Food Preservation

Question 1

What are two characteristics of the most perishable foods?

Answer 1

High protein and/or water content

Question 2

What are the 3 types of changes that can lead to food spoilage

Answer 2

Biological
Chemical
Physical

Question 3

What 2 things happen during biological food spoilage?

Answer 3

Sugars are fermented (yeast, bacteria)

Toxins are produced (bacteria, molds)

Question 4

What are the 2 categories of chemical changes leading to food spoilage? Name examples.

Answer 4

Enzymatic (protease/lipase.. degrade prot/TGs..)

Nonenzymatic (fat oxidation, Maillard rxn)

Question 5

What can be an effect of nonenzymatic chemical changes?

Answer 5

Decrease in bioavailability of proteins

Question 6

Name a few types of Physical changes leading to food spoilage (3)

Answer 6

Dehydration
Emulsion breakdown
Physical damage

Question 7

What are 4 ways products can be dried in a commercial setting?

Answer 7

Conventional (heat)
Vacuum (low pressure)
Osmotic (use a strong syrup)
Freeze-drying (ice crystals vaporize)

Question 8

What is curing?

Answer 8

Use of salt (with sugar/spices/nitrates) to dehydrate the product

Question 9

What is a side effect of fermentation on a product

Answer 9

Creates changes in flavor, color, texture

Question 10

How can pickling be achieved?

Answer 10

Acidification by adding acid or through fermentation

Question 11

What are the 4 benefits of Edible Coating

Answer 11

Increases shelf life (retains moisture and volatile cmpds)
Improves handling (less likely damageable)
Improves appearance (gloss)
Can add ingredients (antioxidants, antimicrobials)

Question 12

Below which pH are acidic foods safe for boiling water canning?

Answer 12

4.5 or below

Question 13

What is sous-vide cooking

Answer 13

It is a way to cook foods at a lower temperature for longer and allows better reproductibility

Question 14

What is ohmic heating and for what food is it good for?

Answer 14

Electrical current generating heat passing through food that destroys microorganisms; liquid eggs, fruit juices

Question 15

At what temperature should products be refrigerated for Cold Preservation?

Answer 15

]0°C, 4°C]

Question 16

What is the main advantage of Freezing for Cold Preservation

Answer 16

The water is made unavailable for the microorganisms

Question 17

Where are the ice crystals located in rapidly Vs. slowly frozen foods? What is a consequence?

Answer 17

Rapidly: intracellular
Slowly: extracellular –> induce loss of juices

Question 18

What two changes can happen during freezing storage other than water crystallization inside the product?

Answer 18

Freezer burn (Evaporated water freezes on the surface)
Oxidation (Undesirable browning due to polyphenolases; Ascorbic acid loss by ascorbate oxidase)

Question 19

Why does blanching raw produce before frozen storage helps?

Answer 19

Denatures enzymes responsible for oxidation
Better texture and color
BUT destroys Vit C and Folate