Storage stability of yolk pigmentation, lipid oxidative stability, and physicochemical quality in lutein-enriched eggs under refrigerated and ambient conditions.

Dietary lutein enrichment is widely used to improve yolk pigmentation and nutritional value, yet its contribution to egg quality stability during storage remains insufficiently defined. This study evaluated the effects of lutein enrichment on egg interior quality, yolk pigmentation, lutein retention, cooked-yolk texture, volatile profile, fatty acid composition, and lipid oxidation during refrigerated and ambient storage. Eggs were obtained from Jingfen No. 6 laying hens fed either a basal diet or the basal diet supplemented with marigold-derived lutein to provide 120 mg/kg supplemental active lutein. Control eggs (CE) and lutein-enriched eggs (LE) were stored at 4°C or 25°C for up to 30 d. Before storage, yolk lutein content was approximately threefold higher in LE than in CE (1452.53 vs. 480.13 μg/100 g edible portion; P < 0.001), confirming effective dietary deposition. Storage temperature and duration were the dominant determinants of conventional freshness deterioration, including increased weight loss, albumen thinning, Haugh unit decline, yolk index reduction, and yolk and albumen pH elevation (P < 0.05), whereas egg type exerted only minor and inconsistent effects on these indices. In contrast, LE maintained a persistent pigmentation advantage during storage, with higher yolk color score and greater a* and b* values than CE at both temperatures (P < 0.05), although lutein content was reduced after 30 d of storage, particularly at 25°C. Cooked-yolk texture was affected mainly by storage conditions, with limited egg-type effects. Electronic nose analysis showed progressive increases in W1W and W2W sensor responses during storage, particularly at 25°C, whereas this increase was attenuated in LE from the middle storage period onward. After 30 d at 25°C, LE had a higher relative proportion of total polyunsaturated fatty acid than CE (9.165 vs. 7.046 g/100 g; P < 0.01) and showed lower malondialdehyde-equivalent values across storage conditions (P < 0.001). These findings indicate that dietary lutein enrichment does not substantially delay conventional freshness loss but improves yolk pigmentation and lipid oxidative stability, particularly under ambient storage.