Vegetables

I. Vegetables are vegetative, i.e., non -reproductive parts

A. may be modified roots, stems or leaves

B. most have relatively few calories and little protein, but high in vitamins, minerals, etc., see table 7.2

C. exceptions are "root crops" underground storage organs, most of which are not roots

II. Brassica oleracea - mustard family Brassicaceae

A. "cole crops" - cabbage, collard greens, Brussels sprouts, broccoli, cauliflower, kale, kohlrabi (also rape seed, canola oil)

1. all are modifications of various parts of the plant

2. domesticated by 650 B.C. in Greece

a. cabbage - head formed by suppression of terminal bud, cultivated for over 2,000 years, sauerkraut = shredded leaves packed into earthenware pots with salt and allowed to ferment, good source of vitamin C during the winter

b. Brussels sprouts - "miniature cabbages" formed when axillary buds for lateral heads, developed in 1818

c. kohlrabi - swollen stem bases

d. broccoli - swollen inflorescence containing a mass of fertile flower buds, will flower if not harvested

e. cauliflower - very densely packed white flower buds. Only the head of the cauliflower is eaten, a part known as the white curd. This stalk is surrounded at the base by thick, green leaves which are tied around the developing inflorescence to keep it white. Achlorophyllous varieties have been developed. High in vitamin C.

III. Lettuce Lactuca (Asteraceae)

A. lactuca comes from the word for milk because of milky sap

B. cultivated at least 6,500 years in Egypt

C. over 50 different varieties

D. formed by suppression of lateral buds that bolt if not harvested on time

E. three types

1. loose leaf - salad-bowl

2. head - iceberg name comes from the way the in the US in the 1930s. It was transported all covered in crushed ice - making it look like icebergs

3. cos - stiff elongated leaves, romaine

IV. Apiaceae - carrot family

A. celery Apium

1. petioles with swollen leaf bases

2. cultivated by ancient Greeks and Romans

B. carrot Daucus carota

1. a biennial that stores food reserves in a large taproot during first season to be used for flowering in second season

2. beta-carotene is two vitamin A molecules joined end to end, which is nearly identical to retinal, present in eye rod cells used at low light intensities

V. Beets Beta vulgaris

A. vegetable dish

B. mangel-wurzel - root fed to cattle

C. Swiss Chard - leafy vegetable

D. sugar beet - major source of sugar

1. eaten by Romans

2. recognized in 1747 as potential source of sugar

a. first commercial extraction in 1802

b. Napoleon recognized its potential and ordered research on it

c. sugar content has been increased from 6% to 20%

d. major source of sugar for most of Europe

e. hasn't replaced sugar cane in US due to higher cost

VI. Irish potato Solanum tuberosum

A. tuber = underground stem

B. high in carbohydrates, ranks fourth in the world as a food staple

C. native to South America and grown for at least 13,000 years

D. native Americans at high elevations, allowed potatoes to freeze overnight and then stomped on them to squeeze out the water, after a few days produced a dry mass called chuno

E. Spanish introduced potatoes to Europe first but independently introduced by several others

F. potato leaves are poisonous so some wary about eating at first

G. because of politics, cool moist soil, and high yields, the Irish became completely dependent upon potatoes, eating as much as 10 lbs./day 

1. between 1843-44 cool moist conditions allowed spread of potato blight Phytophthora infestans destroying virtually all crops within five years, millions of Irish died and millions emigrated to the US

H. until recently most potatoes grown from tubers, which promoted spread of disease, the new "Pioneer" variety can be grown from seeds, reducing disease and also allowing new breeding programs

VII. Manioc Manihot esculenta

A.  manioc, tapioca, cassava

B. most important tropical root crop for half a billion people worldwide, supplies 37% of calories consumed in Africa, 11% in Latin America, but very low in protein about 1%

C. grown for thousands of years, may have originated in Brazil

D. grows on very poor soil, in both wet and dry climates, easy to plant and produces after only 18 months

E. contain cyanic glycosides which upon bruising produce hydrogen cyanide

1. roots are shredded and pressed to rupture cells, then drained and allowed to sit overnight for gasses to escape

2. pulp is used to make a flatbread like a large pancake which can be stored for long periods

3. cooking drives off any remaining hydrogen cyanide

4. dried pulp is also ground into flour which stores for long periods, farofa = toasted flour, only food some native Brazilians eat

5. if the is flour heated on a hot metal plate or tossed into a hot metal drum it becomes gelatinized into pellets known as tapioca

VIII. Sweet potatoes and Yams

A. sweet potato is Ipomoea of the Convolvulaceae (morning glory family)

1. true root

2. native to South America, goes back at least 10,000 years

3. cultivated widely throughout the world

4. very little protein but high in beta-carotene

5. eaten like Irish potatoes in US, rest of the world used for starch, wine and alcohol production

B. Yam is Disocorea of the Dioscoreaceae (monocot)

1. appears to be a tuber, but some may be roots

2. native to Africa, South America and Asia, independently domesticated

3. many species are poisonous but peeling and boiling eliminates the poison

4. higher in protein than most other tuber crops

IX. Sugar cane Saccharum offiiciarum

A. a perennial grass probably originated in New Guinea

B. refining its sugar goes back at least 5,000 years in India

C. until 1500 honey was primary sweetener in Europe, sugar so scarce it cost nearly as much as gold

D. Columbus brought to New World on his second voyage where it became easy and cheap to grow

1. Sugar triangle between New England, Africa and West Indies

2. slave trade began because of sugar growing (not cotton) which required large amounts of manual labor

3. raw sugar (molasses) shipped to Connecticut where used to make rum, run sent to Africa to buy slaves, slaves brought to West Indies to work in sugar cane fields

4.  in 1764 British imposed a duty on sugar (Sugar Act) which started sugar smuggling in the colonies, a British customs vessel was burned and sunk, precursor to Boston Tea Party

E. sugar easy to propagate vegetatively via tillers that give rise to new stalks

F. sugar consumption relatively low in most parts of the world but typical American eats about 30 lbs/yr, plus 85 lbs/yr of corn sweeteners and 1 lb/yr of honey and other sweeteners

G. sugar production see Fig. 7.41

1. cane (stems) harvested at 22 - 24 months

2. canes cleaned then fed through rollers that crush them to express the juice

3. juice is boiled to kill microorganisms

4. lime is added to reduce acidity and clarify

5. juice is siphoned from the sludge at bottom of tank and filtered to remove particles

6. juice is heated to evaporate most of water

7. then poured into pans and subjected to a vacuum causing crystallization

8. after crystallization it is centrifuged to separate crystals of raw brown sugar from liquid molasses, raw brown sugar is shipped to refineries to make white sugar

9. crystals redissolved into a heavy syrup and centrifuged to remove any unwanted chemicals

10. a filtering agent such as diatomaceaous earth is added to clarify it

11. then filtered through bone char (bones heated to high temperatures in the absence of air to drive off volatile substances) to further clarify

12. then crystallized in large pans and spun in hot revolving drums to form large granules

13. powdered sugar made by finely grinding, corn starch is added to prevent clumping

X. Other vegetables/products

A. Artichoke - the immature inflorescences of Cynara, a thistle like member of the Sunflower family

1. the green parts eaten are the fleshy bracts (phyllaries) 

2. the "choke" is the undeveloped flowers and chaff

3. the heart is the swollen part of the receptacle

B. Asparagus - Asparagus officinalis (Liliaceae)

1. native to areas subjected to periodic burning in Mediterranean region

2. plant readily sprout up from underground rhizome

3. humans take advantage of resprouting ability by planting in areas where they die back in the winter and send up new shoots in the spring

4. shoots are harvested when they emerge from the ground, but a limited number can only be harvested or the plant dies

5. if allowed to develop the shoots become highly dissected cladophylls which resemble fern leaves 

6. the true leaves are reduced scales at the base of the cladophylls, figure 7.25

C. Maple syrup/sugar - primarily form the Sugar Maple Acer saccharum and Black Maple (A. nigrum)

1. traditionally small pipes are stuck into the phloem and buckets hung upon them to catch the sap, but plastic tubing with slight suction often now used

2. sap contains about 8% sugar (sugar cane has 22%)

3. sap is boiled down into syrup or even farther to form sugar

4. 40 gallons of sap produces one gallon of syrup