Why your Coffee is Sour/Bitter! (and how to fix it)

Summary

This video explores the science of coffee extraction, focusing on the effects of under- and over-extraction on flavor. The speaker demonstrates how adjusting brewing parameters like dose, grind size, and extraction time can balance acidity and bitterness. Through taste exercises, viewers learn to recognize these changes in both espresso and pour-over methods. The video emphasizes the importance of experimenting with extraction ratios and understanding the role of volatile compounds in coffee flavor. Aimed at improving home brewing techniques, the content is both informative and practical, offering viewers the tools to enhance their coffee experience.

Takeaways

• 😀 Understanding coffee extraction is key to balancing flavors like acidity and bitterness.
• 😀 Early extraction often leads to high acidity and sourness in espresso.
• 😀 Over-extraction can cause bitterness and drying sensations in coffee.
• 😀 Underextracting espresso, especially in dark roast, can result in salty and biting flavors.
• 😀 Adjusting the ratio of coffee grounds to water can significantly alter the flavor balance in espresso.
• 😀 Adding more coffee grounds or reducing output can help dial in the extraction for better flavor.
• 😀 Even in dark roasted coffee, there is still a significant amount of acidity that can cause sourness if underextracted.
• 😀 Grinders producing a lot of fines can increase bitterness and result in uneven extractions.
• 😀 Balancing coffee concentration by adjusting volumes can help dilute excessive bitterness or sourness.
• 😀 Different coffees have inherent acidity, which can still be perceived even at higher extraction percentages.
• 😀 Coffee brewing adjustments are subjective, and understanding the science helps achieve personalized taste preferences.

Q & A

What is the primary purpose of splitting the espresso into two separate cups during extraction?

The purpose of splitting the espresso into two cups is to isolate the early and late parts of the extraction, which helps in identifying the different flavor profiles and understanding the balance of acidity and bitterness in the coffee.

Why is underextraction in espresso often associated with sourness?

Underextraction occurs when not enough of the coffee's compounds are extracted, particularly the acidic ones, which leads to an overly sour taste. This happens because the early part of the extraction, which contains volatile organic compounds, is more concentrated.

How does a dark roast coffee compare to a lighter roast in terms of acidity?

Dark roast coffee tends to have less perceived acidity compared to a lighter roast. During roasting, the levels of acids like citric and malic acid decrease, though acetic acid can still contribute some acidity, even in darker roasts.

What are fines in coffee brewing, and how do they affect the taste of the espresso?

Fines are tiny coffee grounds that can make it through the filter during extraction. They contribute to bitterness and a dry, coating mouthfeel in the coffee. Excess fines can lead to an uneven extraction, resulting in both sourness and bitterness.

Why does the early part of an espresso shot taste more concentrated and intense?

The early part of an espresso shot is more concentrated because the water initially extracts more of the highly volatile compounds, including intense acids and bitter substances. This leads to a strong, often sour or acidic taste.

What can be done to reduce the bitterness and sourness when tasting the early extraction?

To reduce bitterness and sourness, you can dilute the early extraction by adding a later, less concentrated portion of the shot or adjust the extraction by adding a bit more coffee or tweaking the grind size and brewing time to optimize balance.

How does the amount of coffee used in the basket affect the extraction and final flavor?

The amount of coffee in the basket influences the concentration of compounds extracted during brewing. More coffee leads to a higher concentration of flavors, and less coffee may lead to underextraction, affecting the overall flavor balance.

What is the significance of the 18-19% extraction yield in espresso brewing?

An 18-19% extraction yield is typically considered ideal for espresso because it represents the optimal balance between extracting flavorful compounds while avoiding over-extraction, which can lead to bitterness and undesirable flavors.

How can slight adjustments, like adding 5 extra grams of coffee, influence the flavor of the espresso?

Adding 5 extra grams of coffee can significantly impact the extraction by increasing the amount of soluble compounds that are extracted, helping to balance sourness or bitterness and create a more harmonious cup of coffee.

What role do volatile organic compounds (VOCs) play in coffee flavor, and how does their concentration change during extraction?

Volatile organic compounds (VOCs) are responsible for much of the aroma and flavor in coffee. Their concentration is highest in the early stages of extraction, and as extraction progresses, the concentration of these compounds decreases, which affects the flavor profile of the final brew.