Predictive microbiology

Fitting a reparameterised Gompertz growth model using R

Using the data set “gomp1.csv”, find the parameters of the reparameterised Gompertz model. \[\begin{equation} y= y_0 + (y_{max} -y_0)*exp(-exp(k*(lag-x)/(y_{max}-y_0) + 1) ) \end{equation}\] Import the data set. dat <- read.csv("gomp1.csv", sep=";", header=T) plot(dat$Time, dat$logN) str(dat) ## 'data.frame': 13 obs. of 2 variables: ## $ Time: int 0 2 4 6 8 10 12 14 16 18 ... ## $ logN: num -0.105 0.108 -0.111 0.734 2.453 ... The next step is define the Gompertz function.

Fitting a first-order or loglinear growth model using R

The data set “FirstOrder.csv” contains observations of microbial concentrations (log N) measured at different times (t) at a given environmental condition. Lets fit a first-order growth kinetics model \(log N = log N_0 + k \times t\) to the experimental data. Let’s import the “FirstOrder.csv” dataset, and observe the first five lines. dat <- read.csv("FirstOrder.csv", sep=";", header=TRUE) dat ## Time N ## 1 0 37.298 ## 2 1 56.149 ## 3 2 81.

A comparison of dynamic tertiary and competition models for describing the fate of Listeria monocytogenes in Minas fresh cheese during refrigerated storage

This study compares dynamic tertiary and competition models for L. monocytogenes growth as a function of intrinsic properties of a traditional Brazilian soft cheese and the inhibitory effect of lactic acid bacteria (LAB) during refrigerated storage. …