Changes of Sensory Quality Characteristics of Coffee During Storage

Coffee is one of the world´s most popular beverages, but stored quite long before consumption. How long can roasted coffee beans be stored, without reducing the typical flavour of coffee beverages which is mainly responsible for the consumer’s enjoyment? In Austria most coffee packages have a best-before date between 12 and 24 months, but it is not regulated by law. Therefore, it was needed to evaluate sensory changes of coffee beverages prepared of stored coffee beans.
Green coffee (Arabica from Ethiopia and Robusta from Vietnam) was freshly roasted, packed under vacuum conditions and stored in the dark at ambient temperature over a period of 18 months. For the preparation of the coffee beverages the paper filter method was used.
In the Quantitative Descriptive Analysis (QDA) 10 trained individuals evaluated the intensity of 32 coffee attributes after roasting, 9 and 18-month of storage.
The results of QDA showed that freshly roasted, and the stored coffees had significant differences in the intensity of all evaluated sensory attributes in both investigated coffee cultivars. Already after 9-months the positive associated flavour attributes such as brew-like, roasted and fruity or the sweet taste decreased in their intensity. In contrast, the negative associated flavour attributes like burnt, woody, earthy, hay, bitter taste and aftertaste or astringency and staleness increased significantly. After 18 months of storage, the rancid odour and flavour were even considerably perceivable.
The conducted sensory evaluation demonstrated adverse effects on the quality of coffee beverages straight after 9-months storage of roasted coffee beans. After 18 months, the intensity of attributes which indicate oxidation processes increased. Consequently, we can conclude that sensory changes are likely during storage of roasted and vacuum-packed coffee beans. Therefore we suggest testing the duration of storage of roasted coffee beans by the producers and recommend declaring the best-before date on the package.