Predictive food microbiology(PFM) is an emerging area of food microbiology since the later 1980's. It does apply mathematical models to predict the responses of microorganism to specified environmental variables. Although, at present, PFM models do not completely developed, models can provide very useful information for microbiological responses in HACCP(Hazard Analysis Critical Control Point) system and Risk Assessment. This study illustrates the possible use of PFM models(PMP: Pathogen Modeling Program win5.1) with milk in several elements in the HACCP system, such as conduction of hazard analysis and determination of CCP(Critical Control Points) and CL(Critical Limits). The factors likely to affect the growth of the pathogens in milk involved storage temperature, pH, Aw and NaCl content. The variable factor was storage temperature at the range of 4-15℃ and the fixed factors were pH 6.7, Aw 0.993 and NaCl 1.3%. PMPwin5.1 calculated generation time, lag phase duration, time to level of infective dose for pathogens across a range of storage temperature. The levels of safety associated with milk which were defined based on various storage temperature as affecting microbial growth according to PMPwin5.1 were classified in $quot;safe temperature zone$quot;, $quot;caution temperature zone$quot; and $quot;danger temperature zone$quot;, respectively. These zone ranges were determined by the lag phase duration and time to level of infective dose based on shelf life of milk, which is required 5 days in domestic legal. These results can be used to conduct a hazard analysis and set the criteria for CCP or CL. Though PFM contains limitation in the use, PFM models can be useful instrument to support of guarantee of food safety.

The aim of this study was to investigate the growth of aerobic bacteria in fresh-cut salad during short-term temperature abuse (4∼30℃temperature for 1, 2, and 3 h) for 72 h and to develop predictive models for the growth of total viable cells (TVC) based on Predictive food microbiology (PFM). The tool that was used, Pathogen Modeling program (PMP 7.0), predicts the growth of Aeromonas hydrophila (broth Culture, aerobic) at pH 5.6, NaCl 2.5%, and sodium nitrite 150 ppm for 72 h. Linear models through linear regression analysis; DMFit program were created based on the results obtained at 5, 10, 20, and 30℃ for 72 h (r2 >0.9). Secondary models for the growth rate and lag time, as a function of storage temperature, were developed using the polynomial model. The initial contamination level of fresh-cut salad was 5.6 log CFU/mL of TVC during 72 h storage, and the growth rate of TVC was shown to be 0.020∼1.083 CFU/mL/h (r2 >0.9). Also, the growth tendency of TVC was similar to that of PMP (grow rate: 0.017∼0.235 CFU/mL/h; r2=0.994∼1.000). The predicted shelf life with PMP was 24.1∼626.5 h, and the estimated shelf life of the fresh-cut salads with short-term temperature abuse was 15.6∼31.1 h. The predicted shelf life was more than two times the observed one. This result indicates a ‘fail safe’ model. It can be taken to a ludicrous extreme by adopting a model that always predicts that a pathogenic microorganism will grow even under conditions so strict as to be actually impossible.