BIO
201: Botany
PLANTS AND HUMANS - FOODS
(notes updated December 2010)
INTRODUCTION
Use of plants are important to humans in several ways
1) Food - most of world food derived from 12 plants
2) Medicine - many of pharmaceutical drugs from plants
3) Psychoactive - alter the way we think or act
4) Poisonous - detrimental to our health
Chemicals extracted from plants may fit into several of the above categories based on amount used
In cases 2-4 their are chemical produced by plants for defense
some with negative effects on our body (poison ivy)
some kill other organisms but not us (quinine)
Domestication of plants probably started in eastern Mediterranean
areas of Lebanon, Syria, Turkey, Iraq, and Iran about 11,000 year ago
First crops included: barley, wheat, peas
Later added were: chickpeas, olives, dates, pomegranates, & grapes
Grains were for carbohydrates, legumes for proteins
Other areas of early cultivation:
China (ca. 10,000 yr): rice & soybeans
Mexico & Central America (9000 yr):maize, lima beans, kidney beans, peanuts
Summary: 3 major areas of origin of agriculture between 8,000 and 10,000 years ago
TODAY'S MOST IMPORTANT FOOD PLANTS
1) WHEAT (Poaceae – grass family)
History: one of the oldest cultivated plants (Middle East ca. 9000 years ago)
Growth today: best growth in cool, dry climates (especially Russian & USA)
largest worldwide production plant
Food: three parts to grain (fruit) – endosperm, embryo, seed coat
Processing: each component has specific nutritional value
a) Endosperm to make white flour (mostly starch)
b) Embryo to make wheat germ (most vitamins + nutrition)
c) Seed Coat + Fruit used for bran (mostly cellulose = fiber)
2) MAIZE (= CORN) (Poaceae – grass family)
History: origin in Mexico with Mayans about 7000 years ago
Growth today: mostly grown in temperate and subtropical America
Food: grain (fruit) used for human foods
most used to feed livestock (entire plant)
source of oil from embryo
similar grain composition as wheat
Processing:
mostly use whole grain
exception when producing oil (from embryo component)
3) RICE (Poaceae – grass family)
History: origin probably in southeast Asia
found in 7,000 year old archeological sites in Thailand
Growth today: plant of humid tropics (requires warm temperatures & high moisture to grow well)
mostly in Asia
main food of 50% of world population
Food: grain (fruit)
very low protein content (7.5% of grain)
Processing:
threshing process removes the hulls to produce brown rice
polishing removes seed coat & embryo to produce white rice (mostly carbohydrate endosperm)
-- above three provide vast majority of world's food ---
4) WHITE (= IRISH POTATO) (Solanaceae – nightshade family)
History: origin probably in Peru or Bolivia (Andes Mountains of South America)
Growth today: worldwide in temperate zones & tropical highlands (needs cooler climates)
mostly grown in Europe now
Food: modified underground stem or rhizome = Tuber
5) SWEET POTATO (Convolvulaceae – Morning glory family)
Yam is a different plant
History: origin in lowlands of tropical South America
Growth today: very important in Asia, Africa and Polynesia (tropics)
grows as a vine
Food: enlarged storage root (tuber)
6) CASSAVA (= MANIOC) (Euphorbiaceae – Spurge family)
History: native to tropical South Amercia
Growth today: today in South America, West Indies, Africa, & Indonesia (tropics)
Food: enlarged root - up to 45 pounds
commonly made into flour for bread
we use as a source of flavoring tapioca
7) SUGAR CANE (Poaceae – grass family)
History: native to tropical se Asia
Growth today: worldwide in tropics
Food: stem (high sugar content – up to 20% of mass)
extraction by crushing and pressing out juice
evaporation to produce granular sugar
8) SUGAR BEET (Chenopodiaceae – Goosefoot family)
History: native to coastal western and southern Europe
Growth today: top three growers now: Europe, Russia and USA (cooler climates)
Food: sugar mainly in expanded taproot
red cultivar for food
white cultivar for sugar
leafy cultivar = chard
source of about 30% of world sugar
9) COMMON BEAN (Fabaceae – bean family)
History: indigenous to the Americas
Growth today: throughout New World
Food: fruit and/or seed eaten
many different varieties
10) SOYBEAN (Fabaceae – bean family)
History: native to eastern Asia
Growth today: major crop of Asia & USA
has become common to western hemisphere in last 50 years
USA now produces 50% of world crop
Food: seeds
oils, livestock food, fermented to tofu
good protein source
11) BARLEY (Poaceae – grass family)
History: native to Middle East
Growth: over half now grown in USA
Food: fruit (grain) used
originally made into a paste, toasted on stones (first breads?)
now used in feeding livestock & malting
12) SORGHUM (Poaceae – grass family)
History: native to east Africa (it is heat and drought resistant)
Growth today: main producers USA & India (tropics and subtropics)
Food: grain (fruit)
several different varieties for foods, molasses
also for livestock food, and brooms
13) COCONUT (Arecaceae – Palm family)
History and Growth today: native to tropical coastlines
continues to be most common there
Food: fruit – mainly the endosperm for food
three important parts to fruit
a) outer fibrous layers of fruit (pericarp)
fiber for mattress
torn off before shipping
b) inner layer of fruit (= pericarp) + hard seed coat (not used)
c) embryo + endosperm
initially the central liquid in noncellular stage
slowly becomes cellular to be the white "meat"
very nutritious but high in oils (used for food and cosmetics)
14) BANANA (Musaceae – Banana family)
History: southeast Asia
original species have pea-sized seeds
Growth: throughout tropics
must have 10-12 month growing season
Food: fruit consumed
type we see is the sterile triploid
seeds develop by parthenocarpy (pollination w/o fertilization)
black spots are aborted ovules
part eaten is placenta tissue of ovary
high in carbohydrates
two basic types on market:
a) Plantains – require cooking before eating (bitter)
b) Sweet bananas – type we see
Food plants can be categorized into four groups:
1) SUGAR AND STARCH PLANTS – main component is a carbohydrate
sugar plants: sugar cane, sugar beets
starch plants: rice (fruit), maize (fruit), sorghum (fruit), banana (fruit), white potatoes (tuber)
manioc (tuber), sweet potato (tuber)
2) PROTEIN AND OIL PLANTS – for protein and/or oils
protein: beans, peanut, brazil nut
oils: peanut, maize, coconut
3) SPICE PLANTS - add flavor to other foods
a) Nutmeg – native to Banda and Maluccas Islands (between Borneo & New Guinea)
(so famous that they became known as the “Spice Islands”)
use seed
brought to Europe about AD 600
such an important spice that traders didn't tell source
contains myristicin - a poison at 4 g (hallucinogenic)
b) Ginger – long known from southeast Asia
use rhizome
originally used to aid digestion
contain a number of chemicals
c) Black Pepper - from foothills of Himalayas (Asia)
use fruits – immature white and mature turn black
completely different family from peppers we see
require heat and humidity
d) Vanilla - in the orchid family, native to Mexico
vanillin is produced from the fruit (seeds and pericarp)
now most produced in Madagascar
vanillin is produced from the fruit
is not completely soluble in water so add some alcohol
4) DRINK PLANTS -
a) Coffee - back to about AD 1000 in near east & Ethiopia (ne Africa)
today #1 producer is Brazil - about 20% (tropics)
use the seeds (“beans”) - have about 1.3% caffeine
b) Tea - native to China - first recorded in BC 2700
in same genus as Camellias
leaves used - contain 2.7-3.3% caffeine, 0.2% theobromine
c) Cocoa (= cacao) – Don’t pronounce the last "A"
native to NW South America, basis of monetary system for Mayans & Incas in 1500's
now most production in equatorial Africa
fruit a berry - seeds (part used) is surrounded by a white sweet paste
seed 53% fat (= cocoa butter) + sugar to make chocolate
contain theobromine (1.2% of bean, 2.3% of cocoa powder)
d) Cola -- native to tropical Africa
seeds contain 2% caffeine & 0.05% theobromine
originally chewed by many to alleviate hunger, thirst & fatigue