Effect of buckwheat flour and oat bran on growth and cell viability of the probiotic strains Lactobacillus rhamnosus IMC 501 ® , Lactobacillus paracasei IMC 502 ® and their combination SYNBIO ® , in synbiotic fermented milk Maria Magdalena Coman a,b, ⁎, Maria Cristina Verdenelli b,c , Cinzia Cecchini b,c , Stefania Silvi b,c , Aida Vasile d , Gabriela Elena Bahrim d , Carla Orpianesi c , Alberto Cresci b,c a School of Advanced Studies, University of Camerino, Camerino, Italy b School of Biosciences and Biotechnologies, University of Camerino, Camerino, Italy c Synbiotec S.r.l., Spin-off of UNICAM, Camerino, Italy d Faculty of Food Science and Engineering, “Dunarea de Jos” University, Galati, Romania abstract article info Article history: Received 27 March 2013 Received in revised form 6 August 2013 Accepted 24 September 2013 Available online 2 October 2013 Keywords: Probiotics Lactobacillus Prebiotics Synbiotic Buckwheat flour Oat bran Fermented foods have a great significance since they provide and preserve large quantities of nutritious foods in a wide diversity of flavors, aromas and texture, which enrich the human diet. Originally fermented milks were developed as a means of preserving nutrients and are the most representatives of the category. The first aim of this study was to screen the effect of buckwheat flour and oat bran as prebiotics on the production of probiotic fiber-enriched fermented milks, by investigating the kinetics of acidification of buckwheat flour- and oat bran- supplemented milk fermented by Lactobacillus rhamnosus IMC 501 ® , Lactobacillus paracasei IMC 502 ® and their 1:1 combination named SYNBIO ® . The probiotic strains viability, pH and sensory characteristics of the fermented fiber-enriched milk products, stored at 4 °C for 28 days were also monitored. The results showed that supplementation of whole milk with the tested probiotic strains and the two vegetable substrates results in a significant faster lowering of the pH. Also, the stability of L. rhamnosus IMC 501 ® , L. paracasei IMC 502 ® and SYNBIO ® during storage at 4 °C for 28 days in buckwheat flour- and oat bran-supplemented samples was remarkably enhanced. The second aim of the study was to develop a new synbiotic product using the best combination of probiotics and prebiotics by promoting better growth and survival and be acceptable to the consumers with high concentration of probiotic strain. This new product was used to conduct a human feeding trial to validate the fermented milk as a carrier for transporting bacterial cells into the human gastrointestinal tract. The probiotic strains were recovered from fecal samples in 40 out of 40 vol- unteers fed for 4 weeks one portion per day of synbiotic fermented milk carrying about 10 9 viable cells. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Humans have been consuming probiotics in the form of fermented foods for many years (Ranadheera et al., 2010) and the health benefits of probiotics have been known for a long time. After discovering the im- portance of viable bacteria in food for health benefits, the fermentation process of dairy products and bacteria involved has received great attention over the decades. At the beginning of the last century first scientific work had been done by Metchnikoff to investigate the benefi- cial effects of fermented milk for human health (Caramia and Silvi, 2011). There are now products with complete supplementation offered as medical foods, as well as healthy products for people who have prob- lems obtaining all the nutrients they need (Coman et al., 2012; Ogbonna et al., 2011). It is clear from the literature that new kinds of fermented milks containing various nutrients are being tested as curatives for spe- cific diseases and are approaching medical food effectiveness in conven- tional food format and will continue to be introduced to the food supply. Functional dairy products offer requirements, benefits to health that are strengthened by the addition of probiotics as well as by certain types of soluble fibers known as prebiotics. Established amounts for food fibers are at least 3–6% (w/w) in solid foods and 1.5–3% (w/w) in liquid foods (ANVISA, 2002). Also FAO/WHO (2002) has adopted the defini- tion of probiotics as “Live microorganisms which when administered in adequate amounts confer a health benefit on the host”. Prebiotics, on the other hand, are non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon and thus improve International Journal of Food Microbiology 167 (2013) 261–268 ⁎ Corresponding author at: School of Advanced Studies, at School of Biosciences and Biotechnologies, Via Gentile III da Varano, Camerino 62032, Italy. Tel.: +39 0737402737; fax: +39 0737402418. E-mail address: magda.coman@unicam.it (M.M. Coman). 0168-1605/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ijfoodmicro.2013.09.015 Contents lists available at ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro