Storage Temperature Effect on Shelf Life Characteristics of Roasted Coffee Beans Packaged in Metalized Bag With a Pressure Releasing Valve

ABSTRACT The effect of storage temperature on moderately dark roasted coffee beans packaged in Al‐metallized bags was investigated focusing on the package atmospheric change and the product quality deterioration. Al‐vacuum metallized bag packages of 100 g product attached with a pressure‐releasing valve were stored at 15°C, 25°C, 35°C, and 45°C, with measurements in changes of package gas composition, package volume, and product quality attributes. Package atmospheric and volumetric change behavior was examined in relation to the product's carbon dioxide production measured in a separate experiment. The CO 2 production was characterized using the Weibull function form, which effectively quantified the influence of temperature: higher storage temperatures resulted in increased and faster CO 2 production with activation energy of 17–18 kJ/mol as described by the Arrhenius dependence. The headspace, originally containing ambient air, transitioned to and maintained the high CO 2 partial pressures mostly exceeding 0.7 atm, alongside reduced O 2 and N 2 partial pressures of 0.01–0.02 and 0.07–0.11 atm, respectively, due to flushing by CO 2 gas released from the coffee beans. This initial shift in gas concentration was more pronounced at higher temperatures. While temperature exhibited no significant effect on pH and titratable acidity changes of the product except at the later stage at 45°C, oxidation measured in peroxide value increase was found to be a primary quality degradation factor. This oxidation process showed clear dependence on temperature, following the Arrhenius equation with an activation energy of 42.5 kJ/mol, suggesting its suitability as a model for accelerated shelf life testing.