Comparative Survey on Predictive Impediometric Models for Microbial Load in Vanilla and Cocoa Ice-Creams Produced with Traditional and Industrial Methods

Measuring total microbial count of ice-cream with conventional pour plate count method and comparing the results with standard limits is one of the routine tests in ice-cream manufacturer factories. Achieving the results of total microbial count in minimum time is really important for confidence from the hygienic quality of products. So impedance-splitting method as a new technique for this purpose was considered in order to receiving the results in less time and as soon as possible. The main purpose of this study was to evaluate the correlation between impedance detection time (IDT in hrs.) and total microbial population (log 10 N) of industrial and traditional ice-cream in order to design the predictive microbial model according to impedance technique. During 6 months, 120 samples (60 samples for industrial and 60 samples for traditional ice-cream) were collected from different areas of Ahvaz. Half of samples in both industrial and traditional ice-creams were Vanilla and the other half were cocoa. Samples examined under sterile conditions. The total microbial count by pour plate technique and impedance splitting method were carried out based on the recommendations of Iran's Standard Institute and Industrial Investigation. Then the calibration curves of 2 methods and their equations were obtained by using Excel software. The calibration curves of methods were elaborated for total microbial count and impedance detection time, demonstrating a good correlation between the two methods in industrial ice-cream 96.55% and 95.31% for Vanilla or plain and cocoa ice-creams respectively). According to the calibration curves, the correlation between two methods was 89.07% and 87.37% for plain and cocoa traditional ice-creams respectively. In general the correlation between two methods was 94.61% for industrial and 87.92% for traditional ice-cream. Therefore, impedance measurement which is a more rapid, automated and less laborious method than conventional total microbial count technique could be used like some developed countries as an alternative method for the rapid measuring the total microbial loads in foods instead of conventional methods.