SELECTION OF POTENTIAL PROBIOTIC LACTIC ACID BACTERIA ISOLATED FROM Opuntia ficus-indica FRUITS TO OBTAIN A FERMENTED JUICE WITH FUNCTIONAL PROPERTIES

TORRES, DI RISIO, ISLA

Tucuman

Simposio; IV International Symposium on Lactic Acid Bacteria: Food, Health and Applications; 2013

CERELA

Cactus fruits (Opuntia ficus‐indica) have attracted great interest because of their nutritional and health improving properties. Scientific evidence has provided about the benefits from fruit ingestion with special consideration about potentially active antioxidant phytochemicals. In many places cactaceae fruits are consumed as juice. Unfortunately, its low acidity combined to high soluble solids content makes this fruit susceptible to microbial attack limiting its storage life. Different procedures were developed to prevent spoilage. However, the final products do not resemble to original fresh juice due to changes in colour and flavour. The aim of this study was to isolate and select probiotic candidate strains for the preparation of a probiotic beverage from O. ficus‐indica fruit juice in order to preserve or improve its functional and sensorial properties. Mature fruits were collected in the north‐west of Tucuman (Colalao del Valle, Tucuman, Argentina). Lactic acid bacteria (LAB) were isolated from them, and also from commercial cow milk previously enriched in sterile juice. Isolation of mesophilic LAB was made on MRS agar at 37 °C for 48‐72 h under anaerobiosis. Isolated strains were screened for probiotic traits such as acid and bile tolerance, acidification of culture medium and hydrophobicity, and also for their ability to growth in pasteurized juice (64 °C, 30 min). The microbial viability, pH, pigments content (betanin and indicaxanthin) as well as the antioxidant activity (ABTS free radical scavenging activity) were evaluated in fermented juices. 19 strains were isolated on MRS plates at 37 °C; 17 of them from cactus pear and 2 from milk. These isolates were Gram‐positive, catalase‐negative, non‐motile, homofermentative and aerotolerant rods and coccobacilli, able to grow between 15 and 42 °C and were able to acidify MRS broth. Most isolates were resistant to pH 3 and all of them showed great resistance to bile salts (2 g/100 ml). The majority of the isolated strains showed low hydrophobicity values (