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11:709:201-Tangel: Lecture 13
Vegetables
12
Science
Undergraduate 2
10/23/2007

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Cards

Term
What are vegetables?
Definition
  • Plants or parts of plants which are used as food.
  • Served raw or heated, they supply color, flavor, texture, and nutrients to the human diet.
Term
What are the primary nutrients  in vegetables?
Definition
  • Vitamin A precursor (beta carotene),
  • Vitamin C
  • Minerals, other vitamins (folate)
  • fiber
Term
What is parenchyma cell?
Definition

Major food source of plant structure.

Contains pulp, cytoplasm, organelles

Structure:

  • Cell wall:  Primary—loosely associated cellulose.  Secondary—condensed cellulose, hemicellulose, lignin, gums
  • Cytoplasm:  sticky gel-like compound found within the cell wall.  Surrounds and bathes the organelles (plastids)

Term
Name 4 types of Plastids.
Definition
  1. Chloroplasts - Contain chlorophyll
  2. Chromoplasts - Contain carotinoid pigments
  3. Leucoplasts - Location of starch storage
  4. Vacuole - Stores water, anthocyanins, flavors, sugars, salts, and organic acids
Term
What are pectic substances?
Definition

Pectin—generic term used to identify polysaccharides found if fruits/vegetables

  • Protopectin—large insoluble molecule
  • Pectin (pectinic acid)—produced by enzymatic action during ripening
  • Water soluble
  • Pectic acid—found in overripe fruits/vegetables (soft)
Term
How are vegetables classified? (7 classifications)
Definition

Classified by the part of the plant which is ussually consumed.

  1. Leaves:  Cabbage, Lettuce, all varieties, Spinach, Brussels sprouts - High water, fiber content, Generally low in calories, Vitamin A value
  2. Seeds: Contain germ to start new plant – Corn, Green beans, Peas - High in fat, protein + variable carbohydrate = high in calories
  3. Vegetable Fruit:  Produced from the ripened ovaries of flowering plants – Cucumber, Eggplant, Pumpkin, Tomato, Green pepper - Variable simple and complex carbohydrate content, many are high in water = variable calorie content from low to moderately high
  4. flowers:  Broccoli, Cauliflower - Contain sulphoraphane to reduce cancer risk - High water content, low digestible carbohydrate content = low calorie
  5. stems:  Transport system for plant – Celery, Asparagus - High in indigestible carbohydrate, water = low calorie
  6.  Roots/Tubers:  Storage of complex digestible carbohydrate – Potato, Yam/sweet potato, Carrot, Beet - High in calories
  7. Bulbs:  Onion, Garlic, Leek - Contain allydes which may reduce risk of heart disease, HBP - Moderate digestible carbohydrate = moderate calories - Slightly sweet 
  8.  

Term
What are carotinoids?
Definition
  • Yellow-orange color
  • Alpha, beta, gamma à yellow-orange
  • Lycopene—red-orange
  • xanthophyll--yellow
  • Beta carotene is converted to vitamin A in the body
Stability:   
  • Very slightly soluble in water
  • Susceptible to oxidation
  • Heat + acid à isomers of carotene (some are yellow)
  • Heat + alkaline à no effect

 

Term
What is anthocyanin?
Definition
  • Found in cytoplasm
  • Soluble in water
  • Heat + acid à red
  • Heat + alkaline à purple
  • Al, Sn, Feà purple, blue, green
  • Proanthocyanidin—found in cranberries
  • Yellow-white
  • Prevents E. coli from attaching to cells of the human urinary tract
Term
What is anthoxanthin?
Definition
  • Found in white potato, turnip
  • Soluble in water
  • Heat + acid à white
  • Heat + alkaline à yellow
  • Feà green, brown
Term
What effects does heat have on vegetables? (5 components change)
Definition
Changes:

  1. Texture—starch gelatinizes, cellulose softens, water is lost, Reduces bulk, Increases tenderness, Lignan—not softened by heat (Woody center of carrot, White end of asparagus, End of broccoli)
  2. Flavor—flavor rich components in organic acids, S-compounds, salts, volatile oils, carbohydrates and phenolic compounds
  3. Odor—cruciferous and allium vegetables are harsh
  4. Color—pH, heat and metals affect
  5. Nutrients—most are water soluble, use minimal water in preparation
Effects on pH:  pH 4.0 to 4.5 retards softening , Pectic substances are least soluble, Above or below this pH tissues will soften, Adding baking soda oversoftens tissues and destroys nutrients
Term
Why is flavor in vegetables volatile? (3 reasons)
Definition
  1. Escapes in steam and cooking water
  2. Flavor loss is heightened by prolonged cooking and too much water
  3. Long heating develops strong S flavor in cabbage and cruciferous vegetables, allium containing vegetables (Heat until fork-tender, with lid off)
Term
How do you heat vegetables? (4 ways)
Definition
  1. Steam:  Most cooked vegetables are steamed, Small amount of water is brought to a boil, Add vegetables, cover, 5-10 minutes, Fork tender, Tender-crisp
  2. Bake:  Dry heat, Usually hearty vegetable, like potato
  3. Stir-fry:  Small amount of fat, Continuous motion to prevent sticking
  4. Deep fat fry: Popular, Fat is absorbed by vegetable
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