Please cite this article in press as: I. Trabelsi, et al., Int. J. Biol. Macromol. (2013), http://dx.doi.org/10.1016/j.ijbiomac.2013.06.035 ARTICLE IN PRESS G Model BIOMAC 3803 1–7 International Journal of Biological Macromolecules xxx (2013) xxx–xxx Contents lists available at SciVerse ScienceDirect International Journal of Biological Macromolecules jo ur nal homep age: www.elsevier.com/locate/ijbiomac Encapsulation in alginate and alginate coated-chitosan improved the survival of newly probiotic in oxgall and gastric juice Imen Trabelsi, Wacim Bejar, Dorra Ayadi, Hichem Chouayekh, Radhouane Kammoun, Q1 Samir Bejar, Riadh Ben Salah ∗ Laboratory of Microorganisms and Biomolecules (LMB), Centre of Biotechnology of Sfax, University of Sfax, Road of Sidi Mansour Km 6, P.O. Box 1177, Sfax 3018, Tunisia a r t i c l e i n f o Article history: Received 17 May 2013 Received in revised form 13 June 2013 Accepted 22 June 2013 Available online xxx Keywords: Microencapsulation Alginate Chitosan a b s t r a c t This study was undertaken to develop an optimum composition model for the microencapsulation of a newly probiotic on sodium alginate using response surface methodology. The individual and interactive effects of three independent variables, namely sodium alginate concentration, biomass concentration, and hardening time, were investigated using Box–Behnken design experiments. A second ordered poly- nomial model was fitted and optimum conditions were estimated. The optimal conditions identified were 2% for sodium alginate, 10 10 UFC/ml for biomass, and 30 min for hardening time. The experimental value obtained for immobilized cells under these conditions was about 80.98%, which was in close agreement with the predicted value of 82.6%. Viability of microspheres (96%) was enhanced with chitosan as coating materials. The survival rates of free and microencapsulated Lactobacillus plantarum TN8 during exposure to artificial gastrointestinal conditions were compared. The results revealed that the encapsulated cells exhibited significantly higher resistances to artificial intestinal juice (AIJ) and artificial gastric juice (AGJ). Microencapsulation was also noted to effectively protect the strain from heating at 65 ◦ C and refrigerating at 4 ◦ C. Taken together, the findings indicated that microencapsulation conferred important protective effects to L. plantarum against the gastrointestinal conditions encountered during the transit of food. © 2013 Published by Elsevier B.V. 1. Introduction Although antibiotics have several beneficial effects, their exces- sive use contributes to the development of resistance to pathogenic microorganisms [1] This has led in 2006 the European Union to ban the use of antibiotics as growth promoters in animal husbandry [2] and initiated a continuous global search for alternative strategies. During the past few decades, probiotics have often been proposed as a promising alternative. Probiotics are defined as “a live micro- bial supplements that beneficially affects the health of the host by improving the balance of the microflora in the intestinal tract” [3,4]. Due to their multiple health benefits, probiotic bacteria have been incorporated into various dairy products, including soft and hard cheeses, ice cream, yoghurt, frozen dairy desserts, and animal feed [5]. The main probiotic microorganisms known to date are members of two genera of lactic acid bacteria (LAB), namely Lac- tobacillus and Bifidobacterium. In fact, foods containing probiotic bacteria belong to the class of “functional foods”. The latter contain ∗ Corresponding author at: Laboratoire de Microorganismes et de Biomolécules (LMB), Centre de Biotechnologie de Sfax, Route de Sidi Mansour Km 6, BP “1177”, 3018 Sfax, Tunisia. Tel.: +216 74 87 04 51; fax: +216 74 87 04 51. E-mail addresses: riadh fss@yahoo.fr, riadh.bensalah@cbs.rnrt.tn (R. Ben Salah). at least 10 7 CFU/g of probiotic bacteria and should be consumed at levels higher than 100 g/day to have beneficial effects on health [5] One of the most versatile and flexible LAB species is Lactobacillus plantarum, which has a moderate acid tolerance, a homofermenta- tive metabolism, and a valued GRAS (Generally Recognized as Safe) status. Accordingly, several strains of L. plantarum are marketed as probiotics in food technology [6]. In fact, new bacterial probiotic strains for use in animal feed are typically submitted to viability tests under standard gastrointestinal, processing, and storage con- ditions [7]. There are still, however, a number of problems related to the low survival of probiotic bacteria under gastrointestinal condi- tions, particularly in animal feed [8]. This has encouraged the search for new efficient techniques to improve the survival of probiotics [9]. Recent research indicates that the microencapsulation of pro- biotic cells presents one of the most promising and efficient techniques for the enhancement of probiotic survival. The effec- tiveness of microencapsulation for the delivery of viable probiotic bacteria in food products derives from the physical barrier against stress conditions supplied by the encapsulation matrix [10]. This ensures that capsules maintain their integrity during passage through the gastrointestinal tract until they reach their target des- tination (colon), where they break down and release probiotic bacteria [11]. These techniques have also often used to protect 0141-8130/$ – see front matter © 2013 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.ijbiomac.2013.06.035 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59