Using ultrasonic vacuum spray dryer to produce highly viable dry probiotics David Semyonov, Ory Ramon, Eyal Shimoni * Faculty of Biotechnology and Food Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel article info Article history: Received 25 October 2009 Received in revised form 17 March 2011 Accepted 18 March 2011 Keywords: Spray dryer Probiotic Microencapsulation Storage abstract Ultrasonic vacuum spray dryer was used to produce a dry powder of highly viable probiotic cells. The drying was performed through two stages: Vacuum spray drying of the solution followed by fluidized- bed drying of the powder. The embedding matrix was a combination of trehalose and maltodextrin. The effects of external and internal variables on cell survival during the drying process and storage were investigated. The hypothesis was that by minimizing the oxidative and thermal stresses in the drying stages, in addition to adequate formulation choice, the cell viability during the drying and storage will increase. It was concluded that during the drying process the faster the embedding matrix reaches a glassy state the higher was the probiotic survival. Evaluating water activity and moisture limit of the glassy matrix concluded that maltodextrin DE5 is a better encapsulating matrix than maltodextrin DE19. Combining trehalose to maltodextrin in the encapsulating matrix resulted in a significant increase in the survival up to 70.6  6.2%. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Probiotics are described as “live micro-organisms which when administered in adequate numbers confer a health benefit on the host” (FAO/WHO, 2001). They are commonly included in fermented milks, yoghurts and cheese, but are also available in the form of dietary supplements where the probiotic is in the form of a dried product. Probiotic-containing foods can be categorized as functional foods, and along with prebiotics represent the largest segment of the functional foods market in Europe, Japan and Australia. The market for this food category continues to expand, in parallel with growing consumer awareness of the role of diet in health mainte- nance (Berner & O’Donnell, 1998; Stanton et al., 2001). Probiotics such as Lactobacillus and Bifidobacteria species are added to foods mainly to improve intestinal microbial balance. Lactobacillus, a genus of Gram-positive facultative anaerobic bacteria, are a major part of the Lactic Acid Bacteria group. Such probiotics are common and usually benign, even essential, inhabi- tants of humans and other animals. Lactobacillus and Bifidobacte- rium species are the most commonly used probiotics in foods for human consumption given the significant health benefits associated with ingestion of these micro-organisms. These micro-organisms share a number of common traits, such as generally regarded as safe (GRAS) status, acid and bile tolerance, and ability to adhere to intestinal cells (Dunne et al., 2001). It is recommended that the probiotic culture must be present in the product at minimum numbers of 10 7 CFU/ml and even higher numbers have been rec- ommended (Ishibashi & Shimamura, 1993; Lee & Salminen, 1995). Probiotic cultures for food applications are frequently supplied in frozen or dried form, either as freeze-dried or spray-dried powders (Lievense & Van’t Riet,1993; Holzapfel, Haberer, Geisen, Bjorkroth, & Schillinger, 2001). Relatively successful drying of lactobacilli and bifidobacteria has previously been reported for a number of different strains (Goderska & Czarnecki, 2008), including Lactoba- cillus paracasei (Gardiner et al., 2000). An adequate solution to improve probiotic survival during their processing is their micro- encapsulation (Shah & Ravula, 2000). In order to extend the pro- biotic storage stability, techniques such as spray drying, freeze drying and fluidized bed spray coating were employed resulting in a dry powder. However, most probiotic lactobacilli do not survive well during the temperature and osmotic extremes to which they are exposed during the conventional drying and encapsulation processes (Goderska & Czarnecki, 2008; Ross, Desmond, Fitzgerald, & Stanton, 2005). The energy consumption of spray drying is 6e10 times lower compared to freeze drying, since both mass and energy are fast transferred in a very short time without using an exchange surface (Knorr, 1998). Spray drying technique was applied mostly in dairy industry and in food products where original properties can be preserved. However the use of spray drying to produce dry pro- biotics is questionable because of high bacterial mortality due to simultaneous dehydration, thermal and oxygen stresses imposed * Corresponding author. Tel.: þ972 4 8292484; fax: þ972 4 8293399. E-mail address: eshimoni@tx.technion.ac.il (E. Shimoni). Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt 0023-6438/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.lwt.2011.03.021 LWT - Food Science and Technology 44 (2011) 1844e1852