Predictive model for the growth of Yersinia enterocolitica under modified atmospheres

A quadratic response surface model is presented to describe the maximum spe cific growth rate of Yersinia enterocolitica, at refrigeration temperatures , under modified atmospheres. The presence of CO2 affected mainly the lag p hase of the organism. The length of the lag phase increased with higher lev els of CO2 in the atmosphere, and this effect was more noticeable at low te mperatures. The effect of oxygen was similar but less pronounced. The obser ved growth was slower with higher CO2. Oxygen also decreased the growth rat e, but its effect was significant only when its proportion in the atmospher e was greater than about 40%. Model predictions were compared with growth r ates obtained in sea food inoculated with Y. enterocolitica and packaged un der modified atmospheres. Predictions were also checked to determine whethe r they were inside the strict interpolation region of the model.