Contents lists available at ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro Passion fruit by-product and fructooligosaccharides stimulate the growth and folate production by starter and probiotic cultures in fermented soymilk Marcela Albuquerque Cavalcanti Albuquerque a,b , Raquel Bedani a,b , Jean Guy LeBlanc c , Susana Marta Isay Saad a,b,⁎ a Departamento de Tecnologia Bioquímico-Farmacêutica, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 580, 05508-000 São Paulo, SP, Brazil b Food Research Center, University of São Paulo, São Paulo, Brazil c CERELA-CONICET, C.P. T4000ILC, San Miguel de Tucumán, Argentina ARTICLE INFO Keywords: Folate Probiotic Passion by-product FOS Fermented soymilk ABSTRACT Two starter cultures (Streptococcus (St.) thermophilus ST-M6 and TA-40) and five probiotic strains (St. thermo- philus TH-4, Lactobacillus (Lb.) acidophilus LA-5, Lb. rhamnosus LGG, Lb. fermentum PCC, and Lb. reuteri RC-14) were used to ferment different soymilk formulations supplemented with passion fruit by-product and/or fructo- oligosaccharides (FOS) with the aim of increasing folate concentrations. Growth and folate production of in- dividual strains were evaluated and the results used to select co-cultures. Both St. thermophilus ST-M6 and TH-4 were the best folate producers and were able to increase the folate content of all soymilk formulations when used alone or in co-culture with lactobacilli strains, especially in the presence of both passion fruit by-product and FOS. Thus, passion fruit by-product and FOS could be used as dietary ingredients to stimulate the folate pro- duction by selected bacterial strains during the fermentation of soymilk. It was also shown that vitamin pro- duction by microorganisms is strain-dependent and may also be influenced by nutritional and environmental conditions. 1. Introduction Soymilk has been shown to be a good medium for the growth of lactic acid bacteria (LAB) and the ability of some Lactobacillus spp. and Streptococcus thermophilus strains in metabolizing oligosaccharides during the fermentation of soymilk has been shown in different studies (Bedani et al., 2013; Champagne et al., 2009; Donkor et al., 2007; Lee et al., 2013). The α-galactosidase activity is present in some LAB and this enzyme contributes to the growth of these microorganisms during the fermentation of soy-based products through the hydrolysis of some carbohydrates, such as raffinose and stachyose. This metabolic me- chanism results on the production of short chain fatty acids by these microorganisms improving intestinal human's health and reducing non- desirable gastrointestinal side-effects caused by soy products (Fung and Liong, 2010; LeBlanc et al., 2008; LeBlanc et al., 2017). Thus, the α- galactosidase activity is an important physiological characteristic pre- sented by lactobacilli and streptococci strains once humans are not able to metabolize soy oligosaccharides. Additionally, it is known that the processing of soybeans may cause the loss of some water soluble nutrients such as folate, a soluble B-group vitamin (Arcot et al., 2002; Mo et al., 2013). On the other hand, the ability of some starter and probiotic cultures, belonging to the LAB's group, in producing folate during fermentative processes has been de- scribed (Albuquerque et al., 2016; Pacheco da Silva et al., 2016). Pro- biotics are “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host” (Hill et al., 2014). Previous studies have shown that selected LAB can be used to in- crease folate content during the fermentation of milks (Gangadharan and Nampoothiri, 2011; Holasová et al., 2005; Laiño et al., 2013; Laiño et al., 2014; Pompei et al., 2007). However, the ability of these mi- croorganisms to produce folate during the fermentation of soymilk supplemented with fruit agro-industrial wastes has not been described yet. Moreover, the use of fermentation as a natural process to bio-enrich soymilks with natural folates produced by food-grade functional mi- croorganisms may be considered as a promising alternative to provide health benefit to consumers and also to increase the economic value of these fermented foods. Considering that the production of folate by microorganisms is http://dx.doi.org/10.1016/j.ijfoodmicro.2017.09.001 Received 27 March 2017; Received in revised form 14 August 2017; Accepted 4 September 2017 ⁎ Corresponding author at: Departamento de Tecnologia Bioquímico-Farmacêutica, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 580, 05508-000 São Paulo, SP, Brazil. E-mail address: susaad@usp.br (S.M.I. Saad). International Journal of Food Microbiology 261 (2017) 35–41 Available online 05 September 2017 0168-1605/ © 2017 Elsevier B.V. All rights reserved. MARK