Growth/no-growth modeling to control the spoilage of chocolate cake by Penicillium citrinum LMQA_053: Impact of pH, water activity, temperature, and different concentrations of calcium propionate and potassium sorbate

The objective of this study was to determine the probabilities of spoilage of different formulations of cakes varying pH, preservatives, and water activity (a_w) at different storage temperatures by Penicillium citrinum LMQA_053. Cake were produced with different a_w values (0.78, 0.80, 0.83 and 0.86), pH (6.0; 6.3; 6.6 and 7.0), calcium propionate (0%, 0.10%, 0.15% and 0.20%) and potassium sorbate (0%, 0.05% and 0.10%). Then, cakes were inoculated with P. citrinum LMQA_053 and stored at 20, 25, and 30 °C. The logistic regression model was adjusted to growth/no-growth results to obtain predictions of growth probability. The probabilistic model presented 83% of agreement with the observed results. A chocolate cake formulation combining low aw (<0.78) and the highest concentration of preservatives (0.1% potassium sorbate, 0.2% calcium propionate) could prevent the growth of P. citrinum LMQA-053 in all pH and temperatures assessed for 45 days. The developed model was able to predict the growth probability of P. citrinum LMQA_053 and can be used to develop more robust formulas towards avoiding mould growth and spoilage of cakes.