Response surface method in the Synthesizing of nutrient broth with predetermined pH and water activities

Abstract

Polynomial models describing the individual and combined influences of solutes (sucrose and NaCl) and 
pH on the water activity (aw) of nutrient broth systems (NBS) were established using Response Surface 
Methodology. For the sucrose-pH model, the linear, quadratic and interactive influences of sucrose 
concentration and pH significantly affected aw; while only the linear and quadratic influences of NaCl 
and pH significantly affected aw in NaCl-pH model. The resulting models were characterized with 
satisfactory goodness- of-fit and efficient predictive performance. The established models may be used 
in the estimation of NBS components to formulate growth media with desired physicochemical property 
combinations and may be applied when studying microbial behaviors such as in quantitative microbial 
ecology.