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Château d’Yquem: Sweet Wine Sugar and Acidity
A producer of sweet wines from botrytized grapes located in Sauternes, Bordeaux. They blend Sémillon and Sauvignon Blanc and publish annual data on harvests and components.
Introduce the 2023 d’Yquem by providing its grape varieties, residual sugar, and acid stats, and give one example of something that cannot be determined from the numbers alone.
Questions for this course
Can you explain the perceived sweetness when tasting a wine only from the number showing its high residual sugar?
Before you start reading, briefly jot down your thoughts. You will rephrase them at the end.
To applied practice using the material ↓
To explanation task notes ↓Château d’Yquem / Learn from the producer
France / Bordeaux / Sauternes
Other names & notations: Château d’Yquem / シャトー・ディケム / Chateau dYquem
Update date: 2026-09-24
Harvest period 2023
The materials for d'Yquem 2023 state that the harvest took place from September 14 to October 11. Even within a single vintage, the harvest does not always finish in one day. This provides clues for thinking about the progression of botrytization and the time needed to select grapes.
Variety and composition are separate numbers.
The blend is 70% Sémillon and 30% Sauvignon Blanc. Residual sugar is 153g/L, and alcohol is 14%. The former shows variety composition, the latter are finished wine components; even if on the same table, these numbers have different meanings.
Read the units of acidity.
Total acidity is stated as 3.68 g/L (as sulfuric acid), and pH as 3.85. Total acidity and pH are not the same, and you cannot directly compare the figures with total acidity measured as tartaric acid. Don’t judge sweetness only by residual sugar, and check how acidity is displayed as well.
What to align and what to compare.
2023 varieties
- Conditions to standardize
- Château d’Yquem
- Conditions for comparison.
- 70% Sémillon, 30% Sauvignon
- Additional points to confirm
- blend of the finished product
Residual sugar and alcohol
- Conditions to standardize
- Château d’Yquem
- Conditions for comparison.
- 153g/L・14%
- Additional points to confirm
- Both the unit and denominator differ.
Total acidity and pH
- Conditions to standardize
- Château d’Yquem
- Conditions for comparison.
- 3.68g/L (expressed as sulfuric acid) · 3.85
- Additional points to confirm
- Do not equate the amount of acidity with pH.
Order of reading and key points to consider in each article
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READ · HYPOTHESIZE · RECONSIDER
Château d’Yquem Source Analysis: Sweet Wine Sugar and Acidity
Compare the stated conditions in the documentation. Numbers specifying vintages should be treated as information for that specific year.
This summarizes materials published by producers, regional groups, and importers. Each source includes the publisher and the date the material was checked.
| Comparison items | What can be determined from the materials | Ability to distinguish by reading |
|---|---|---|
| 2023 varieties | 70% Sémillon, 30% Sauvignon | blend of the finished product |
| Residual sugar and alcohol | 153g/L・14% | Both the unit and denominator differ. |
| Total acidity and pH | 3.68g/L (expressed as sulfuric acid) · 3.85 | Do not equate the amount of acidity with pH. |
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Read the explanation for each question
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What does 70% indicate?
These are the percentages of the blend.
What should you confirm before comparing total acidity with other sources?
Total acidity values calculated as sulfuric acid and those calculated as tartaric acid cannot be directly compared. A total acidity of 3.68g/L is specified as calculated as sulfuric acid. If another source uses tartaric acid, you need to first standardize the basis. pH 3.85 is a separate indicator and should not be interpreted simply by subtracting it from total acidity.
What can be explained from 153g/L residual sugar?
Distinguish sugar level from the sensory impressions related to acidity and other factors.
Basis and sources for the exercise
Practice exercises in comparison
Please explain differences in raw materials and winemaking by reading the table and sources.
Read examples of organizing comparisons
| Conditions for Comparison | Comparison items | What can be determined from the materials | Ability to distinguish by reading |
|---|---|---|---|
| 2023 varieties | 70% Sémillon, 30% Sauvignon | blend of the finished product | |
| Residual sugar and alcohol | 153g/L・14% | Both the unit and denominator differ. | |
| Total acidity and pH | 3.68g/L (expressed as sulfuric acid) · 3.85 | Do not equate the amount of acidity with pH. |
Sources of materials used for comparison are listed in the text and exercises.
Explain in your own words
Introduce the 2023 d’Yquem by providing its grape varieties, residual sugar, and acid stats, and give one example of something that cannot be determined from the numbers alone.
Check after writing
- Did you specify the label, vintage, and scope of materials to be compared?
- Did you distinguish and explain the three items in the table?
- Did you separate verified facts from points to check further with additional references or tasting?
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