Selenium Bioenrichment of a Mango ?Passion fruit juice through lactic acid bacteria fermentation.

CRESPO, L.; ORDOÑEZ, O.; GAGLIO, RAIMONDO; SETTANNI, LUCA; MOZZI, F.; PESCUMA, M.

Congreso; SAIB-SAMIGE 2020; 2020

Fruits are a unique source of fibers, vitamins and other bioactive compounds necessary in human diet. Selenium (Se) is an essential micronutrient and its deficiency is related to the development of cardiovascular diseases, cancer, diabetes, thyroid disorders and male infertility. In Argentina, Se intakes are below the recommended daily ingest (30 µg). Soluble inorganic Se forms such as selenite and selenate are toxic. Some lactic acid bacteria (LAB) are capable of bio-transforming Se into Se-amino acids and Se-nanoparticles. The aim was to evaluate the capacity Levilactobacillus brevis CRL 2051 and Fructobacillus tropaeoli CRL 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 alone or in mixed cultures (30 °C, 24 h) in non-pasteurized or pasteurized fruit juices with or without Se (0.15 mg /L of Na2SeO3). L. brevis CRL 2051 and F. tropaeoli CRL 2034 grew under all the conditions assayed (1.0 and 2.0 log cfu/ml) and were not affected by the presence of Se. In non-pasteurized samples, fungi (0.0-1.2 and 0.0-3.8 log cfu/ml, at 0 and 24 h, respectively) and yeasts (0.0-2.2 and 0.0-5.7 log cfu/ml at time 0 and 24 h, respectively) were detected, being the cell counts higher for the control samples and lower for those inoculated with F. tropaeoli CRL 2034. Moreover, in non-inoculated and non-pasteurized MRS plates bacteria consistent with LAB were observed, while Enterobacteria were not detected in any of the assayed samples. RAPD?PCR analysis were done with colonies found in MRS plates from non-pasteurized samples showed that L. brevis CRL 2051 and F. tropaeoli CRL 2034 were present along the fermentation process; however, they were not able to eliminate the native fruit 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 found in the mango-passion fruit juices by RP-HPLC. F. tropaeoli CRL 2034 consumed more 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 only lactic 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 Se concentration (70 µg/L) was detected (ICP-MS) in cells of the mixed culture fermented beverage. In general, the polyphenol content (Folin- Ciocalteu) was higher in the Se-containing beverages, which increased after fermentation with F. tropaeoli CRL 2034 (73%) and with the mixed culture (20%). Thus, fermentation of mango-passion fruit juices with F. tropaeoli CRL 2034 or with the mixed culture could be an interesting strategy for formulating Se-enriched functional foods.