Friday, 5th May, 2023
Our team at Specialty Batch Coffee recently conducted a relatively detailed comparative study in our training lab. The objective was to evaluate the sensory attributes in terms of quality when brewing coffee immediately after roasting versus brewing a rested coffee
Hypothesis: Brewing coffee immediately after roasting may result in a more intense aroma, but may compromise the overall flavor balance and other sensory attributes compared to coffee that has rested.
Methodology:
- Sample selection and preparation: Two batches of the same single-origin, 95 agtron roast coffee were prepared. Batch ‘A’ was brewed immediately after roasting, while batch ‘B’ were immediately packed in our bags with one-way valve after roasting and allowed to rest for 4 days before brewing.
- Brewing methods: Three popular brewing techniques were employed to assess the impact of resting on various coffee extraction methods. The selected methods were pour-over, French press, and espresso.
- Sensory evaluation panel: A panel of 8 trained coffee tasters evaluated each sample using a standardised sensory analysis protocol based on the Specialty Coffee Association (SCA) cupping form. The tasters were blinded to the treatments and given randomised samples for evaluation.
- Sensory attributes: The sensory evaluation focused on six attributes: aroma, flavor, acidity, body, aftertaste, and overall quality. Each attribute was rated on a 1-10 scale, with 10 being the highest quality.
- Data analysis: The mean scores for each attribute were calculated, and a paired T-test was performed to determine any statistically significant differences between the immediately brewed coffee and rested coffee.
Test Results:
| Sample | Brew Method | Aroma | Flavor | Acidity | Body | Aftertaste | Overall Quality |
|---|---|---|---|---|---|---|---|
| A-1 | Pour-over | 7.5 | 6.0 | 5.5 | 6.0 | 5.5 | 6.1 |
| A-2 | French press | 7.8 | 6.2 | 5.6 | 6.3 | 5.7 | 6.3 |
| A-3 | Espresso | 8.0 | 6.5 | 5.8 | 6.5 | 5.8 | 6.5 |
| B-1 | Pour-over | 7.0 | 7.2 | 6.5 | 6.8 | 6.7 | 7.0 |
| B-2 | French press | 7.2 | 7.5 | 6.8 | 7.0 | 6.9 | 7.2 |
| B-3 | Espresso | 7.3 | 7.2 | 7.2 | 6.9 | 7.1 | 7.1 |
Note: Ratings are based on a 1-10 scale, with 10 being the highest quality. Batch A represents coffee brewed immediately after roasting, while batch B represents coffee that has rested for 4 days. A strict protocol was followed to ensure all coffees were fully-saturated within 30 seconds of grinding.
Results: Brewing coffee immediately after roasting (batch A) resulted in a more intense aroma compared to rested coffee (batch B). However, the rested coffee samples received higher scores for flavor, acidity, body, aftertaste, and overall quality, indicating a more balanced and enjoyable sensory experience. The paired T-test revealed statistically significant differences (p < 0.08) between the two groups for all attributes except aroma.
Conclusions: This study suggests that brewing coffee immediately after roasting may enhance the aroma but may compromise other sensory attributes, such as flavour balance, acidity, body and aftertaste, as well as overall quality. Resting coffee for 4 days before brewing appears to yield a more balanced and well-rounded sensory profile, as evidenced by the higher ratings. While the aroma intensity may be slightly reduced in rested coffee, the overall sensory experience is improved, suggesting that the benefits of resting coffee outweigh the drawbacks. Therefore, the hypothesis is supported by the results of this study.
Posted by Ryan Godinho
Categories: Coffee Quality