FDNS 1301 Introduction to Foods Understanding Vegetables

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FDNS 1301Introduction to FoodsUnderstanding
Vegetables
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 Vegetable Composition

•      based upon classification type     
  similar to fruit      water     
  carbohydrates      increased cellulose (fiber)

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Classification or Types of Vegetables

• 1)          leaves (lettuce)2)          stems
  (celery)3)          bulbs (onion)4)         
  fruits (tomato)5)          roots
  (carrot)6)          tubers (potato)7)         
  flowers (cauliflower)8)          seeds (green
  peas)

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 Selection Characteristics

•       dependent on structure type      
  color      smell or odor      weight     
  mold free      clean or debris free     
  check stem end

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Storage Concerns 

•       washing      refrigeration     
  temperature and moisture
•       want to prevent water loss           
  revitalize by soaking in cold water

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Color Concerns  

• 1.  Solubility in Water2.  Effects of
  Cooking3.  Effects of Acids4.  Effects of
  Alkali5.  Effects of Metals

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Types of Pigments
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Chlorophyll

•       makes carbohydrates in plants     
  stored in chloroplasts (slightly insoluble)
•       acid and overcooking turns to dull olive
  green (pheophytin)      alkali turns to bright
  green (chlorophyllin)
• increased solubility and poor taste

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Caratenoids 

•       normally yellow/orange and sometimes red
  or pink      slightly insoluble in water     
  acid reduces the pigmentation      alkali has
  no effect      long cooking may reduce the
  intensity of color

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Anthocyanins 

•       red, purple or blue colors      very
  water soluble      acid turns pigment
  red      alkali turns pigment purple or
  blue      metal ions (tin or iron) turns it
  violet or blue

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Betalain 

•       purple red or yellow      very water
  soluble      exposure to acid will make it
  slightly brighter red
• Exposure to alkali will shift red to yellow
•       becomes pale when overcooked

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Anthoxathin 

•       also known as flavones or flavonols     
  white or colorless      very soluble in
  water      acid turns it white      alkali
  turns it yellow      long cooking times darken
  the pigment and sometimes turn it pink     
  iron turns it dark      aluminum turns it
  bright yellow

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Flavor ComponentsCabbage

• sulfur compounds (sinigrin) when cut break down
  to mustard oil      overcooking heightens
  process

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Onions

• when cut, sulfur and enzymes react to irritate
  eyes and nose

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Potatoes 

• green parts from solanine (bitter alkaloid)

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Cooking Preparation 

•       trim      washing      peeling

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Changes during Cooking

• 1.  gelatinization of starch granules2. 
  kill microbes3.  loss in chemicals4. 
  oxidize vitamins5.  increased water absorption
  (diffusion and osmosis)6.  mechanical losses
  from agitation, overcooking, paring7.  fiber
  changes (alkali softens, acid has no effect)

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Dried Legumes 

•       must be cooked      proteins
  available      gelatinize starch     
  increased flavor      decreased toxic
  substances      increased water and cellulose
  breaks down