Food science tutorials

Question 1

fresh or cellular foods are made from what

Answer 1

animal/plant tissue

Question 2

what are the orders of structure in natural foods (3 different levels)

Answer 2

Atoms -> Molecules –>Macromolecules –>Supra-molecular complexes -> Organelles -> Cells -> Tissues
[chemistry, biochemistry]

Tissues ->Organs ->Systems ->Whole organism [physiology]

Whole organisms -> Communities -> Ecosystems [biology]

Question 3

what is the basic structure unit for animal foods

Answer 3

muscle/ meat structure

Question 4

how long is a muscle cell, myofibril

Answer 4

1 metre long

Question 5

what is myofibril surrounded by

Answer 5

sarcolema (cell membrane)

Question 6

what is the order for myofibrils

Answer 6

Myofibrils -> muscle fibers ->higher orders of muscle structure or whole meat [increasingly complex structure]

Question 7

what is Muscle supplied with

Answer 7

blood vessels

Question 8

what examples of connective tissue

Answer 8

Muscle is supplied with blood vessels; these and covering fascia and tendons are all connective tissue

Question 9

what gives meat its tough texture

Answer 9

tendons and other connective tissue

Question 10

what fills muscle cells

Answer 10

sarcoplasm

Question 11

what does the sarcoplasm contain

Answer 11

organelles (mitochondria, lysozomes, endoplasmic reticulum, nucleus) and enzymes of glycolytic and Krebs cycle

Question 12

what is the energy source for meat

Answer 12

glycogen

Question 13

where are High amounts of myoglobin are found

Answer 13

aerobic muscle or “red meat”

Question 14

what does white meat contain

Answer 14

White meat (esp. poultry & fish) contains low levels of myoglobin

Question 15

look at diagrams in booklet

Question 16

what do Plant leafy tissue components include and what do they contribute to

Answer 16

epidemal cells, parachymer cells, phloem, xylem
(all contribute to structure)

Question 17

what do the seeds & roots of many plants contain

Answer 17

vast quantities of starch granules

Question 18

why is the large central vacuole of plant cells important

Answer 18

Provides outward pressure leading to firmer texture
* Compartmentalizes phenol,
organic acids and other waste
components
* Separates phenol substrates
from the enzyme PPO in the cytoplasm and so avoids browning in the absence of tissue damage

Question 19

what does the cell wall of plant cells consist of

Answer 19

The cell wall consists of a multiple layer of cellulose and hemi-cellulose fibrils embedded in a pectin comment Cell wall components may be lignified producing woody- texture

Question 20

what are prepared foods typically made from

Answer 20

secondary ingredients

Question 21

what are the structures of secondary ingredients

Answer 21

fabricated not cellular

Question 22

Food structure involves interactions between

Answer 22

water, polysaccharides, proteins and lipids.

Question 23

what are the 3 main colloidal systems

Answer 23

emulsions, foams, gels

Question 24

what are the 2 major classes of food emulsions

Answer 24

1. Oil inwater(O/W)emulsionsaremadefromlipid(oil)phasedispersewithinacontinuous
   water phase (e.g. milk)
2. Water-in-oilemulsionismadefromwaterphasedispersedwithinanoilcontinuousphase
   (e.g. margarine)

Question 25

what does the droplet size of O/W emulsions determine

Answer 25

milky colour

Question 26

The type of emulsion formed depends on the surfactant used, which can be

Answer 26

Inedible: detergents or soaps
Edible: monoglycerides, diglycerides,
phospholipids and Tweens, Span & Food
proteins

Question 27

what is Emulsion destabilization caused by

Answer 27

• Creaming
• Flocculation
• Oswald ripening

Question 28

what are food foams

Answer 28

A foam is air droplet surrounded by water layer Surfactants are needed to produce stable foams Examples of edible foams include:
* whipped topping
* head on a pint of Guinness * ice cream (a frozen foam) * bread (heat set foam)

Question 29

what are food gels

Answer 29

Gels are a 3D-network of food polymers, with large amounts of entrapped water that provide structure and texture to a food. Unstable food gels contract by expelling water leading to syneresis.
* Polysaccharide gels can be formed with any straight chain polymer, e.g. amylose, pectin * Example protein gels include:
 formed with egg white/blood proteins in heating
 Casein forming an acid coagulated gel at pH 4.6 (yoghurt)  Casein gels after hydrolysis by chymosin (cheese)

Question 30

what are some examples of multiple structures in prepared foods

Answer 30

Cooked minced meat > emulsion-gel | Bread > heat set foam-gel | Whipped cream > foam-emulsion

Question 31

what are emulsions, gels and foams all form the basis of

Answer 31

structure

Question 32

what are examples of emulsions

Answer 32

oil-in-water, or water-in-oil milk, butter margarine mayo

Question 33

what are examples of foams

Answer 33

air droplets in water phase- bread whipping topping

Question 34

what are examples of gels

Answer 34

3-dimensional network of biopolymers that hold large amounts of water
Jelly, jam
Egg white
Yoghurt, cheese

Question 35

what are the main sources of variability

Answer 35

production, processing, analytical

Question 36

what substance are involved in the Maillard reaction

Answer 36

chemical reaction between amino acids and reducing sugars that gives browned foods their desirable flavor. The compound that participates in the Maillard reaction is Glycine

Question 37

what are colloidal systems

Answer 37

give structure, texture, mouthfeel to different products- colloids are formed when one substance is dispersed through another, but does not form a solution. There are many types depending on the state of the 2 substances mixed together e.g gels/foams

Question 38

what is the difference between true solutions, suspensions and colloidal systems

Answer 38

true solutions have solute particles at the molecular level and do not scatter light, suspensions contain visible solid particles that settle out over time, and colloidal systems consist of colloidal particles that are intermediate in size between true solutions and suspensions