use of hydro-lysates from thunnus tonggol viscera as a peptone for listeria monocytogenes gowth media

the objective of this study was to produce fish peptone from tuna (thunnus tonggol) viscera, by alcalase. response surface methodology (rsm) was employed for optimizing the temperature and ph. hydrolysis was done in different tempratures (50-65˚c) , ph (8-8. 5) and selected 13 treatments. samples with higher value of protein were used instead of the standard peptones which applied in commercial media for listeria monocytogenes. based on the three-dimensional graphs, the optimum condition for temperature and ph were determined to be 50˚c and 8. 5 respectively. the results showed that the highest (76. 89 g/l) and the lowest (38. 54 g/l) rates of protein content were related to ph 8 at 57˚c and ph 8 at 50˚c. maximum bacterial growth rate was related to ph 8 at 65˚c. results also showed that tuna (thunnus tonggol) viscera can be used as low cost nitrogen sources for listeria monocytogenes growth media.