Kinetics and mechanism of carotenoid degradation in pumpkin powder: effect of storage temperature and packaging atmosphere

Carotenoids are highly susceptible to oxidative and thermal degradation, which compromises the nutritional and functional quality of plant-based food powders. This study aimed to establish the kinetic parameters governing carotenoid degradation in enzyme-hydrolyzed pumpkin powder under varying storage temperatures (4, 20, and 30 °C) and gas atmospheres (vacuum, nitrogen, carbon dioxide, and ambient air). Carotenoid content was monitored spectrophotometrically over 12 months, and degradation kinetics were modeled using first-order reaction kinetics and the Arrhenius equation. The degradation process followed first-order kinetics in all conditions (R 2 > 0.998). Oxygen presence dramatically accelerated carotenoid loss: degradation rate constants in air were 2.4–5.1 times higher than in inert or vacuum environments. Activation energies (Eₐ) were significantly higher in oxygen-free systems (48.8–59.4 kJ/mol) compared to air (41.4 kJ/mol), indicating a shift from oxidation-driven to thermally driven degradation mechanisms. Based on the kinetic models, shelf life (defined as 20 % carotenoid loss) was predicted across temperature – atmosphere combinations. For cold-chain storage (0...4 °C), nitrogen or CO 2 packaging provided the longest shelf life (~20 months), whereas vacuum packaging proved superior under temperature abuse (e.g., 30 °C), extending shelf life to ~13 months versus 2.5–7.5 months in air. The practical significance of this work lies in providing a scientific basis for packaging selection: vacuum packaging is recommended for long-term storage, especially with the risk of temperature fluctuations, while packaging under a nitrogen or carbon dioxide atmosphere is optimal for guaranteed cold chain storage.