A national survey of American millennial coffee drinkers conducted by Roasting Plant Coffee just ahead of National Coffee Day (Sept. 29) and International Coffee Day (Oct. 1) uncovered big gaps in knowledge about what makes coffee fresh, how long to keep it and where to store it.

Roasting Plant’s online survey of 1,000 coffee-drinking millennial Americans, conducted last month, uncovered surprising misunderstandings and behaviors:

•    While 70% of millennial coffee drinkers said they know what makes coffee fresh, only 24% properly identified the biggest factor in freshness: how soon after roasting it’s prepared.

•    Roasting Plant found that 62% of make-at-home coffee lovers store their coffee for three weeks or more, while only 12% keep it for a week or less.

•    Studies by the Specialty Coffee Association and The Zurich University of Applied Science found that coffee’s taste and aromas degrade by as much as 70% within 10 days of roasting.

•    40% of those surveyed who make coffee at home store it in the freezer, despite the well-chronicled negative effects freezing and moisture have on coffee's molecular makeup – and by extension, its flavor.

•    75% of coffee drinkers purchase ground coffee to make at home, the survey found. While that may be convenient, grinding rapidly accelerates coffee’s degradation due to CO2 loss (“off-gassing”).

•    The SCA and Zurich University of Applied Sciences found that ground coffee off-gases almost completely in matter of days or even hours. Nearly 70% of the CO2 is released within one day of grinding, causing coffee’s flavor and aroma compounds to rapidly degrade within days.

•    Coffee drinkers love their gear. Those surveyed have three coffee-preparation devices at home, with drip machines (48%), pod machines (46%) and grinders (41%) comprising the Top 3.

The survey was conducted for Roasting Plant Coffee by Prodege, which collected data via an online survey from a random sampling of 1,000 U.S. millennials (age 26-41) who visited a specialty coffee shop or drank specialty coffee during August 2022. Scientific research was cited from The Specialty Coffee Association and Zurich University of Applied Sciences, Coffee Freshness Handbook 2018.