Safety Assessment and Preliminary In Vitro Evaluation of Probiotic Potential of Lactococcus lactis Strains Naturally Pre
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Safety Assessment and Preliminary In Vitro Evaluation of Probiotic Potential of Lactococcus lactis Strains Naturally Present in Raw and Fermented Milk Kristina Kondrotiene1 · Lina Lauciene1 · Vaida Andruleviciute2 · Neringa Kasetiene1 · Loreta Serniene1 · Dalia Sekmokiene1 · Mindaugas Malakauskas1 Received: 31 January 2020 / Accepted: 7 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The present study was conducted to find the potential of Lactococcus lactis strains naturally present in raw and fermented milk as probiotics and to evaluate their safety and some technological characteristics. There are numerous studies that evaluated probiotic properties of lactococci, nevertheless, limited studies on the probiotic potential of lactococci isolated from raw milk or dairy products were performed. Strains isolation from raw milk or dairy products and their characterization is important when selection of starter strains for the production of functional dairy foods is performed. Depending on aroma production and acidifying activity, 33 L. lactis strains were selected out of 169 and evaluated for safety, technological and probiotic properties. These strains were screened for antibiotic sensitivity, enzymatic activity, hemolytic and gelatinase activities. The strains were also assessed for resistance to bile salts and acid, growth in bile acids and cholesterol, cell surface hydrophobicity. Based on the obtained results, two strains with the best probiotic potential were selected. These two L. lactis strains, with 51% and 67% survival at low pH and more than 80% resistance to various bile salt concentrations, proved their resistance in vitro to gastric conditions. Also these strains proved to be good acidifiers (the pH of milk was reduced by at least 1 unit in 6 h at 30–37 °C) and can be used in the development of functional dairy foods as starter cultures.
Introduction In recent years, due to the growing interest in food products that has added health benefits, food is used not only to provide the necessary nutrients, but also to provide health-promotion effects to consumers’ health [1, 2]. This raised probiotic food products consumption [3]. Probiotics are defined as non-pathogenic microorganisms which, when administered in sufficient numbers, provide a health benefit to the host [4, 5]. The most common microorganisms applied as probiotics are lactic acid bacteria (LAB)-industrially important microorganisms worldwide for the fermented food production [6]. For a long time dairy products like raw milk served as a * Kristina Kondrotiene [email protected] 1
Department of Food Safety and Quality, Veterinary Academy, Lithuanian University of Health Sciences, Tilzes st. 18, 47181 Kaunas, Lithuania
Department of Biochemistry, Veterinary Academy, Lithuanian University of Health Sciences, Tilzes st. 18, 47181 Kaunas, Lithuania
2
major ecological reservoir for isolation of various beneficial microorganisms, because raw milk contains wide microbial diversity, composed
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