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

L. CRESPO; O.F ORDOÑEZ; F. MOZZI; M. PESCUMA

VIRTUAL

Congreso; Reunion conjunta 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 the Se intakes is below the recommended daily ingest (30µg).The soluble inorganic Se forms such as selenite and selenite 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 unpasteurized or pasteurized fruit juices with or without Se (0.15 mg /L of Na2SeO3). L. brevis CRL 2051 and F. tropaeoli CRL 2034 grew in all the conditions assayed (1.0 and 2. log cfu/ml) and were not affected by the presence of Se. In the unpasteurized samples, fungi (0.0-1.2 and 0.0-3.8log 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 observed, being the cell counts higher for the control samples and lower for those inoculated with F. tropaeoli CRL 2034. Moreover, in the non-inoculated and non-pasteurized MRS plates bacteria consistent with LAB were observed, while Enterobacteriaceae were not detected in any of the assayed samples. The RAPD–PCR analysis done for the colonies found in MRS plates of the 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 the inoculated samples pH decreased between 0.21 and 0.64. The carbohydrates present in the mango/passion fruit juices detected by RP-HPLC were sucrose (11.9 g/L) glucose (4.5 g/L) and fructose (4.3 g/L). 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, while a higher mannitol concentration was observed in the absence of Se (37.3%). The highest Se concentration (70 µg/L) was detected (ICP-MS) in the pellet of the mixed culture fermented beverage. In general the polyphenol content (Folin- Ciocalteu) was higher in the beverages containing Se and its concentration increased after fermentation with F. tropaeoli CRL 2034 (73%) and the mixed culture (20%). Fermentation of mango/passion fruit juices with F. tropaeoli CRL 2034 or the mixed culture could be an interesting strategy for formulating functional foods enriched with Se.