Proteolysis enhancement of cheddar cheese and enzyme -modified cheese by free or encapsulated form of natural and recombinant enzymes of Lactobacillus rhamnosus S93

A recombinant aminopeptidase (pepN) of Lactobacillus rhamnosus S93 was encapsulated in chitosan-coated alginate beads using an extrusion method. The effects of alginate, CaCl2, chitosan concentrations, hardening time, pH, and alginate/enzyme ratios on the encapsulation efficiency (EE) and the enzyme release (ER) were then investigated. Chitosan in the gelling solution significantly increased the encapsulation efficiency (EE) and also retarded the enzyme release (ER) from the beads. The greatest EE was observed in a pH 5.4 solution (chitosan-CaCl2) during bead formation. Increasing the CaCl2 concentration over 0.1 M neither affected the EE nor the ER. Increasing the hardening time beyond 10 min led to a decrease in EE and alginate:enzyme ratio (3:1) was optimal to prevent the ER.;The application of natural and recombinant enzymes of Lactobacillus rhamnosus S93 was also investigated to develop a process of Cheddar-EMC flavorings. Water soluble nitrogen, PTA-N and FAA levels were significantly higher in the proteinase (Neutrase) added EMCs. The highest levels of PTA-N and FAA were evident in samples containing the highest levels of combined natural and recombinant enzymes. Proline disappeared in the experimental EMCs compared to the control over maturation times.;Using the free or encapsulated fowl of the recombinant pepN at three different concentrations (50, 500, 2000 units 18 L-1 milk), control and experimental cheeses were prepared in vats containing 18 L milk. The effects of two enzyme forms at the similar concentration were also investigated in larger scale of cheesemaking trial (200 L milk). The amounts of nitrogen soluble in phosphotungstic acid (PTA-N) and free amino acids (FAA) were enhanced by increasing the enzyme concentration. While proline disappeared at 4 months of ripening period, leucine was the most dominant amino acid in the experimental cheeses. Cheese with the encapsulated enzyme at the highest concentration received significantly higher mean levels of PTA-N and total FAAs than the other cheeses. The use of encapsulated enzyme resulted in an acceleration of 70% in proteolysis and superior sensory properties than the control cheese. Almost all encapsulated enzymes were entrapped into the cheese matrix, revealing the stability of the capsules during Cheddar cheese manufacturing.