Effect of the addition of starter cultures to ground meat for hamburger preparation

The aim of this work was to study the effect of a selected lactic acid bacteria formulation on the microbiological characteristics and colour of beef hamburgers stored at different temperatures. All hamburgers were evaluated on day-0, day-1, day-3, and day-5 for the following microbiological parameters (Staphylococcus spp., enterococci, Lactococcus spp., Lactobacillus spp., total mesophilic aerobes, Pseudomonas spp., total coliforms) according to standard methods and for colorimetric measurements performed with Colorimeter - Digital Color Picker for iOS 10, under a 6500K light, with the CIELab system. All data (geometric mean for microbiological data) were elaborated with GraphPad InStat, 3.0b and GraphPad Prism 6.0d for Mac OS X. Two-way analysis of variance (ANOVA) followed by the Tukey's multiple comparisons test was performed. The analysis of the colour proved that the addition of Lactic Acid Bacteria (LAB) does not affect the natural colour of ground meat, avoiding the risk of hiding the spoilage or fastening it. The addition of the starter has preserved the colour stability throughout the preservation period, with the same behaviour both in the hamburgers stored at 4 degrees C and in those at 10 degrees C after thermal abuse or not. In conclusion, the application of the proposed LAB formulation maintains hamburgers quality standards and can be a potential tool to increase their shelf-life.