Volatilomics analysis reveals marker compounds for assessing chicken freshness and detecting frozen-thawed Korean native chicken

This study investigated the impact of frozen storage on the volatile compound profile of Korean native chicken (KNC) breast and identified marker compounds for freshness assessment and detection of frozen-thawed meat. Fresh samples were analyzed 2 hours postmortem, while frozen-thawed samples were stored at -18 °C for 7 days, thawed at 4 °C for 16 hours, and analyzed for volatiles using HS-SPME-GC-MS. The analysis identified 38 volatile compounds, with aldehydes, being the most prevalent. Freezing significantly reduced pH, increased TBARS values, and altered the relative abundance of several aldehydes and alcohols (P < 0.05). Notably, frozen-thawed samples showed increased levels of aldehydes with 6-10 carbon atoms and compounds such as 1-octen-3-ol, 1-octanol, and 2-ethyl-1-hexanol, indicating lipid oxidation. PCA, and PLS-DA, effectively differentiated between fresh and frozen-thawed samples, with the first two components explaining 50 % of the total variance. The top five discriminatory compounds identified by the Variable Importance in Projection (VIP) scores of over >1.2 included 2-heptanal, 4-pentylbenzaldehyde, (E)-2-octenal, 1-dodecanol, and 2-ethyl-1-hexanol. Among these, 4-pentylbenzaldehyde was positively associated with fresh chicken, while the others were linked to frozen-thawed samples. These findings indicate that freezing- and thawing-induced changes in volatile compounds can serve as reliable markers of freshness. Overall, this analytical approach shows strong potential for quality control and for distinguishing fresh from frozen-thawed KNC.