Microbiological, Physicochemical, and Functional Quality of Crossbred Native Chicken (Khao Dok Khae) During Extended Frozen Storage

Crossbred native chicken (Khao Dok Khae) holds commercial significance in Southern Thailand, yet empirical data on its post-harvest quality under extended frozen storage remain limited. This study evaluated the microbiological quality of Khao Dok Khae over 480 days at −18 ± 2 °C, with commercial broiler chicken included as a reference for physicochemical and cooking loss comparisons. A total of 40 chickens (20 Khao Dok Khae, 20 broilers; approximately equal sex ratio in each group, allocated without stratification by sex as sex was not a primary variable) were slaughtered at 16 weeks. Broiler chickens were maintained to 16 weeks to match the slaughter age of Khao Dok Khae, enabling direct comparison of breed-specific quality traits at equivalent rearing duration rather than at commercial processing age. It is acknowledged that the sample sizes used (n = 2 microbiological; n = 3 physicochemical and cooking loss; n = 1 texture) are limited; the results should be interpreted as preliminary breed-characterisation data requiring confirmation with larger samples in future studies. No experimental randomisation between breed groups was performed; assessors were not blinded to breed identity during physicochemical measurements, which is acknowledged as a potential source of measurement bias. Microbiological quality was monitored at seven storage time points (Day 0, 90, 150, 210, 270, 360, 480), while physicochemical, colourimetric, and cooking loss properties were characterised at a single representative time point within the storage period. Total viable counts (TVC) increased from 3.40 × 102 to 1.61 × 103 CFU g−1; yeast and mould remained below 1.0 × 103 CFU g−1 throughout, all within TIS 590-2528 and ICMSF limits. Log-linear regression confirmed significant but suppressed microbial growth (TVC: R2 = 0.93, p < 0.001; yeast and mould: R2 = 0.92, p < 0.001). The pH values (5.73–6.13 fresh) indicated normal postmortem conditions with no PSE or DFD anomalies. Native thigh showed significantly higher redness (a* = 7.75 vs. 6.61; p < 0.05), attributable to oxidative muscle fibre development. Statistical analysis demonstrated that meat cut, not breed, was the primary determinant of cooking loss (p < 0.001). These findings indicate that based on the microbiological and physicochemical parameters assessed, Khao Dok Khae maintained acceptable quality over 480 days of frozen storage under the evaluated cold-chain conditions.