Identification of Microbial Flora in Dry Aged Beef to Evaluate the Rancidity during Dry Aging

Abstract

Dry aging creates a unique taste and flavor in beef; however, the process also causes rancidity, which is harmful to humans. During dry aging, the microbial flora in beef changes continuously; thus, this change can be used as an indicator of rancidity. The objective of this study was to analyze the correlation between microbial flora in beef and rancidity during dry aging. The round of beef (2.5–3 kg) was dry aged under 1.5 ± 1 °C and 82 ± 5% moisture for 17 weeks. The microflora in the dry aged beef was analyzed by pyrosequencing. The volatile basic nitrogen (VBN) and thiobarbituric acid reactive substance (TBARS) values were also measured. Primers were designed to detect and quantify bacteria using real-time polymerase chain reaction (RT-PCR). The VBN and TBARS values in the dry aged beef depreciated from week 11 of aging. The levels of Streptococcus spp., Pantoea spp., and Pseudomonas spp. significantly changed at around week 11. Quantitative RT-PCR showed that the levels of Pantoea spp. and Streptococcus spp. could be used to identify rancidity during dry aging. Thus, among the microbial flora in dry aged beef, Pantoea spp. and Streptococcus spp. can be used to determine the rancidity of dry aged beef.

Effects of Aging Methods and Periods on Quality Characteristics of Beef

“…Lactobacilli dominate under anaerobic conditions and Pseudomonas species dominate under aerobic conditions (Kim et al, 2021). In the present study, LAB counts showed no differences regardless of aging method or aging time except for wet aging.…”

“…Microorganisms such as bacteria, yeasts, and molds can grow both on surface and inside of beef during long-term aging. They can metabolize ingredients of beef and produce various metabolites, resulting in unique flavors of beef ( Kim et al, 2021 ). On the other hand, they can also cause lipid peroxidation and off-flavor ( Kim et al, 2021 ).…”

“…They can metabolize ingredients of beef and produce various metabolites, resulting in unique flavors of beef ( Kim et al, 2021 ). On the other hand, they can also cause lipid peroxidation and off-flavor ( Kim et al, 2021 ). Numerous microbes can colonize on the surface of dry aged beef (crust).…”

“…Pseudomonas spp. is one of the main spoilage bacteria, resulting in slime formation and off-flavor generation by metabolizing glucose, lactate, and amino acids (Kim et al, 2021).…”

Introduction to Special Issue: Study of Microbiological Safety in the Food Chain

“…The safety and quality characteristics of food can also be predicted by evaluating bacterial composition and growth during processing or storage. An example of this is the study by Kim et al [7], in which metagenomic tools were used to correlate rancidity and microflora in dry-aged beef. Using analysis and quantification of microflora by qRT-PCR, the authors demonstrated that increases in the number of Pantoea spp.…”