Specialty green coffee is changing the way we look at the various aspects of coffee and is challenging the way we measure quality. Historically, the moisture content of a coffee has prevailed as the common measurement used to measure water content within the industry. Moisture content, the percentage of water in the system of a product, has been used as a key factor in analysing a coffee’s quality and therefore how it will roast and taste. More recently, the coffee industry is looking into other measurements in order to gain a deeper understanding of the quality of green coffee beans, from pre shipment samples all the way to the arrival of the coffee. Not only does this provide an increased level of knowledge on the composition of the coffee but supports buying decisions and buying confidence.
Water activity measures the water vapor pressure of a product, such as a green coffee bean, in comparison to the water vapor pressure of pure water under the same condition. What this shows is the amount of water in a product that is unbound, indicating the amount of water available to microorganisms for growth. Thus, incredibly important when understanding the potential of spoilage, pathogenic bacteria, and microbial growth of a product. For coffee, water activity becomes an important factor for various outcomes, such as sensory qualities and shelf life.
So, what is happening to the green beans with higher water activity? High water activity tends to be associated with lipid oxidation, reaction between fatty acids and oxygen. Lipid oxidation can promote negative sensory characteristics of the coffee, such as wet cardboard. Additionally, lipid oxidation is not reversable, therefore, throughout the stages of the supply chain, water activity should be controlled.
Studies have shown that green beans with a higher water activity reading have deteriorated in quality more quickly over the supply chain timeline in comparison to green beans with a lower water activity reading, across multiple origins. Similarly, studies have demonstrated that a pre shipment sample of green coffee with a water activity above 0.610 had a score of 90+, by the time that the coffee arrived and was in store for 3 months, the coffee had already dropped to an average score of 81, indicating a huge impact on sensory quality of the coffee.
This year at LCM, we have invested in a water activity meter to further our quality assessments of our coffee. In addition to measuring water activity, we utilise the best practice for moisture content ensuring the purchasing of coffee with low percentage moisture content. Additionally, we ensure our coffee is stored in climate-controlled conditions, all contributing to the protection of the sensory qualities of the coffee.
We are so excited to have this added quality capability and will continue to producethe most up to date quality information to be able to provide confidence in our customer’s purchasing decision. While there are still potential moisture impacting factors from pre-shipment samples to the arrival of the coffee, the added data point provides us more information than we have had before. For more information, please contact us here.