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Fruits and Vegetables

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Title: Fruits and Vegetables


1
Fruits and Vegetables
  • Chapters 12 and 13

2
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

3
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.

4
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.

5
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

6
EGETABLESCOMPOSITION
7
VEGETABLESPURCHASING
8
VEGETABLESPURCHASING
9
FRUITSPURCHASING
10
Gross (proximate) composition of vegetables
11
Proximate composition of fruits
12
VEGETABLESCOMPOSITION
13
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

14
FRUITS
15
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

16
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

17
Proximate composition fruits and vegetables is
affected by
  • Botanical variety
  • Cultivation practice
  • Weather conditions
  • Soil
  • Degree of maturity before harvesting
  • Storage conditions
  • Processing method

18
Quality indicators
  • color
  • size
  • texture
  • flavor
  • nutrient content
  • These indicators are affected by
  • ripening
  • storage
  • processing

19
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.

20
Plant Pigments
  • Chlorophylls
  • Carotenoids
  • Anthocyanins
  • Flavonoids
  • Enzymatic browning reaction
  • Other discolorations

21
VEGETABLESCOMPOSITION
22
Summary of natural pigments
23
Anthocyanins
  • Anthocyanidinsugar anthocyanin
  • Anthocyanidins cyanidin, petunidin, peonidin,
    malvidin, pelargonidin
  • Pelargonidin - red cyanidin-reddish blue
    delphinidin - blue

24
Anthocyanidins -chemical structures
25
Examples of anthocyanidins in selected foods
26
Anthocyanins are affected by exposure to
  • Elevated temperature
  • Increased sugar content
  • pH
  • Metal ions

27
Carotenoids-classifications
  • Carotenes - hydrocarbons
  • Xanthophylls - contain oxygen in the form of
    hydroxyl, methoxyl, carboxyl, keto or epoxy
    groups.

28
Carotenoids-classifications
  • Acyclic - lycopene
  • Monocyclic - g-carotene
  • Bicyclic - a-carotene, b-carotene

29
Chemical structures of some carotenoids
30
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

31
Carotenoids in selected foods
32
Carotenoids - processing
  • Common food processing methods have only minor
    effect on carotenoid, but oxygen and light are
    the major factors contributing to carotenoid
    breakdown

33
Chlorophylls -chemical structure
34
Chlorophylls - effect of processing
35
Enzymatic browning reaction
  • PHENOL OXYGEN QUINONES
  • THIS REACTION IS CATALYZED BY ENZYMES PHENOL
    OXIDASE, PHENOLASE, POLYPHENOLASE.
  • QUINONES READILY POLYMERIZED TO BROWN PIGMENTS

36
Fruits
37
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

38
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

39
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)

40
Fruits - ripening
  • Fruit Ripens Becomes Overripe Pectin ?gt
    Pectic Acid

41
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.

42
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

43
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

44
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)

45
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.

46
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.

47
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.

48
Allium genus
Compounds responsible for allium genus flavor
are escaping with steam upon cooking.
49
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.

50
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.

51
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.

52
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.

53
Preservation Methods
  • Canning
  • Freezing
  • Refrigeration
  • Drying
  • High sugar content (fruits)
  • Concentrating (juices)
  • Fermentation
  • Pickling

54
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

55
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

56
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

57
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60
LEGUMES
  • Soybeans
  • Textured Vegetable Protein
  • Meat Analogs
  • Tofu
  • Fermented Soybean Foods
  • Miso Natto Sufu Tempeh Tamari

61
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
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