The release profiles of nisin from nisin-incorporating gel foods and the antimicrobial activities of the gels on the growth of Brochothrix thermosphacta in an aqueous system containing the gels have been investigated. A linear regression model was applied to determine the diffusion coefficient (D) for the diffusion of nisin in the gel. The antimicrobial activities of nisin released from 1, 2 and 3% (w/v) agar gels on the growth of B. thermosphacta in a broth medium with and without nisin were investigated. The D decreased from 1.2×10 -2 to 8.2×10 -3 and 6.4×10 -3 cm 2 /s as the agar concentration in the gel increased from 1 to 2 and 3% (w/v), demonstrating the diffusion rate in the gels can be controlled by the agar concentration in gel. The agar gel incorporating nisin inhibited the B. thermosphacta growth in the broth medium by prolonging the lag phase. The growth inhibition was enhanced by the addition of nisin in the medium. The results of this study exhibited that the gel food is a feasible nisin delivery system with a controlled release achieved by the adjustment of agar concentration in the system, demonstrating the potential of nisin-incorporating gel for preserving particulate-containing drinks.

• Yicheng Zong(Department of Food Science, University of Manitoba)
• Jung Hoon Han(Pulmone Foods USA, Fullerton, California, USA)
• Yeong Ji Oh(Department of Food Science and Technology, Seoul Women’s University)
• Sea C. Min(Department of Food Science and Technology, Seoul Women’s University) Corresponding author