with themixed culture (20%). Thus, fermentation of mango-passion fruit juices with F. tropaeoli CRL 2034 or with the mixedculture could be an interesting strategy for formulating Se-enriched functionalfoods.