Detection of microbial contamination in fruit juices using non-invasive ultrasound

The aim of this work is to analyze the viability of using non-invasive ultrasonic methods to detect microbiological contamination in industrial fruit juices. Microbial growth in UHT fruit juices was monitored by an ultrasonic measuring system based on pulse transmission. The wave time of flight across different media was registered continuously during incubation. Three types of juices were used as substrate: apple juice, orange juice and peach&grape juice, and three different microorganisms were separately inoculated in these juices: bacteria (acidolactic mixture), yeasts (Saccharomyces cerevisiae) and molds (Aspergillus niger). It is shown that time of flight evolution is clearly affected by the growth of such microorganisms, these changes being dependent on the juice and the contaminant agent. These results support the viability of using ultrasonic measuring devices to assess the microbiological quality control in juices, decreasing detection times and reducing economical wastes when contaminations appear.