Roasted and ground coffee was stored at constant O2partial pressure (0.5-21.3 kPa), aw(0.106-0.408) and temperature (4-35°C). Product acceptability was monitored by use of a modified Weibull Hazard sensory method where the end of shelf-life was the time at which 50% consumers found the product unacceptable. The effect of O2, awand temperature was studied from a kinetics standpoint. Oxygen increase from 0.5 to 21.3 kPa accelerated deterioration 20-fold. A water activity increase of 0.1 led to a 60% increase in deterioration suggesting non-enzymatic browning activity, while a temperature increase of 10°C rose the rate of deterioration about 15-23%. The activation for shelf life was ≅13 kJ/mole indicating diffusion within the glassy matrix is controlling deterioration.
- Weibull Hazard; shelf-life; coffee; staggered design