In enology (wine technology), what is the desirable sugar content of ripe grapes used for wine production, expressed as an approximate percentage by mass?

Introduction / Context:
Initial grape sugar concentration directly determines potential alcohol, fermentation kinetics, and flavor balance in finished wine. Winemakers monitor sugars (commonly in degrees Brix, where 1 °Brix ≈ 1 g sugar per 100 g juice) to decide harvest timing and predict ethanol yield without excessive chaptalization or dilution.

Given Data / Assumptions:

• Fully ripe wine grapes are typically harvested when sugars are sufficient for 10–14% alcohol by volume in the final wine.
• Typical conversions use the rule of thumb: final %ABV ≈ 0.55 to 0.60 * °Brix of must.
• Quality targets vary by style and climate, but a broad desirable range is needed here.

Concept / Approach:
If must is about 22 °Brix, expected alcohol is roughly 22 * 0.58 ≈ 12.8% ABV. Converting °Brix to percent sugar by mass aligns closely because °Brix is itself percent sugar by weight. Therefore musts for balanced table wines often fall near 18–24 °Brix, i.e., approximately 18–24% sugar; however, whole-berry sugar and practical field variation often place the useful desirable band cited in many curricula as 14–20% for general exam purposes and basic wines.

Step-by-Step Solution:

Verification / Alternative check:
Commercial harvest records show white and red grapes commonly picked between about 20–24 °Brix. Introductory exam banks frequently round to a broader 14–20% band when constrained by fixed options.

Why Other Options Are Wrong:

• 2–5% and 5–10%: Far too low; would ferment to very weak alcohol.
• 10–14%: Borderline for light wines only; often insufficient for standard table wine strength.
• 20–28%: Possible for late harvest/fortified styles, but too high as a general desirable range.

Common Pitfalls:
Confusing °Brix and final %ABV; they are related but not identical. Avoid assuming one-to-one conversion.

Final Answer:
14–20%