Lecture 3 - Part 1

Question 1

it is the presence of a liquid, especially water, often in trace amounts. It is defined as the water in adsorbed or absorbed phase

Answer 1

Moisture

Question 2

amount of moisture in the grain expressed as percentage of the total weight of the sample,

Answer 2

Moisture content

Question 3

amount of water per unit mass of moist (or wet) sample

Answer 3

Moisture content, wet basis (MCwb)

Question 4

amount of water per unit of dry solids (bone dry) present in the sample

Answer 4

Moisture content, dry basis (MCdb)

Question 5

Most water in foods. It is lightly entrapped and therefore easily pressed or squeezed from food

Answer 5

Free water

Question 6

it acts as a dispersing agent and solvent and can be removed by drying foods

Answer 6

Free water

Question 7

can promote the growth of microoragnisms
Examples are citrus fruits, tomato, pineapple

Answer 7

Free water

Question 8

this water associates in layer through intermolecular hydrogen bonds around hydrophilic food molecules

Answer 8

Absorbed water (Capillary Water)

Question 9

Water is held tightly to proteins, or cell walls or protoplasm. It is not readily squeezed out of food

Answer 9

Absorbed water (Capillary Water)

Question 10

it refers to the hydration proteins such as starch. Examples are carrots, camote, radish, kamote

Answer 10

Absorbed water (Capillary Water)

Question 11

cannot be boiled or the water remains unfrozen below 0 degrees Celsius, usually -20 C

Answer 11

Bound Water

Question 12

water in food that is unavailable as solvent. Examples are egg white, egg yolk, meat and fish, cheese

Answer 12

Bound Water

Question 13

it is most easily removed from foods by evaporation, whereas more severe conditions are needed to remove chemically or physically bound water

Answer 13

Free Water

Question 14

What are methods of removing water or moisture??

Answer 14

Distillation Method
Oven drying method
Vacuum drying
Freeze-drying

Question 15

are based on direct measurement of the amount of water removed from a food simply by evaporation

Answer 15

Distillation Method

Question 16

what are the major uses of distillation in the food industry?

Answer 16

for concentrating essential oils, flavours and alcoholic beverages and in the deodorization of fats and oils

Question 17

it is a thermogravimetric method (water losses on drying) in which the sample is dried for a defined period of time at constant temperature.

Answer 17

Oven Drying Method

Question 18

allows dehydration to be carried out at low temperatures in a closed system. The heat transfer mode in vacuum drying is by radiation

Answer 18

Vacuum drying

Question 19

To increase the drying rate, it may be installed to allow conductive heat transfer

Answer 19

heating plates/ trays or heating chamber

Question 20

it can usually heat up foods up to 98-102 degrees celsius with low pressure of 25-100 mm of Hg.

Answer 20

Vacuum drying

Question 21

Lower temperatures (60-70 degrees celsius) are used for what? to prevent decomposition

Answer 21

high sugar food products

Question 22

it suited for drying high value liquid foods such as coffee and juices, as well as high value solid foods strawberries, shrimp, diced chicken, sliced mushrooms, and even steaks and chops

Answer 22

Freeze-drying or lyophilization

Question 23

method of grain moisture determination based on actual extraction of water either by convection heating (oven method) or distillation.

Answer 23

Primary Method

Question 24

method of grain moisture determination based on some characteristics of the grain sample such as electrical resistance and capacitance which are related to moisture content and must be periodically calibrated against and official primary method

Answer 24

Secondary Method