title: Factors affecting viability of Bifidobacterium bifidum during spray drying.
abstract: BACKGROUND
  There is substantial clinical data supporting the role of Bifidobacterium bifidum in human health particularly in benefiting the immune system and suppressing intestinal infections. Compared to the traditional lyophilization, spray-drying is an economical process for preparing large quantities of viable microorganisms. The technique offers high production rates and low operating costs but is not usually used for drying of substances prone to high temperature. The aim of this study was to establish the optimized environmental factors in spray drying of cultured bifidobacteria to obtain a viable and stable powder.
  
  
  METHODS
  The experiments were designed to test variables such as inlet air temperature, air pressure and also maltodextrin content. The combined effect of these variables on survival rateand moisture content of bacterial powder was studied using a central composite design (CCD). Sub-lethal heat-adaptation of a B. bifidum strain which was previously adapted to acid-bile-NaCl led to much more resistance to high outlet temperature during spray drying. The resistant B. bifidum was supplemented with cost friendly permeate, sucrose, yeast extract and different amount of maltodextrin before it was fed into a Buchi B-191 mini spray-dryer.
  
  
  RESULTS
  Second-order polynomials were established to identify the relationship between the responses andthe three variables. Results of verification experiments and predicted values from fitted correlations were in close agreement at 95% confidence interval. The optimal values of the variables for maximum survival and minimum moisture content of B. bifidum powder were as follows: inlet air temperature of 111.15°C, air pressure of 4.5 bar and maltodextrin concentration of 6%. Under optimum conditions, the maximum survival of 28.38% was achieved while moisture was maintained at 4.05%.
  
  
  CONCLUSIONS
  Viable and cost effective spray drying of Bifidobacterium bifidum could be achieved by cultivating heat and acid adapted strain into the culture media containing nutritional protective agents.
authors.affiliation: Department of Chemical Engineering, Islamic Azad University-Tehran South Branch, Tehran, Iran. zahrashokri@yahoo.com.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Shokri
authors.affiliation: Probiotic Research Laboratory, Department of Drug and Food Control, Pharmaceutical Sciences Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran. morfazeli@yahoo.com.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Fazeli
authors.affiliation: Department of Chemical Engineering, Islamic Azad University-Tehran South Branch, Tehran, Iran. m_arjmand@azad.ac.ir.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Ardjmand
authors.affiliation: Biotechnology Group, Chemical Engineering Department, Tarbiat Modares University, Tehran, Iran. mousavi_m@modares.ac.ir.
authors.forename: Seyyed Mohammad
authors.initials: SM
authors.lastname: Mousavi
authors.affiliation: Aerosol Research Laboratory, Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran. gilani@tums.ac.ir.
authors.forename: Kambiz
authors.initials: K
authors.lastname: Gilani
mesh_terms: D000399:Air Pressure; D001644:Bifidobacterium / Q000502:physiology*; D003470:Culture Media / Q000737:chemistry; D003890:Desiccation / Q000295:instrumentation / Q000379:methods*; D004355:Drug Stability; D006801:Humans; D050296:Microbial Viability; D011134:Polysaccharides / Q000032:analysis*; D011208:Powders; D019936:Probiotics; D013696:Temperature
chemical_list: D003470:Culture Media; D011134:Polysaccharides; D011208:Powders; C008315:maltodextrin