On Measuring, Modelling and Validating Growth of Surface Molds through Image Analysis in Industrial Salami Ripening

Abstract

This paper reports the development and the results of a procedure aimed at measuring, modelling and validating the growth of surface molds in industrial salami ripening by relying on techniques of image analysis. The sausages under investigation were inoculated with fungal starters and ripened in a test carried out at SSICA (Parma) under closely monitored and controlled conditions in a pilot-scale ripening chamber based on the "Air flow from bottom upward" technology. The work has been carried out within the R&D PON01_01409 "Safemeat" project. Among the various investigations, digital images were purposely acquired in a standardized way throughout the experimental test of sausage ripening. The graphical procedures here discussed involve a bit of image pre-processing, a digital image analysis work and some data post-processing. A pre-processing software introduces a black background around each photographed sausage. The open-source ImageJ software is used for recognizing and measuring the gut area covered by molds as a whole, distinguishing each individual mold colony, measuring its surface area and counting the overall number of colonies. Further data post- processing provides results in terms of percent surface covered by molds, number of mold colonies per unit gut surface and size distribution of colonies as a function of their individual area. Microbiological analyses confirmed that the fungal population established on the salami casing immediately after the surface inoculum was exactly corresponding to the mold starters. The developed methodology and the encouraging results obtained so far promise to be a rather simple and cheap way to control the onset and progress of the fungal colonization in industrial ripening chambers.