Identification and Quantification of Volatile Chemical Spoilage Indexes Associated with Bacterial Growth Dynamics in Aerobically Stored Chicken

Abstract

Volatile organic compounds (VOCs) as chemical spoilage indexes (CSIs) of raw chicken breast stored aerobically at 4, 10, and 21 degrees C were identified and quantified using solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS). The growth dynamics of total viable count (TVC), psychrotrophs, Pseudomonas spp., lactic acid bacteria (LAB), Brochothrix thermosphacta and H2S producing bacteria were characterized based on maximum growth rates (mu(max)), maximal microbial concentration (N-max) and at the moment of microbial shelf life (S-values), calculated from Gompertz-fitted growth curves. Pseudomonas spp. was predominant species, while B. thermosphacta was characterized by the highest mu(max). The microbiological and sensory shelf lives were estimated based on TVC, Pseudomonas spp., and B. thermosphacta counts and sensory evaluation, respectively. Among 27 VOCs identified by GC-MS in spoiled chicken samples, ethanol (EtOH), 1-butanol-3-methyl (1But-3M), and acetic acid (C-2) achieved the highest Pearson's correlation coefficients of 0.66, 0.61, and 0.59, respectively, with TVC, regardless of storage temperature. Partial least squares (PLS) regression revealed that the synthesis of 1But-3M and C-2 was most likely induced by the metabolic activity of B. thermosphacta and LAB, while EtOH was attributed to Pseudomonas spp. The increase in concentration of selected volatile spoilage markers (EtOH, 1But-3M, and C2) in the headspace over spoiled chicken breast was found to be statistically significant (P < 0.05) with TVC growth. These findings highlight the possibility of analyzing the combination of 3 selected spoilage markers: EtOH, 1But-3M, and C-2 as rapid evaluation for poultry quality testing using SPME-GC-MS.