Effect of double alginate microencapsulation on in vitro digestibility and thermal tolerance of Lactobacillus plantarum NCDC201 and L. casei NCDC297 Sajad A. Rather, Rehana Akhter, F.A. Masoodi * , Adil Gani, S.M. Wani Department of Food Science and Technology, University of Kashmir, Srinagar 190006, India article info Article history: Received 24 November 2016 Received in revised form 11 April 2017 Accepted 12 April 2017 Available online 15 April 2017 Keywords: Probiotics Microencapsulation Sodium alginate Survivability Thermal treatment abstract This study was undertaken for the microencapsulation of Lactobacillus plantarum NCDC201 and L. casei NCDC297 into double alginate coatings. Microencapsulated probiotics showed significant improvement in their survivability after simulated gastrointestinal passage and exposure to heat treatments. The resistance in simulated gastric juice (SGJ) (120 min) was 47.50% and 45.82% higher as compared to free cells of L. plantarum NCDC201 and L. casei NCDC297, respectively. After incubation in simulated intestinal juice (SIJ) (120 min), the viable probiotic population was 6.34 log CFU/ml and 6.92 log CFU/ml for microencapsulated L. plantarum NCDC201 and L. casei NCDC297, respectively. Similarly, micro- encapsulated probiotics showed relevant counts at higher heat exposure (75  C for 1 and 10 min). SEM results indicated the absence of free bacteria confirming the formation of microcapsules, with spherical morphology, continuous and compact surfaces. ATR-FTIR analysis confirmed the cross linking of the microcapsules by calcium chloride and successful immobilization of the probiotics into the polymer microcapsules. DSC suggested the formation of cross-linking and structure of “egg box” and increase in the melting temperature of microcapsules. This study has concluded that double alginate coating technique enhanced the stability of probiotics at high temperature (75 ± 1  C) and in simulated gastric and intestinal conditions. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction During the recent past, there has been raising demand for functional foods. Probiotics are considered the important compo- nents of health promoting functional foods. These are defined as “live microorganisms which, when administered in adequate amounts, confer a health benefit beyond basic nutrition on the host” (FAO/WHO, 2001) and have become increasingly popular during the last decade. The major health promoting effects of probiotics include control of serum cholesterol levels and intestinal infection, which beneficially influence the immune system, improving lactose utilization and anticarcinogenic activity (Fritzen- Freire et al., 2013; Shah, Gani, Ahmad, Ashwar, & Masoodi, 2016). In order to derive the health benefits from probiotic bacteria, it has been recommended that they must be present at a minimum level of 10 6 CFU/g of food product (Doleyres & Lacroix, 2005) or 10 7 CFU/ g at a point of delivery (Lee & Salminen, 1995) or to be eaten in sufficient amounts to yield a daily intake of 10 8 CFU/g (Lopez-Rubio, Gavara, & Lagaron, 2006). However, a major challenge in the incorporation of probiotic bacteria in foods is the retention of their viability during processing of foods (Granato, Branco, Cruz, Faria, & Shah, 2010; Pop, Brandau, Schwinn, Vodnar, & Socaciu, 2015). Because processing leads to loss of their viability as probiotic bacterial cells are thermally labile and sensitive to acidity, oxygen and higher salt concentrations. Further probiotic bacteria can impart their beneficial effects in the colon of host, it is essential to maintain their viability during which they have to overcome barriers like low gastric pH and bile salts (Kim et al., 2008). To overcome such deficiencies, microencapsulation techniques are promising prospect for enhancing the resistance of probiotic cells against harsh environmental conditions in order to maintain their viability, activity and functionality. Microencapsu- lation matrix provides a physical barrier against stress conditions (Ch avarri et al., 2010), maintains their viability during passage through the gastrointestinal tract until they reach their target destination, where they should break down and release the * Corresponding author. E-mail address: masoodi_fa@yahoo.co.in (F.A. Masoodi). Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt http://dx.doi.org/10.1016/j.lwt.2017.04.036 0023-6438/© 2017 Elsevier Ltd. All rights reserved. LWT - Food Science and Technology 83 (2017) 50e58