A Comparative Study Between Detection Methods for Spoilage Microorganisms in Fruit Juice

Abstract: The main concerns of food spoilage in fruit juices are the off-flavours and off-odours caused by microorganisms. In order to ensure high quality products, these microorganisms must therefore be eliminated or below a certain limit. Trials using pear concentrate, a ready-to-drink pear drink and a carbonated pear drink, were performed in order to compare two detection methods for three different groups of microorganisms: Total Count, Yeast & Moulds and Alicyclobacillus spp. The two methods compared were the standardised IFU methods for these three groups as well as the currently used In House (IH) method for the Company at whose disposal this study was conducted. The objective of the study was to investigate if a switch from the IH method to the IFU method could be carried out by the Company. In order to do this, the results between the methods need to be comparable and of similar sensitivity. The obtained results showed a tendency for similarity between the IFU and IH method for Total Count as well as Yeasts & Moulds. Regarding Alicyclobacillus spp., it seemed that the sensitivity of the method was higher for IH than IFU. The difference was in part suspected to be due to the pre-incubation step included in IH, not found in IFU. It is recommended that a pre-incubation period is added to the IFU method as allowed by IFU and that more trials are performed.