Is Coffee Bean Oil Good or Bad?
【Coffee Trivia】Is Coffee Bean Oil Good or Bad?
2023-09-21Coffee Trivia
Many coffee articles and books claim that "coffee bean oil means the beans are not fresh enough." But let me tell you, this statement is not entirely accurate and has led to misconceptions about coffee. People often believe that the oil on coffee beans is a sign of prolonged storage, overlooking more critical factors. In reality, the amount of oil on coffee beans is not solely determined by their age; it is primarily influenced by the degree of roasting and the roasting method!
Evolution of Coffee Roasting
In the early days of coffee, there was no coffee "roasting" process. People directly chewed on coffee fruits, and later progressed to boiling them to make "medicinal fruit juice." It was only with the advancement of industrial technology (or some say accidentally throwing coffee beans into the fire by shepherds) that the current method of "roasting" coffee beans was introduced. Coffee roasting not only extracts caffeine but also allows for a refined flavor experience after brewing, captivating many coffee enthusiasts.
With the prevalence of coffee roasting, the possibility of coffee beans "exuding oil" also emerged. To help you better understand, let's first understand the different roasting methods, which can be roughly divided into three categories: direct fire, hot air, and semi-hot air.
1. Direct Fire Roasting: This method uses a drum coffee roaster with small holes, allowing the fire to directly contact the coffee beans. If the roasting is controlled properly, the coffee beans' aroma will be excellent, but it also makes controlling the fire more challenging.
2. Hot Air Roasting: This method mainly uses high-temperature and powerful hot air to pass through the coffee roasting machine, allowing the beans to be thoroughly blown, providing optimal heat transfer, shorter roasting time, and a crisp and bright coffee flavor.
3. Semi-Hot Air Roasting: Also known as semi-direct fire roasting, there are no holes on the surface where the drum and the flame touch, but the innermost part of the drum has small holes that guide hot air into the roasting chamber, assisting the metal of the drum to conduct heat evenly for the beans. Adjusting the fire is more convenient than direct fire roasting, and the flavor is characterized by a rich and sweet aftertaste.
Key Factor: Roasting Degree
During roasting, coffee beans gradually expand and crack, causing the oils inside to surface and create an oily appearance on the beans. The deeper the roasting degree, the more pronounced the oil exudes!
Therefore, lightly roasted coffee beans hardly exude oil, so do not solely judge the freshness of coffee beans based on the oiliness. For medium to dark roasted coffee beans, due to the longer roasting time, the beans expand significantly, making it easier for carbon dioxide and oils to be released from the beans, resulting in the beans appearing oily even after a short period of storage.