4a. Roots and Tubers

Question 1

What are roots

Answer 1

ROOT TOBERS
modified lateral roots, enlarged to function as storage organ (e.g. sweet potato, cassava)

Question 2

Characteristics of roots and tubers

Answer 2

• source of carbs
• low in protein and fat

Question 2

What are tubers

Answer 2

STEM TUBERS
Enlarged or thickened rhizomes (underground stems) or stolons (horizontal connection betw organisms) used as storage organs (e.g. potato, yam, taro)

Question 2

Chemical composition of cassava

Answer 2

62-65 moisture
32-35 carbs
0.7-2.6 protein
0.2-0.5 fat
0.8-1.3 fibre
0.3-1.3 mineral

vits: B1, B2, niacin, C

Question 3

Characteristcis of cassava

Answer 3

lowland tropical crop
20 million tons prod/yr
yellow and white

Question 3

Major amino acids of cassava

Answer 3

isoleucine, leucine, lysine, valine (more in leaf than root)

Question 4

Potential toxin in cassava

Answer 4

HCN in the form of limarin (cyanogenic glucoside)

<50mg/kg not toxic
50-100 mg/kg partially toxic
>100 mg/kg toxic

More in peel than root, also in leaf

Question 5

Reducing HCN in cassava

Answer 5

soaking, boiling/steaming, drying, fermentation, water extraction, roasting, frying