Fruits and Vegetables

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Fruits and Vegetables

• Chapters 12 and 13

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Definitions

• Plant items eaten with the main course of meal
  are considered to be vegetables
• Plant items eaten as a dessert are considered to
  be fruits

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Parts of plants used as vegetables

• Leaves beet greens, brussel sprouts, cabbage,
  chard, collards, dandelion, endive, kale,
  lettuce, parsley, spinach, turnip greens,
  watercress
• Stems asparagus, celery, kohlrabi
• Bulbs garlic, leeks, onion, shallots
• Roots beets, carrots, parsnip, radish, rutabaga,
  turnip
• Tubers artichoke (Jerusalem), potato (Irish)
• Flowers artichoke (Globe), broccoli, cauliflower
• Fruits cucumber, eggplant, okra, pepper,
  pumpkin, snap beans, squash, tomato
• Seeds beans (dry), corn, lentils, peas, soybeans.

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Fruits

• Berries small fruits, quiet fragile
• Grapes berries grown in clusters
• Melons large fruits with tough outer rind
• Drupes fruits containing single pit (apricots,
  cherries, plums, peaches)
• Pomes fruits that contain many pits (apples,
  pears)
• Citrus fruits fruits that are high in citric
  acid (oranges, grapefruits, lemons, limes,
  tangerines)
• Tropical, subtropical fruits bananas, dates,
  figs, papayas, mangoes, pineapples.

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Fruits

• Classification Exceptions
• Is a Tomato a Fruit or a Vegetable?
• 1893 US Supreme Court Ruled It Vegetable
• Botanically It Is Fruit
• Nuts Are Fruits
• Seeds Instead of Fleshy Fruit
• Grouped Separately
• Rhubarb
• Vegetable But Treated As a Fruit

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EGETABLESCOMPOSITION
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VEGETABLESPURCHASING
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VEGETABLESPURCHASING
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FRUITSPURCHASING
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Gross (proximate) composition of vegetables
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Proximate composition of fruits
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VEGETABLESCOMPOSITION
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Vitamins and minerals

• Green and leafy veggies -substantial amount of
  vitamins A and C, riboflavin, Ca, Fe
• Fruit and flower veggies- high in vitamin C, Ca
  and Fe
• Pod and seed veggies good source of proteins,
  but proteins lack some essential amino acids
  good source of vitamin B and trace minerals -Zn
  and Cu
• Roots and Tubers high in carbohydrates
• Minerals in plant materials are not readily
  available due to presence of phytic acid, oxalic
  acid, fibers

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FRUITS
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Fruits Composition

• Organic Acids
• Volatile Vaporize During Heating
• Nonvolatile Do Not Vaporize
• Leach Out When Cooked In Water
• Citric Citrus Fruits Tomatoes
• Malic Apples Apricots Cherries Peaches
  Pears Strawberries
• Tartaric Grapes
• Oxalic Rhubarb
• Benzoic Cranberries

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Fruits Composition

• Acidity of Fruits
• pH Value Below 5.0
• Tartness Related to Acidic Content
• Least Acidic Fruits
• More Bland Sweet
• Ph gt 4.5
• Most Often Vegetables

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Proximate composition fruits and vegetables is
affected by

• Botanical variety
• Cultivation practice
• Weather conditions
• Soil
• Degree of maturity before harvesting
• Storage conditions
• Processing method

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Quality indicators

• color
• size
• texture
• flavor
• nutrient content
• These indicators are affected by
• ripening
• storage
• processing

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Color and food acceptance

• Color far out weights flavor in the impression it
  makes on consumer, even when the flavors are
  pleasant and the food is popular one.
• Color powerfully influences not only the
  consumers ability to identified the flavor, but
  also his or her estimation of its strength and
  quality.

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Plant Pigments

• Chlorophylls
• Carotenoids
• Anthocyanins
• Flavonoids
• Enzymatic browning reaction
• Other discolorations

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VEGETABLESCOMPOSITION
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Summary of natural pigments
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Anthocyanins

• Anthocyanidinsugar anthocyanin
• Anthocyanidins cyanidin, petunidin, peonidin,
  malvidin, pelargonidin
• Pelargonidin - red cyanidin-reddish blue
  delphinidin - blue

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Anthocyanidins -chemical structures
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Examples of anthocyanidins in selected foods
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Anthocyanins are affected by exposure to

• Elevated temperature
• Increased sugar content
• pH
• Metal ions

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Carotenoids-classifications

• Carotenes - hydrocarbons
• Xanthophylls - contain oxygen in the form of
  hydroxyl, methoxyl, carboxyl, keto or epoxy
  groups.

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Carotenoids-classifications

• Acyclic - lycopene
• Monocyclic - g-carotene
• Bicyclic - a-carotene, b-carotene

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Chemical structures of some carotenoids
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Carotenoids - nomenclature

• Prefix neo- is used when at least one cis double
  bond is present
• Prefix pro- is used when poly cis bonds are
  present
• Prefix apo- designates carotenoid that is derived
  from another by loss of structural component

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Carotenoids in selected foods
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Carotenoids - processing

• Common food processing methods have only minor
  effect on carotenoid, but oxygen and light are
  the major factors contributing to carotenoid
  breakdown

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Chlorophylls -chemical structure
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Chlorophylls - effect of processing
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Enzymatic browning reaction

• PHENOL OXYGEN QUINONES
• THIS REACTION IS CATALYZED BY ENZYMES PHENOL
  OXIDASE, PHENOLASE, POLYPHENOLASE.
• QUINONES READILY POLYMERIZED TO BROWN PIGMENTS

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Fruits
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Enzymatic browning reaction -methods of control

• PHENOL OXYGEN QUINONE
• we can only control the contact oxygen and the
  activity of enzyme
• pH
• blanching
• Reducing contact with oxygen

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Fruits control of browning reactions

• Food Additives in Fruits
• Additives to Prevent Browning
• Sulfites Sorbates Benzoates
• Sulfites Sensitivity
• Sulfur Dioxide
• Sodium Sulfite or Bisulfite or Metabisulfite
• Potassium Bisulfite or Metabisulfite
• Ascorbic Acid Vitamin C
• Sorbic Acid Sorbate
• Benzoic Acid

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Ripening-changes

• Size
• Texture
• Softening of fruits - due to changes in pectic
  substances
• Hardening of veggies - due to deposition of
  lignins
• Starches
• In fruits are converted to simple sugars
• In veggies - starch content may be increased as
  result of converting simple sugars to starches
• Flavors in fruits organic acid content
  decreases, simple sugar content increases,
  astringency of fruits decreases due to formation
  of insoluble polymerized phenolics.
• Ripening can be controlled by storing plant food
  under modified athmosphere conditions (Carbon
  dioxide, ethylene)

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Fruits - ripening

• Fruit Ripens Becomes Overripe Pectin ?gt
  Pectic Acid

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Fruit processing -osmosis/diffusion

• Cell walls of fruits and veggies are
  semipermeable
• Transport of molecules through semipermeable
  walls is called osmosis and is controlled by
  osmotic pressure. Solution with the higher
  content of solutes exert higher osmotic pressure.
• Placing of piece of fruit or veggie in water
  brings about movement of water into cells. The
  increase in water produces swelling known as
  turgor pressure (crispiness, plumpness)
• Placing of piece of fruit in syrup brings about
  the movement of water from cell into syrup. Fruit
  will shrivel
• When osmotic pressure exerted by syrup osmotic
  pressure of cell piece of fruit or veggie will no
  gain or loose weight.

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Cooking of fruits

• most fruits edible without cooking
• texture of cooked fruits is softened by changes
  in hemicellulose, starches and protopectins.
• texture of cooked fruits depends on
• amount of moisture in fruit
• fruit structure
• amount of water used
• cooking time

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Cooking of fruits

• Makes cell membrane permeable due to coagulation
  of proteins attached to membrane and changes in
  pectic substances.
• At the first stage of cooking fruit become
  translucemt as result of expulsion of
  intracellular air.
• Color changes are due to changes in acid
  content, alkaline reaction of water, presence of
  metal ions.
• Flavor of fruits is formed by acids, esters, and
  sugars and is affected by cooking time

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Vegetables

• Vegetables are cooked
• to retain or improve nutrient availability
• to produce more palatable food (color, texture,
  flavour)
• Nutrients are lost upon cooking by
• leaching into cooking water (sugars, starches,
  minerals, ascorbic acid, vitamin B)
• chemical decomposition (heat, pH)
• oxidation
• isomerization (carotenoids trans to cis)

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Vegetables

• Losses of water soluble nutrients depend on
• Heating medium used (water, steam, frying oil)
• Amount of water
• Surface area exposed to water
• pH of water as leaching of acids increases
  destruction of ascorbic acid and thiamin.
• Flavor of vegetables is formed by acids, sugars,
  phenolic substances, volatile oils. Flavor
  composed may decomposed upon cooking - short
  cooking time will minimize losses.

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Brassica genus vegetables

• Have mild flavor when raw.
• Strong flavor develops upon cooking due to
  decomposition of sulfur containing compounds
  called glucosinolates.
• H2S and other volatiles are formed. The rate of
  decomposition increases in the presence of acids.
  
• This decomposition can be reduced by keeping lid
  off during initial cooking period, cooking
  vegetables in large amount of water, and short
  cooking times.

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Alium genus

• Onions, garlic, leeks, shallots
• Very strong flavor of garlic as well as onion
  volatiles responsible for tears are products of
  enzymatic reactions. Cutting, bruising activates
  enzymes.

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Allium genus
Compounds responsible for allium genus flavor
are escaping with steam upon cooking.
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Vegetables -Color

• Yellow vegetables contain mostly carotenoids.
  Prolonged heating in the presence of acids leads
  to isomerisation of carotenoids and color
  fading. Some veggies may darken -reason unknown.
• Red vegetables may contain anthocyanins or
  betalains. Acidic condition intensified color,
  alkaline conditions brings about changes in color
  to purple, blue, or green.
• White vegetables contain colorless flavonoids
  (anthoxanthins). In alkaline conditions these
  pigments tend to turn creamy to yellow and after
  prolonged cooking to dark brownish gray. Addition
  of acids help to retain white color.

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Vegetables -Color

• Green vegetables - upon cooking quickly changes
  from bright translucent green to olive green. The
  formation of olive green color due to replacement
  of Mg in chlorophyll by hydrogen ions. Addition
  of baking soda neutralize acids and chlorophyll
  is converted to bright green chlorophillin.
  However texture become mushy and thiamin is
  destroyed. Green color of veggies may be preserve
  by cooking in boiling water without lid (at least
  3 minutes) quickly as possible, addition of
  vegetables to boiling water, cooking in excess of
  water.

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Veggies - texture

• Softening due to changes in hemicellulose,
  pectins and starches.
• Cooking does not tenderized woody vegetables
  because they contain high level of lignins.
• Addition of acids slow down softening process.
• Alkaline conditions accelerate softening.
• Presence of calcium ions (hard water, molasses,
  calcium salts) slow down softening due to
  formation insoluble calcium pectate,. Cooking
  time must be increase in order to soften veggies.

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Processing of Plant Foods

• Harvesting and processing is rigidly scheduled
• Plant food must be cooled if not processed
  immediately.
• During storage there is continuous loss of
  moisture due to transpiration, respiration, and
  drying
• Loss of moisture can not be effectively prevented
  by hermetic packaging.
• Processing may involved washing, skin removal,
  blanching.

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Preservation Methods

• Canning
• Freezing
• Refrigeration
• Drying
• High sugar content (fruits)
• Concentrating (juices)
• Fermentation
• Pickling

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Fruits - storage

• Fresh Fruit
• Ripe Fruit w/ High Water Content
• Consume w/i 3 Days of Purchase
• Once Ripe Increase Storage Time By
• Placing In Plastic Bags w/ Air Holes
• Refrigerate

• Canned Fruit
• Keep Quality Longer
• Store In Dry Place Temperatures
• lt 70F 21C
• Discard If Cans Are
• Bulging
• Dented
• Leaking
• Rusted

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Fruits- storage

• Many Fruits are
• Picked Shipped In Unripe State
• Transportation may Damages Delicate Fruits
• Unripe Fruit
• Left At Room Temperature In Paper Bag Until Ripe

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LEGUMES Leguminosae/Fabacae

• Legumes Beans Peas Lentils
• Excellent Sources of Fiber Protein Iron
• Complex CHO
• All Legumes Grow As Seeds w/i a Pod
• Dietary Staple Since the Bronze Age
• Soybeans Relatively High PRO Fat
• TVP Meat Analogs Tofu Fermented Soy
• Phytochemicals
• Antinutrients
• Hard-to-cook beans

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LEGUMES

• Soybeans
• Textured Vegetable Protein
• Meat Analogs
• Tofu
• Fermented Soybean Foods
• Miso Natto Sufu Tempeh Tamari

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Definitions

• Tofu, also known as soybean curd, is a soft,
  cheese-like food made by curdling fresh hot
  soymilk with a coagulant. Traditionally, the
  curdling agent used to make tofu is nigari
  (magnesium and calcium chlorides) a compound
  found in natural ocean water, or calcium sulfate,
  a naturally occurring mineral. Curds also can be
  produced by acidic foods like lemon juice or
  vinegar. The curds then are generally pressed
  into a solid block. Types of tofu hard, soft,
  silken (glucono delta-lactone). Depending on the
  coagulant used in manufacturing, the tofu may
  also be high in calcium and magnesium. Tofu
  contains soy isoflavones.
• Tempeh is an Asian food prepared by fermenting
  cooked or/and uncooked soybean with Rhizopus
  with a texture similar to that of soft tofu and a
  yeasty, nutty flavor.
• Miso is a traditional Japanese food produced by
  fermenting rice, barley and/or soybeans with salt
  and the mold