Analysis of quality loss in the roasted coffee bean storage and improvement based on Internet of Things (IoT)

The quality of coffee is of paramount importance, and this study focuses on analyzing the moisture content, pH, and CO2 degassing rate of roasted coffee beans to determine the effect of ambient storage on their quality. Ambient storage with fluctuating temperature condition was commonly found in coffee shops. During the study, ambient temperature fluctuated in the range from 26.5 to 32.5°C. The study revealed that the ambient storage temperature has no significant impact on the moisture content and pH of the roasted coffee beans during the eight-day-storage. However, a noticeable variation in the CO2 degassing rate was observed during the storage across this temperature range. When the storage’s temperature increased, the CO2 release was also increased from the beans during the first four days. The sensory evaluation with coffee experts further confirmed the detrimental effects of ambient temperature on coffee cup’s sensory properties which were perceived as freshness qualities for the consumers. Statistical analysis showed a high Pearson correlation coefficient of r =-0.914 between the cumulative CO2 degassing and the overall sensory score. This negative correlation suggests that as the cumulative CO2 degassing rapidly increases, the overall sensory score decreases. This can be attributed to the fast depletion of CO2 inside the coffee beans, leading to faster oxidation as well as decline in the desired sensory qualities and the overall quality of the coffee. Notably, a threshold ambient temperature of 30.7°C was identified, beyond which the rate of CO2 degassing has accelerated significantly high. The implementation of an IoT-based monitoring system was proposed in detecting the threshold temperature conditions that led to rapid CO2 degassing. When such temperature was approached, the system would promptly send alert notifications, enabling swift corrective actions to maintain the coffee's quality. This study underscores the importance of timely interventions to ensure the preservation of coffee quality throughout the storage process.

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