Background
We will be constructing a siphon extraction process for coffee, which utilizes pressure differences and vacuums for extractions. Below are videos and questions that provide information regarding the coffee extraction process and relates chemical processes, the siphon extraction process, and related gas laws. Additionally, questions regarding how pH and extracted solids relate to quality are addressed.
Tutorials
2. Inside a Mr. Coffee--
This document reflects our findings when taking apart a Mr. Coffee Machine. It provided our group with insight regarding the efficiency of the heating mechanisms within standard coffee brewing devices. experiment 1 findings
This document reflects our findings when taking apart a Mr. Coffee Machine. It provided our group with insight regarding the efficiency of the heating mechanisms within standard coffee brewing devices. experiment 1 findings
3. pH vs. Time--
This document reflects our findings when observing the change in pH over time after being brewed using a Mr.Coffee Machine. Additionally, it holds notes regarding the pH differences in light-roasted compared to dark-roasted coffee. These experiments provided the reasoning for our optimization goal of producing a cup of coffee at low acidity. experiment 2 findings
4. TDS vs. Brew Time
This document reflects our findings when observing the change in total dissolved solids concentration over brew time, which helped us estimate an extraction time for our brew.
experiment 3 findings
This document reflects our findings when observing the change in pH over time after being brewed using a Mr.Coffee Machine. Additionally, it holds notes regarding the pH differences in light-roasted compared to dark-roasted coffee. These experiments provided the reasoning for our optimization goal of producing a cup of coffee at low acidity. experiment 2 findings
4. TDS vs. Brew Time
This document reflects our findings when observing the change in total dissolved solids concentration over brew time, which helped us estimate an extraction time for our brew.
experiment 3 findings
Frequently Asked Questions
1. What quantifies a good cup of coffee?
The quality of coffee is a subjective topic, which is mostly dependent on taste. Because we are not permitted to taste any of the coffee in the lab or may have different opinions regarding the taste, we have decided to use acidity as a measurement for the extraction quality. In our findings, a lower acidity relates to a better tasting cup of coffee, bringing out fruity tastes.
Source: low acidity coffee
2. What is extracted in coffee?
Fats and Organic Acids will be extracted first from the water, followed by sugars and plant fibers. Many factors, such as the grind size and the roast, affect the solubility of the total dissolved solids (TDS) in water. For example, roasting coffee beans to the first crack allows for the breakdown of complex sugars, allowing for an easier dissolution of sugars. This correspondence is evident from the sweetness of darker roasts. Additionally, a finer grind size allows for an easier diffusion through water molecules, allowing for a faster extraction rate.
Only about 30% of the solids in coffee can be extracted (the remaining 70% is undissolved cellulose). However, this does not result in an optimal taste (the additional acids can make the coffee bitter). Our goal is to have an extraction yield of 20%.
dissolved solids
3. What is the difference between extraction yield and total dissolved solids?
As aforementioned, in the coffee extraction process, only 30% of the solids in coffee can be extracted. The extraction yield refers to the percent of the solids that had been extracted from the original brew. For instance, if 30 grams of coffee were placed in a brewer and 6 grams of coffee solids were in the brew, then 20% of the solids had been extracted. Because the solids of coffee diffuse in water during the extraction process, the mass of the dissolved solids is not easily determined. The percentage amount of TDS (total dissolved solids) is used to calculate the extraction yield by the following equation:
Extraction Yield % = (Mass of Brewed Coffee)*(TDS)/ (Initial mass of Coffee)
Source: TDS vs. Extraction Yield
The quality of coffee is a subjective topic, which is mostly dependent on taste. Because we are not permitted to taste any of the coffee in the lab or may have different opinions regarding the taste, we have decided to use acidity as a measurement for the extraction quality. In our findings, a lower acidity relates to a better tasting cup of coffee, bringing out fruity tastes.
Source: low acidity coffee
2. What is extracted in coffee?
Fats and Organic Acids will be extracted first from the water, followed by sugars and plant fibers. Many factors, such as the grind size and the roast, affect the solubility of the total dissolved solids (TDS) in water. For example, roasting coffee beans to the first crack allows for the breakdown of complex sugars, allowing for an easier dissolution of sugars. This correspondence is evident from the sweetness of darker roasts. Additionally, a finer grind size allows for an easier diffusion through water molecules, allowing for a faster extraction rate.Only about 30% of the solids in coffee can be extracted (the remaining 70% is undissolved cellulose). However, this does not result in an optimal taste (the additional acids can make the coffee bitter). Our goal is to have an extraction yield of 20%.
dissolved solids
3. What is the difference between extraction yield and total dissolved solids?
As aforementioned, in the coffee extraction process, only 30% of the solids in coffee can be extracted. The extraction yield refers to the percent of the solids that had been extracted from the original brew. For instance, if 30 grams of coffee were placed in a brewer and 6 grams of coffee solids were in the brew, then 20% of the solids had been extracted. Because the solids of coffee diffuse in water during the extraction process, the mass of the dissolved solids is not easily determined. The percentage amount of TDS (total dissolved solids) is used to calculate the extraction yield by the following equation:
Extraction Yield % = (Mass of Brewed Coffee)*(TDS)/ (Initial mass of Coffee)
Source: TDS vs. Extraction Yield