A Gentle Explanation of the Risk of Poor Coloration in Red Wine: What Happens Due to Global Warming and How to Prepare

A Gentle Explanation of the Risk of Poor Coloration in Red Wine: What Happens Due to Global Warming and How to Prepare

2025年07月19日 15:36

Table of Contents

  1. Why "Poor Coloration" is a Hot Topic Now

  2. What Does "Coloration" Refer To?

  3. Main Mechanisms by Which Global Warming Lightens Colors

  4. Impact on Japan's Climate and Major Varieties

  5. Changes Occurring in Global Production Areas

  6. Specific Impacts of Poor Coloration on Quality

  7. Main Countermeasures (Vineyard, Varieties, Winemaking, Data)

  8. For Foreign Readers: Characteristics of the Japanese Wine Market and Tourism

  9. Future Outlook and Summary

  10. List of Reference Articles


1. Why "Poor Coloration" is a Hot Topic Now

In the past, many cool climate regions (e.g., northern France in the past, Hokkaido) struggled with "insufficient ripening and pale color." However, in recent years, the rise in global average temperatures and the increase in extremely hot days have exceeded the "optimal coolness" during the ripening period, resulting in a reverse phenomenon where pigment formation is inhibited. Additionally, while sugar accumulation progresses rapidly in high temperatures, the maturity of aroma, color, and tannins ("phenolic maturity") often lags, leading to a "mismatch."



2. What Does "Coloration" Refer To?

**Coloration (Pigmentation)** refers to the process where the skin of the fruit changes from green to red/purple, primarily due to the accumulation of natural pigments called anthocyanins. Color is not just about appearance; it is also related to antioxidant properties, the structure of taste (astringency, structure), and stability during aging. More important than intensity are "vividness," "depth," and "uniformity," and a lack of these can lead to impressions of a pale appearance, early brick-red coloration, and monotonous aroma.



3. Main Mechanisms by Which Global Warming Lightens Colors

FactorWhat HappensImpact on Color (Brief)
High Daytime Temperatures (e.g., near 35°C)Pigment synthesis enzymes slow downNew anthocyanin accumulation decreases
Rising Night TemperaturesIncreased respiratory consumption & acid reductionHigher pH leads to dull, unstable color
Excessive Direct Sunlight & SunburnSkin damage, oxidationBrowning, spotting, uneven extraction
Extreme Water StressReduced leaf area, decreased photosynthesisImbalance of sugar/pigment
Premature RipeningSugar leadsImmature color and aroma make harvest decisions difficult
Rising pH & Acid ReductionWorsened conditions for pigment stabilization (flavonol polymerization)Easily fades
Drying Heat from WindWater imbalanceSmaller berries and uneven coloration


Point:"Heat does not necessarily mean darker colors"; exceeding optimal temperatures (around 25°C during the day, 15°C at night) can have the opposite effect.



4. Impact on Japan's Climate and Major Varieties

Japan is characterized by a monsoon climate, high humidity, and lingering summer heat, with many regions having small day-night temperature differences, leading to situations where "nights do not cool sufficiently," which increasingly suppresses pigment formation.


VarietyMain ChallengesBrief Comments (Examples of Responses)
Muscat Bailey APale color, acid reductionAvoid partial leaf removal to prevent sunburn, control yield
Pinot NoirLoss of delicate aromaHigh-altitude, cool vineyards, early morning harvest
MerlotSugar leads, high alcoholDelayed pruning, covering to moderate ripening
Cabernet SauvignonAcid deficiency in warm regionsClone selection, acid retention techniques
SyrahSunburn spotsLight shading of clusters with canopy



Regional Examples (Overview)

  • Hokkaido: Expansion as a future major red production area. Less heat stress, vibrant colors expected.

  • Tohoku: Potential for extended growth period. Room for quality improvement with temperature difference management.

  • Koshin (Yamanashi, Nagano): Existing central areas. Reorganize vineyards utilizing altitude differences.

  • Northern Kanto to San'in: Risk of extreme heat. Urgent need for precise shading and irrigation.

  • Kyushu: Securing night temperatures is the most challenging in response to extreme heat. Consider relocation to high altitudes and heat-resistant varieties.



5. Changes Occurring in Global Production Areas

RegionObserved Trends (Brief)Main Responses
BordeauxEarly ripening, increased alcohol, color stability issuesIntroduction of new permitted varieties (e.g., Trousseau), adjustment of trellising
BurgundyColor and acid reduction in hot yearsUtilization of north-facing slopes, restraint of leaf removal
RiojaDryness + high temperaturesHigh-altitude vineyards, water management
California (Napa, etc.)Heatwaves, wildfire riskPrecision irrigation, shading materials
AustraliaExtreme heat, droughtHeat-resistant rootstocks, nighttime irrigation
Southern Chile/UK/Northern EuropeDevelopment of new cool climatesRapid growth but consistency in maturity is a challenge


Globally, existing renowned regions are in a "managing over-ripeness risk" phase, while emerging cool regions are in a "establishing stable annual reproducibility" phase, leading to a polarization.



6. Specific Impacts of Poor Coloration on Quality

ItemImpact ContentWhat Consumers Feel
AppearanceLight ruby, early orange edgesYoung but with a sense of maturity/lightness
AromaMonotonous red fruit, lack of complexityImpression of "flat" and "short"
Flavor StructureLack of acid, high alcohol, weak astringencyFlabby taste, short finish
Aging PotentialAccelerated fading due to insufficient pigment polymerizationReaches peak quickly
BrandLow consistency in styleRisk of reduced repeat purchases



7. Main Countermeasures (Vineyard, Varieties, Winemaking, Data)

Vineyard Management

  • Optimization of Canopy Adjustment: Avoid excessive leaf removal to keep cluster temperatures down with "dappled shade."

  • Delayed Pruning/Two-Stage Pruning: Shift the ripening peak to a cooler period.

  • Shading Nets & Reflective Sheets: Reduce skin temperature and improve light distribution.

  • Precision Irrigation + Moisture Sensors: Avoid extreme stress.

  • Utilization of High Altitude, North Slopes, Sea Breezes: Ensure nighttime cooling.


Varieties, Clones, Rootstocks

  • Heat-resistant and deeply colored varieties (e.g., Syrah, Marselan) and acid-retaining clones.

  • Improved root exploration and water use efficiency with rootstocks.


Winemaking

  • Early morning harvest→Low fruit temperature.

  • Cold soaking→Gentle extraction.

  • Gentle extraction management (avoiding excessive stirring).

  • pH adjustment and acid correction.

  • Yeast selection (high color retention).

  • Micro-oxidation management to prevent fading.


Data Utilization

  • Real-time monitoring of cluster temperature, light, and moisture with IoT sensors.

  • Optimization of pruning and harvest timing with predictive models (accum

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