Microbiological characteristics of traditionally-produced salted eggs in Indonesia

Abstract

This study investigates the microbiological characteristics of salted eggs, a popular delicacy in Indonesia known for its distinct flavor and extended shelf life. The traditional method of producing salted eggs adopted in this study involved coating fresh duck eggs in a paste made from rice husk ash, salt and water for 30 days. Due to the involvement of microorganisms in the production of salted eggs, the process has been proposed to be categorized as a spontaneous fermentation. This research aims to analyze, identify and compare the microbial communities present in fresh eggs and salted eggs in order to understand their role in flavor development and preservation. Microbial analysis was conducted using colony counting methods and 16S rRNA Next Generation Sequencing using Illumina MiSeq Platform to identify bacterial communities. Results indicated a significant increase of halophilic and lactic acid bacteria in salted eggs' white and yolk compared to fresh eggs. Firmicutes and Proteobacteria appeared to be the two most dominant bacterial phyla in salted eggs. Major Proteobacteria genera in fresh eggs, such as Pseudomonas and Burkholderia, exhibited a significant decrease due to salting process. Firmicutes as the major bacterial phylum in salted eggs included lactic acid bacteria, such as Bacillus, Lactobacillus, Weissella, Pediococcus and Tetragenococcus, known for their salt tolerance and potential probiotic properties. As a whole, this study provides a thorough profiling of bacteria present in salted eggs for further insights, such as improving the safety and quality of salted eggs through microbial management.