Grape Composition and Ripening:

1
Lecture 2

• Grape Composition and Ripening
• Viticulture from the Plants Perspective

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Reading Assignment
Text, Chapter 2, p. 13-52
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Characteristics of Plants

• Stuck where they are use chemical strategies to
  deal with problems
• Nutrient limitation
• Competition
• Excess/shortage of water
• Extremes of temperature
• Disease/Pest pressure
• Lack of light

4
Characteristics of Plants

• Prioritize nutrient use for survival
• Role of fruit
• Dispersal of seed
• Fruit is attractive to mobile agents that will
  disperse seed (animals insects birds)
• Seed itself designed to taste bad so it will
  not be consumed

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Characteristics of Grapevines

• Grown in a wide variety of soils/climates
• Persist in nutrient deficient soils
• Crop set happens in previous season
• Dormant buds developmentally programmed in prior
  season
• Extensive root structure can represent up to 90
  of the mass of the vine

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Factors Impacting Grapevine Performance

• Soil
• Topography/Location hillside, valley floor
• Disease/Pest pressure impacts composition of
  fruit

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Factors Impacting Grapevine Performance

• Climate
• Temperature
• Sunshine
• Humidity
• Rainfall
• Evaporation
• Wind
• Water availability

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Factors Impacting Grapevine Performance

• Microclimate
• Climate of individual vines heating of vineyard
  floor
• Climate of individual clusters
• Shading effects
• Humidity retention

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Factors Impacting Grapevine Performance

• The Human Element
• Irrigation practices
• Use of fertilizers
• Timing of treatments
• Canopy management
• Trellising system
• Use of rootstocks
• Pruning practices
• Cluster manipulation leaf removal, dropping of
  fruit

10
Berry Structure

• Skin 3 layers
• Epidermis
• Hypodermis
• Outer mesocarp
• Fleshy mesocarp
• Brush and center septum
• Vascular system
• Ovular
• Ventral
• Dorsal
• Seeds

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AJEV (1987) 38(2) 120-7
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Berry Development Maturation of Fruit Follows
Maturation of Seed

• Flowering/Fertilization
• Green Berry Stage
• Cell division occurs
• Acids accumulate
• Veraison
• Color changes occur
• Ripening
• Berry swells and softens
• Sugars Water Acids

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Factors Affecting Berry Development and Maturation

• Climate Warmer mature faster, less acidity,
  less color, higher pH, fewer late berry
  characters
• Variety Mature at different rates
• Disease/Pest pressure alters composition of
  fruit, alters timing of development
• Balance of vine carbohydrate demands of vine
  versus fruit versus level of photosynthesis

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Berry Composition at Harvest

• g/L
• Sugar 200
• Organic Acids 10
• Amino Acids 5
• Phenolics 2-5
• Volatiles trace
• Water 800

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SUGARS (hexoses) glucose fructose sucrose S
ucrose is the circulating product of
photosynthesis cleaved to produce glucose and
fructose in berry
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SUGARS (pentoses) arabinose xylose Not
metabolized by yeast
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Sucrose glucose fructose Allows for
accumulation of sugar in berry
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ORGANIC ACIDS malate tartrate
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MALATE COOH From the TCA cycle
HOCH Cytoplasmic CH2 Used for energy
generation COOH
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TARTRATE COOH Accumulates in vacuole
HOCH From ascorbic acid and
5-ketoglutarate HCOH COOH
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Amino Acids glutamate glutamine arginine alan
ine proline Typically comprise 90 of all amino
acids
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Amino Acids High ?-Amino Butryic Acid (GABA)
indicates fruit was held at a high temperature
post-harvest
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Phenolics Large Variety Found as tartaric acid
esters Caftaric Acid Most Prevalent
HO HO CHCH-CO-Tartate
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Volatile Compounds terpenes esters
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Sulfur-Containing Compounds glutathione
(glu-cys-gly) cysteine methionine
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AJEV (1987) 38(2)120-7
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Location of Compounds in Berry
Sucrose Glucose
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Location of Compounds in Berry
Malate Tartrate
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Location of Compounds in Berry
Phenols
Phenolic compounds
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Location of Compounds in Berry
Potassium
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Location of Compounds in Berry
Inorganic anions