title: Enzyme stability of microencapsulated Bifidobacterium animalis ssp. lactis Bb12 after freeze drying and during storage in low water activity at room temperature.
abstract: Stability of enzymes such as β-galactosidase (β-gal), β-glucosidase (β-glu), lactate dehydrogenase (LDH), pyruvate kinase (PK), hexokinase (HK), and ATPase of microencapsulated Bifidobacterium animalis ssp. lactis Bb12 after freeze-drying and after 10 wk of storage at low water activity (a(w)) at room temperature was studied. Bacteria were microencapsulated using alginate formulation with or without mannitol fortification (sodium alginate and mannitol [SAM] and sodium alginate [SA], respectively) by creating gel beads followed by freeze drying. Two types of dried gel beads were then stored at low a(w), such as 0.07, 0.1, and 0.2; storage in an aluminum foil was used as control. All storage was carried out at room temperature of 25 °C for 10 wk. Measurement of β-gal, β-glu, LDH, PK, HK, and ATPase (with or without exposure to pH 2.0 for 2 h) activities was carried out before freeze drying, after freeze drying, and after 10 wk of storage. There was a significant decrease in almost all enzyme activities, except that of PK. SAM and SA showed no different effect on maintaining enzyme activities during freeze drying. Storage for 10 wk at room temperature at various low a(w) using SAM and SA system had a significant effect on retention of most enzymes studied, except that of PK and LDH. Storage at a(w) of 0.07 and 0.1 was more effective in maintaining enzyme activities than storage at a(w) of 0.2 and in an aluminum foil. However, mannitol fortification into alginate system did not significantly improve retention of enzymes during 10 wk of storage.
authors.affiliation: School of Biomedical and Health Sciences, Victoria Univ., Werribee Campus, P.O. Box 14428, Melbourne, Victoria 8001, Australia.
authors.forename: Dianawati
authors.initials: D
authors.lastname: Dianawati
authors.forename: Nagendra P
authors.initials: NP
authors.lastname: Shah
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism; D000464:Alginates / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001644:Bifidobacterium / Q000201:enzymology*; D004655:Emulsions; D004795:Enzyme Stability; D005524:Food Technology; D005612:Freeze Drying; D005782:Gels; D020723:Glucuronic Acid / Q000737:chemistry; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000378:metabolism; D006603:Hexuronic Acids / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008353:Mannitol / Q000737:chemistry; D008863:Microspheres; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000378:metabolism; D019936:Probiotics / Q000737:chemistry / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000032:analysis
chemical_list: D000464:Alginates; D001426:Bacterial Proteins; D004655:Emulsions; D005782:Gels; D006603:Hexuronic Acids; D014867:Water; D008353:Mannitol; D020723:Glucuronic Acid; D017853:Phosphotransferases (Alcohol Group Acceptor); D006026:Glycoside Hydrolases; D000251:Adenosine Triphosphatases