CHEMICAL ENGINEERING TRANSACTIONS VOL. 38, 2014 A publication of The Italian Association of Chemical Engineering www.aidic.it/cet Guest Editors: Enrico Bardone, Marco Bravi, Taj Keshavarz Copyright © 2014, AIDIC Servizi S.r.l., ISBN 978-88-95608-29-7; ISSN 2283-9216 Addition of Strawberry, Raspberry and “Pitanga” Pulps Improves the Physical Properties of Symbiotic Yoghurts Luciana Bueno, Thamires M. S. Silva, Natália P. Perina, Cristina Bogsan, Maricê N. Oliveira * Department of Biochemical and Pharmaceutical Technology, University of São Paulo, Av. Prof Lineu Prestes, 580, Bl.16, 05508-900, São Paulo, Brazil monolive@usp.br The health benefits offered by probiotic fermented milks can be increased by adding native fruit pulps. Red fruits contain ellagic acid (EA) and ellagitannins, interesting substances due to their powerful antioxidant properties and other beneficial biological activities, such as cardio protective effects, selective growth inhibition of human pathogenic bacteria, Į-amylase inhibition of angiotensin I converting enzyme, and proliferative activities against several different cancer cells. This study aimed to improve the physical properties of symbiotic yoghurts through their supplementation with a mixture of red berry pulps: strawberry, raspberry and “pitanga”. The simplex-centroid design was used for mixture modelling. The design included seven batches/trials: three supplemented with each type of fruit pulp, three corresponding to the binary mixtures and one supplemented with the combination of the three pulps. A control experiment was prepared without addition of fruit pulp. Processed milk bases were fermented at 42 °C until pH 4.7 by using a starter culture blend that consisted of Streptococcus thermophilus (TA040), Lactobacillus bulgaricus (LB340) and Lactobacillus acidophilus (LA140). Subsequently, milk base (80 %) was blended with a pulp preparation (20 %) and other ingredients according to the experimental design. Physico- chemical analyses, enumeration of viable bacteria, colour and rheological characteristics of the yoghurts were evaluated 36 h after preparation and 21 days after cold storage. Three regression models were adjusted to the results (linear, quadratic and cubic special). The results showed that the addition of a mixture of red fruit pulps affected pH and counts of probiotic bacteria, which slightly decrease during storage. Addition of the three red berry pulps simultaneously enhanced the colour and rheological properties of probiotic yoghurts when compared to the control. It was possible to estimate the optimum mixture compositions of the three fruit pulps that increase EA contents in probiotic yoghurts. 1. Introduction Probiotics are living microorganisms that, confer numerous health benefits to the host when they are supplied in adequate amounts (FAO/WHO, 2002). These microorganisms interact with intestine bacterial flora favoring the presence of beneficial bacteria and reducing the concentration of undesirable bacteria and microorganisms (Fuller, 1991), therefore improving intestinal balance. Prebiotics are substances that, given their structure, they are only fermented in the colon by endogenous bacteria that improve bowel function by stimulating the growth of beneficial bacteria. The presence of beneficial bacteria has specific effects on gastrointestinal physiology, mineral bioavailability, immune system, genesis regulation of tumors and serum cholesterol. From all available prebiotics, only fructooligosaccharides (FOS) and inulin can be considered as active components of functional foods (Douglas and Sanders, 2008; Roberfroid et al., 2010; Oliveira et al., 2012). Consequently, those products containing probiotics and prebiotics in their formulation (symbiotic products) are increasing in popularity and acceptance worldwide (da Cruz et al., 2007; Siro et al., 2008; Oliveira et al., 2011; Oliveira, Perego, et al., 2011). Numerous studies have shown that several fruits increase the nutritional value to food, because they are potential beneficial for human health (Espírito Santo et al., 2011). Among the bioactive compounds present DOI: 10.3303/CET1438084 Please cite this article as: Bueno L., Silva T.M.S., Perina N., Bogsan C., Oliveira M., 2014, Addition of strawberry, raspberry and “pitanga” pulps improves the physical properties of symbiotic yoghurts, Chemical Engineering Transactions, 38, 499-504 DOI: 10.3303/CET1438084 499