Microencapsulation of a recombinant aminopeptidase (PepN) fromLactobacillus rhamnosusS93 in chitosan-coated alginate beads

Effect of free and encapsulated recombinant aminopeptidase on proteolytic indices and sensory characteristics of Cheddar cheese

“…After filtration, the beads were washed with deionized distilled water to remove the untrapped enzyme and excess calcium chloride from the surface of the beads. Portions (1 g; wet weight) of coated or uncoated beads were then dissolved under gentle agitation (70 rpm) in 10 mL of trisodium citrate (20 g L À1 ) release buffer, at room temperature (Azarnia et al, 2008). After complete dissolution of the beads, the enzyme activity in the release buffer was measured.…”

“…Portions (1 g) of crab shell chitosan (85% deacetylated) were dissolved in 700 mL of 0.1 mol L À1 glacial acetic acid and stirred overnight (Azarnia et al, 2008). After complete dissolution, the pH was then adjusted to 5.4 with NaOH (1 mol L À1 ).…”

“…Recombinant aminopeptidase (PepN) from L. rhamnosus S93 was prepared and purified as described by Azarnia, Lee, Robert, and Champagne (2008). The E. coli clones containing the gene for aminopeptidase (PepN) of L. rhamnosus S93 were obtained from the Agriculture & Agri-Food Canada, Food R & D Centre (St-Hyacinthe, PQ, Canada).…”

“…CaCl 2 . H 2 O (14.7 g) was added to the chitosan solution and the volume adjusted to 1L with deionized distilled water, yielding a cationic solution of 1 g chitosan L À1 in (0.1 mol L À1 ) CaCl 2 (Azarnia et al, 2008). The purified recombinant aminopeptidase and the cooled Na-alginate (Sobalg FD 126, Grindsted Products, Inc., Rexdale, ON, Canada) solution (18 g L À1 ) at a ratio of 1:3 were mixed gently for 2 min.…”

“…Leucine-p-nitroanilide dissolved in methanol to a final concentration of 16.4 mmol L À1 was used as a substrate (Azarnia et al, 2008). The reaction mixture consisting of 10 mL of enzyme solution, 10 mL of leucine-p-nitroanilide, 10 mL of cobalt chloride solution (20 mmol L À1 ) and 170 mL of potassium phosphate buffer (0.05 mol L À1 , pH 7.5) was incubated at 37 C for 30 min.…”