4b. Processing Tech for Roots and Tubers

Question 1

Cassava based products

Answer 1

• starch (tapioca)
• cassava flour
• modified cassava flour (mocaf)
• Asia flour
• cassava chips (fried)

Question 2

Tapioca production in small scale industry

Answer 2

1. peeled manually
2. washed and rasped (cell wall torn up, flesh turns to pulp, starch granules released)
3. pumped into inclined vibrating screen of diminishing mesh size
4. small spraying to assist separation of starch from fibrous matrix
5. starch granules carried w waterfall to bottom of tank
6. gravitational sedimentation
7. supernatant run off
8. starch cake (35-40% moisture) crumbled to 1-3 cm lumps and spread out on thin layer for sun drying
9. final mc 15%

Question 2

unit operations for peeling and washing cassava

Answer 2

• revolving drum w water sprayer
• perforated drum w paddle arms/spiral brush
• abrasive roller/disc

Question 3

HCN reduction in cassava flour occurs during

Answer 3

1. grating
2. pressing
3. sieving

Question 4

Compare tapioca w cassava flour

Answer 4

• more mc
• less ash
• less fat
• less fiber
• more carbs
• more starch
• more amulose
• less total sugar
• less HCN

Question 5

Use of tapioca

Answer 5

NON FOOD
coating, glue, paper, fabric, furniture

FOOD
thickener, infant food, sauce, filler, binder, biscuit

processed further to dextrin, glucose/fructose syrup, jam, jelly, confectionary, ice cream, ethanol fermentation, etc

Question 6

What is mocaf

Answer 6

Cassava flour produced from fermented cassava chips

LAB may be added or naturally present

Question 7

Diff between mocaf and cassava flour

Answer 7

• greater viscosity
• whiter color
• neutral aroma and flavor

Question 8

What is asia flour

Answer 8

pulp residue from cassava starch extraction

used for cassava crackers and low grade tomato sauces

Question 9

Preparation for potato processing

Answer 9

1. dry sorted
2. destoned
3. washed
4. peeled
5. further sorted and timmed

Question 10

How to destone

Answer 10

float potatoes in water

Question 11

Peeling of potatoes done with what

Answer 11

Carborundum rolls or brushes

immature tubers only require light brushing and usage of caustic soda/lye

Question 12

methods of preserving potatoes

Answer 12

canning, chipping, drying, freezing

Question 13

Potato canning

Answer 13

• 1.5% salt by weight
• Ca salts up to 0.051%
• low acid canned food process (30 in at 115.6C)
• cooling to 35C before being cased

Question 14

Dried potatoes

Answer 14

• cut to 3/8 x 3/8 pieces, blanched in hot water to deactivate enzymes, dried to prevent case hardening
• dried ro mc 3-4%, gas packaged w oxygen scavenger