Stimulating beverages by niusheng11


									    Plant Secondary Metabolism
    (aka, natural products chemistry)

Definition of secondary (2o) products/metabolism:
-not essential & not found in all plants
-primary functions of 2o products-
        -defense against herbivores & pathogens
        -attraction of pollinator & seed/fruit dispersers
         (through scent, sight, and taste)

-important to humans in medicine, industry, food & agriculture
-most crop plants have been selected to make low levels of 2o
-three major categories of 2o cmpds

  1) Isoprenoids (or terpenes)

  2) Phenolics

  3) Nitrogen-containing compounds
(1) terpenes (aka, isoprenoids):
-largest category
-built from 2C (acetyl CoA) & 5C (isoprene) compounds
-isoprene subunits used to build larger molecules
-some terpenes are primary metabolites (e.g., pigments, hormones)
-2o cmpds often localized to trichomes or resin ducts
         -monoterpenes (10C)- pyrethroids & oils (e.g., pine oil, lemon
           oil, menthol)
         -sesquiterpenes (15C)- gossypol
         -diterpenes (20C)- resins (e.g., in pines and euphorbs)
         -triterpenes (30C)- phytoecdysones (insect molting hormones),
                   limonoids (in citrus rind), cardenolides (glycosidic
           triterpenes; e.g., digitalis & those in milkweeds)
         -polyterpenes (>40C)- natural rubber & latex
(2) phenolics:

-produced via shikimic acid pathway in plants, fungi, & bacteria, but not in animals
(which is why animals can't make tryptophan, phenylalanine, & tyrosine)

        -lignin (complex polymer built mostly from 3 kinds of phenolic-alchohol

                  -anthocyanins (pigments)
                  -flavonols (eg, UV-absorbing cmpds found in flowers, UV-screening
                    cmpds found in epidermal cells; these cmpds don't absorb 400-to-
                    700-nm light)
                  -isoflavonoids (e.g., phytoalexins...anti-microbial cmpds)

         -tannins (several different categories...big and small; general toxins)
                   -others (e.g., salicylic acid & coumarins)
         -others (e.g., salicyclic acid, coumarins)
(3) N-containing cmpds:

-many different kinds

      -alkaloids (N-containing ring, often basic)
               -mustard glycosides
               -cyanogenic glycosides
      -non-protein amino acids & oligopeptides
        (e.g., defensins, thionins)
      -proteins; e.g., proteinase inhibitors, lectins ((CH2O)n-binding
        proteins, a.k.a. agglutinins), cytochrome P450
        monooxygenases, etc.
Stimulating beverages

    Coffee, tea, cocoa
             History of coffee
• Native to E. Africa; used first in Ethiopia.
• Arabs were first to brew coffee (ca. 1300 AD)
  and use spread from Arabia to Egypt and then to
  Europe (ca. 1600).
  – Arabic origin: mocha, kava, coffee
• Coffee was particularly popular in England.
• Arabs monopolized trade by boiling seeds to kill
  them, but Dutch and French were able to obtain
  seeds and grow the trees themselves.
• Brazil and Columbia currently lead the world in
  coffee production.
• Second to oil, coffee is the most widely traded
Rust epidemic in coffee
• In 1868, Ceylon was the leading coffee producer (export
  of 100 million lbs); by 1890, no coffee could be exported
• leaf disease caused by a fungus, Hemileia vastatrix
• Java 1876; East Africa 1894; Brazil 1970
• made worse by limited diversity; highly variable
• controlled by fungicides --> uneconomical in many
  regions, except where optimal climate
• genetic resistance: C. canephora (Robusta); lower
  quality used in cheap blends and instant coffee
• replace by other crops: e.g., tea
Views of coffee change through
• hailed as a medicinal cure-all
• others condemned it as the devil's brew
  – usually for political or religious reasons
• mid 1900‟s: research discovered caffeine
  & its relation to human health
  – in moderation, coffee consumption is usually
    not a health risk
  – can indeed confer some health benefits
   • Small evergreen tree or shrub
     with shiny, simple leaves.
   • Traditionally a „shade‟ tree.
   • Fruit = berry (“cherry”).
   • Each fruit contains 2 seeds =
     beans, mostly endosperm.
   • Coffee is best grown in tropical
     and subtropical high-land cool
     climates, with fertile soils and
     60-100" rainfall, but requires
     dry season for flower
     development. Frost sensitive.
   • Trees begin producing at 3
     years and produce for 40
               Coffee species
             (of ca. 60 in genus)
• Coffea arabica - 90% of world's production
   – Only kind grown in Latin America, ca. 1% caffeine (on
     DW basis), milder than other species
• C. canephora -9% - Robusta coffee
   – Grown in Africa & Asia
• C. liberica - 1% - Liberian coffee
   – Grown in Africa
• The last two are hardier plants than C. arabica,
  and C. canephora produces more fruits, but C.
  arabica still predominates.
• C. arabica is a self-compatible polyploid, other
  are self-incompatibile diploids with a more bitter
Processing coffee
         • Seeds are separated
           from fruit, fermented and
         • Light roast-to-Dark
           Roasts (stronger flavor
           due to roasting at higher
           temperature; beans are
           oily-appearing because
           high temperature brings
           oils to surface).
           Most coffees sold in U.S.
           are light- and medium-
           Famous coffee types
• Light roast
   – Pronounced nut-like flavor, high coffee acidity
• Medium roast
   – Pronounced caramel like flavor, full coffee flavor, with some loss
     of acidity
• Full roast
   – Full coffee flavor, good balance of acidity and sugar
• Vienna
   – Dark roast flavor
• French Roast
   – Bitter, smoky taste and pungent aroma
• Espresso Dark
   – Burnt flavor that is strong and sweet
• Kona Coffee
   – the only coffee found in the Hawaiian Islands
   – Full coffee flavor, balance of acidity and sugar
           Coffee preparation
• Expresso
  – Pressurized hot water quickly forced through finely,
    ground & densely packed, dark roasted arabica
• Latte
  – Expresso with steamed milk
• Mocha
  – Latte with less steamed milk, but with chocolate syrup
• Cappuccino
  – Expresso with less steamed milk than a latte, but with
    large cap of foamed milk
        Secondary processing
• Instant coffee
  – ground beans brewed under pressure, dehydrate
    brew by freezing or spraying
• Decaffeination
  – before roasting, when beans are still 'green',
  – removing about 97-98%
  – Solvent - methylene chloride or ethyl acetate is used
    to remove caffeine, solvent is removed (hopefully)
    during roasting. Caffeine is removed from solvent with
    water and crystallized.
  – Water - green beans are percolated with water that
    contains all water-soluble compounds found in coffee
    with exception of caffeine, which diffuses out; more
    expensive than solvent extraction.
• Chemical name, 1,3,7-trimethylxanthine; an
• dimethylxanthine derivatives, theophylline and
  theobromine, are also found in a variety of
• occurs naturally in the leaves, seeds, or fruit of
  more than 60 plant species; coffee beans are ca.
  1-2% caffeine by weight
• discourages grazing animals
• 75% of purified caffeine (2 million pounds) is
  used in soft drinks, rest in headache and cold
         Caffeine continued
• readily absorbed into the blood and body
• half-life of approximately four hours (1-10)
• rapidly metabolized and excreted
• smokers break down caffeine more quickly
  than non-smokers
• contraceptive pill & pregnancy slow the
  rate of caffeine metabolism
• Effects range from mild alertness to
  heightened anxiety and body tension.
• Medically, caffeine is useful as a cardiac
  stimulant, and also as a mild diuretic.
• Recreationally, it is used to provide a "boost of
  energy" or a feeling of heightened alertness.
• Temporary increase in the metabolic rate and
  the rate of fat breakdown (lipolysis).
• minor diuretic under normal consumption
• beverages containing caffeine should not
  be used to promote fluid replacement
  during prolonged exercise
• Caffeine's effects are more mild than
  amphetamines, cocaine, and heroin, but it
  is manipulating many of the same
• Some regular users who stop consuming
  caffeine may experience withdrawal
  symptoms, including: drowsiness,
  headaches, irritability, nausea and
  vomiting, and depression.
Amounts of caffeine per item (mg)    Typical
Coffee (150ml cup)
Brewed, drip method                     115
Brewed, percolator                      80
Instant                                 65
Decaffeinated                            3
Espresso (30ml cup)                     40
Teas (150ml cup)
Brewed, major brands                    40
Instant                                 30
Iced (240ml glass)                      45
Some soft drinks e.g. cola (180ml)      18
Chocolate milk beverage (240ml)          5
Milk Chocolate (30g)                     6
Dark chocolate, semi-sweet (30g)        20
Cooking chocolate (30g)                 26
      Caffeine & related stimulants
       Alkaloid: methylxanthines
Compound       Source     effect
Caffeine       Coffee,    Stimulant of central
               tea, cola  nervous system, cardiac
               nuts       muscle, and respiratory
                          system, diuretic
Theophylline   Tea        Cardiac stimulant,
                          smooth muscle relaxant,
                          diuretic, vasodilator
Theobromine    cocoa      Diuretic, smooth muscle
               bean, cola relaxant, cardiac
               nuts & tea stimulant, vasodilator
    printed labels from a
     Japanese Tea Box
(antique mall in Grand Island, Nebraska)
The Cup of Tea. Mary Cassatt,
     1880, oil on canvas.
  American. Impressionist.
The Tea Cup. Jackson Pollock, 1946, oil on
 canvas. American. Abstract Expressionist
• World‟s most popular beverage, next to water
   – Every day, 800 million cups or glasses of tea are consumed
• Camellia sinensis - native to China/India/Tibet/Burma
  area; cultivation and use of tea originated in Asia (China
  or India, probably 4-5000 years ago).
• Portuguese & Dutch introduced tea to Europe inca.
  1600; tea was important trade item in Europe by 1700.
• Colonial Americans were fond of tea and were angered
  by tea tax imposed by British, which resulted in the
  Boston Tea Party.
• Cultivation: has not been grown very
  successfully in New World, except Argentina:
  most tea is grown in Asia.
• Plants are small evergreen trees, which prefer
  abundant rainfall and warm-to-cool temperatures
  (but no frost).
• Trees are pruned to force bush-like growth.
• Picking is by hand, youngest leaves and terminal
  bud only are picked; plants can be picked once
  a week. Tips are orange pekoe; larger leaves
  are souchong and pekoe.
• Tea bags were initially used as samples.
 Fermentation & additives affects
     color, flavor and aroma
• Non-fermented: e.g., Green Tea,
  Lungching (Dragonwell), Pilochun,

• Semi-fermented: Oolong

• Light: Chinchua, White tea
      • + Flowers: Jasmine tea
      • + Bergamot oil: Earl Gray

• Fully-fermented: Black or „red‟ tea
   – 95% of tea consumed in US
     Essential oils and tannins
• Essential oil: theol
• Tannin
  – Discourage herbivores
  – Used as stains, dyes, inks, tanning agents
     Benefits of drinking tea?
• Improving immune system and preventing
• Slowing down aging process
• Preventing loss of bone calcium
• Alleviating blood lipoid, cholesterol, blood
  pressure, and arteriosclerosis
• Helping sterilization and reinforcing teeth
  and intestine
• Reducing urine hyperacidity and gout
• Eliminate body fat
• Preventing sunburn and resisting UV
 Charleston, SC Tea Plantation
Some other plants used for “tea”
• Sassafras albidum - aromatic bark used to
  make medicinal tea; may be carcinogenic.
• Herb teas - made from a huge variety of
  fragrant plants (chamomile, chicory, etc.)
• Ginseng - Panax quinquefolium - use roots
  roots to make tea, straight tea does not
  taste very good so is usually used with
  honey or herb tea. Thought to have many
  positive affects, especially by Asians.
• Ephedra species – “Mormon” tea

The “Food of the Gods”?

• Theobroma cacao - chocolate and cacao
• New World origin in eastern Andes, "Food of
  the Gods" to Mayans, Mayan drink included
  cacao, red pepper, vanilla and other spices.
• Sweet hot chocolate became very popular in
  Europe by 1650 (introduced ca. 1500).
  Spanish, then Dutch, then Germans, became
  involved in establishment of cacao plantations.
• W. Africa and Brazil are now world's largest
• Cacoa plants are small trees grown in shade, in warm
  wet tropical climates.
• The pods contain 20-50 seeds, are broken open and
  cleaned by hand.
• Seeds are fermented, which changes their white color to
  purple. Seeds are very bitter at this point. Seeds are
  then roasted, cracked to remove seed coats to yield nibs
  (cotyledons), nibs are ground, making enough heat to
  melt fat and produce chocolate liquor which can be
  molded into baking chocolate.
• Cocoa is made by pressing out fat (cocoa
  butter), dry powder is treated with alkali to
  produce Dutch cocoa.

  Milk chocolate is produced by continuous
  stirring of a mixture of chocolate liquor +
  cocoa butter + sugar + condensed milk.
          Processing of Chocolate

•   Growth                          •   Crack, fan, winnow
•   Harvest                         •   Grind
•   Ferment                         •   Mix
•   Dry                             •   Refine
•   Ship                            •   Conch
•   Roast                           •   Temper
      What chemicals does
       chocolate contain?
• Caffeine and theobromine are both
  considered alkaloids (or methylxanthines).
• Phenylethylamine is an anti-depressive
  and anti-stress agent.
• Serotonin is a hormone which is also
  produced naturally by the brain.
• Various flavonoids
  different types of chocolate
• Unsweetened or Baking :
  – chocolate liquor that has been cooled and hardened.
• Dark or Bittersweet Chocolate:
  – must contain a minimum of 34 percent cacao solids.
• Semi-sweet Chocolate
  – chocolate with extra cocoa butter and sugar added.
• German Chocolate:
  – sweeter and richer than semi-sweet chocolate, and is
    a special blend of chocolate, sugar and cocoa butter.
• Milk
  – creamy sweet chocolate that has extra cocoa butter,
    sugar, milk, and vanilla.
• Cocoa
  – chocolate liquor with the cocoa butter having been
    removed, creating a fine bitter tasting powder.
• Dutch Process Cocoa
  – special process used to neutralize the natural acids in
    cocoa powder.
• White chocolate:
  – cocoa butter without the cocoa, and is therefore not
    considered chocolate.
  – cheap imitations that substitute vegetable oil for
    cocoa butter.
• Decorator’s or Confectioner’s Chocolate
  – a chocolate flavored candy.
     Chocolate factory tours
            Other beverages:
• Kola tree- Cola nitida - relative of cacao; native
  to W. Africa.
• original Coca Cola had seeds cleaned and
  allowed to ferment, then dried and pulverized to
  a powder.
• seeds contain caffeine and kolanin (heart
  stimulant) and appetite suppressant.
• Since 1903, the cocaine has been removed
  before the coca extracts are added.
      Other beverages, cont.
• Root beer - carbonated, sweetened
  beverage flavored by extracts (caramel,
  sarsaparilla, wintergreen).
• Teas (e.g., mate) made from various
  species with caffeine (e.g., Ilex species)
  are common in S. & C. America.

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