Planning Your Brewing & Inventory for the Best Tasting Cup

Did you know that you can optimize the timing of your coffee orders? Coffee’s resting period plays an important role in how it tastes and brews. Businesses can plan their inventory to break into new bags of coffee when it tastes best. Because compounds in roasted coffee like carbon dioxide (CO₂), oils, and volatile aromatics all play a major role in how coffee can taste over time, understanding how they interact and influence coffee’s flavor is a key step to determining the optimal resting time between roasting and brewing. 

It all starts with gas. CO₂, one of the byproducts of roasting coffee, escapes from the bean overtime. This phenomenon, known as “degassing”, can be both beneficial and harmful for quality. In general, coffee releases the most CO₂ during the first several hours after roasting, then tapers off over a few months. Because the chemical makeup and approach to roasting each coffee varies, so can the rate of degassing. Studies have shown that darker roasted coffees degas faster than lighter coffees. Brewing coffee that has not sufficiently degassed thwarts proper extraction due to the excess CO₂ pushing water away from the compounds, creating an unevenly extracted cup of coffee.

With accurate knowledge of the right resting time for even extraction and good tasting coffee, businesses can time their orders to ensure their inventory has a sufficient buffer between ordering and brewing coffee. For filter coffee, we at Speedwell recommend that darker coffees rest for at least 2 days after their marked roast date before brewing, and about 3-4 days for lighter coffees. We’ve noticed that certain light roasted coffees, particularly from Ethiopia, need extra resting time of up to 7 days before it tastes best. This is because the higher density of the bean leads to a slower, longer degassing period. 

Resting coffee intended for espresso use is a bit more intriguing, as CO₂ helps form the famous layer of crema. A recent study showed that the degassing of CO₂ correlates with decreased crema volume. The same study showed that the release of CO₂ and loss of crema volume both slowed after a week of resting. It is important to note that crema loss is not necessarily indicative of poor quality espresso, as is commonly thought. Too much crema, however, can be indicative of coffee that is too fresh and perhaps unevenly extracted. Baristas may notice that espresso that hasn’t been rested long enough is tricky to dial-in and constantly needs grind size adjustments. To prevent uneven espresso extraction and save time on drink prep, coffee intended for espresso use should rest for at least one week before brewing.

Coffee gasses can also play a role in the preservation of quality over time. CO₂ is an inert gas, meaning that it is not reactive with other chemical compounds. The degassing of CO₂ forms a barrier around the beans that protects them from oxygen, which would otherwise interact with elements of the coffee such as lipids and volatile compounds. The oxidation of lipids is the main cause of staleness in coffee. By the same token, the oxidation of certain volatile compounds that usually contribute to coffee's iconic aroma are greatly diminished after just 8 days of exposure to oxygen. To avoid disrupting the protective barrier of CO₂ and introducing oxygen, it is best to leave coffee in its original Speedwell packaging until you are ready to use it. Once you have broken into a bag of coffee, try to keep it sealed as tightly as possible so that it doesn’t stale.

The dynamic of oxidation and volatile compound loss is elevated in ground coffee.The rate of aroma loss is increased when coffee is ground, since the volatile compounds trapped within the structure of the bean are able to escape more easily. Studies show that this leads to complete aromatic loss after just a few hours if the grounds are not packaged in airtight bags. For this reason, we recommend ordering coffee in wholebean, opening, and grinding it only when you are ready to brew.

Taking all of this information into account, a good inventory plan could include having a week’s worth of whole bean coffee resting at all times. This essentially means being one week ahead of your orders. As long as coffee remains sealed and isn’t sitting for longer than a month, this range is ideal and will keep your coffee tasting consistently great. 

References, Sources, and Studies

• Anderson, Brent A., et al. “The diffusion kinetics of carbon dioxide in fresh roasted and ground coffee.” Journal of Food Engineering, vol. 59, no. 1, Aug. 2003, pp. 71–78, https://doi.org/10.1016/s0260-8774(02)00432-6. 
• Farah, Adriana, et al. “Post-Roasting Processing: Grinding, Packaging and Storage.” Coffee: Production, Quality and Chemistry, Royal Society of Chemistry, London, 2019, pp. 258–271. 
• Holscher, Wilhardi, and Hans Steinhart. “Investigation of roasted coffee freshness with an improved headspace technique.” Zeitschrift Für Lebensmittel-Untersuchung Und -Forschung, vol. 195, no. 1, July 1992, pp. 33–38, https://doi.org/10.1007/bf01197836. 
• Illy, Andrea, and Rinantonio Viani. Espresso Coffee: The Chemistry of Quality. Elsevier, 2005. 
• Kreuml, Michaela T., et al. “Changes in sensory quality characteristics of coffee during storage.” Food Science & Nutrition, vol. 1, no. 4, 4 May 2013, pp. 267–272, https://doi.org/10.1002/fsn3.35. 
• Smrke, Samo, et al. “Time-resolved gravimetric method to assess degassing of roasted coffee.” Journal of Agricultural and Food Chemistry, vol. 66, no. 21, 1 Nov. 2017, pp. 5293–5300, https://doi.org/10.1021/acs.jafc.7b03310. 
• Wang, Xiuju, et al. “Investigation of the factors that affect the volume and stability of Espresso Crema.” Food Research International, vol. 116, Feb. 2019, pp. 668–675, https://doi.org/10.1016/j.foodres.2018.08.095.