Freezing

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Total cards: 24•Content version: v4•Public deck•Updated: 8/1/2026

Card preview (24)

Front (Question)

why is super cooling needed?

Back (Answer)

ice crystals don’t form at exactly 0 degrees; need super cooling to arrange in lattice structure

Front (Question)

freezing refers to storage of food between ___ and __ degrees C

Back (Answer)

-18; -30

Front (Question)

3 stages of freezing curve?

Back (Answer)

removal of sensible heat (liquid), removal of latent heat (liquid and solid), removal of more sensible heat (solid)

Front (Question)

why is there continual decline in freezing point for food materials?

Back (Answer)

presence of solute depresses freezing point–>pure water freezes out, unfrozen region gets very concentrated, FP v even more

Front (Question)

what is freezing range?

Back (Answer)

between 0 and -5 degrees C

Front (Question)

slow freezing leads to formation of ___ number of ___ ice crystals

Back (Answer)

small; large

Front (Question)

effects of slow freezing?

Back (Answer)

1) damage cell structure, loss of structural integrity 2) pull water out of cell due to osmosis (cell dehydration) 3) cells can’t maintain rigidity when thawed

Front (Question)

why is disruptive effect of size of ice crystals minimal in MFP?

Back (Answer)

elasticity of cell structure in muscles

Front (Question)

why is there still some quality loss in muscle food when frozen?

Back (Answer)

denaturation of muscle proteins because during freezing, unfrozen region become [ ] with enzyme and acids which denature proteins

#10

Front (Question)

rate of freezing influenced by:

Back (Answer)

temp differential, heat transfer rate, SA of food, product thickness, agitation of liquid

#11

Front (Question)

commercial freezers at ___C, domestic at ___C

Back (Answer)

-25; -18

#12

Front (Question)

what happens to ice crystals when re-freeze?

Back (Answer)

size increases

#13

Front (Question)

decrease in humidity in freezer leads to ______ on food surface

Back (Answer)

sublimation of ice (freezer burn)

#14

Front (Question)

what is sublimation?

Back (Answer)

ice–>vapour (solid–>gas)

#15

Front (Question)

relative humidity inside freezer should be kept above ___%

Back (Answer)

#16

Front (Question)

food is ____ prior to freezing

Back (Answer)

glazed

#17

Front (Question)

what is glazing?

Back (Answer)

formation of water layer on food surface that turns into ice coat, protects food from moisture loss

#18

Front (Question)

types of heat transfer systems:

Back (Answer)

air cooling, plate cooling, cryogenic cooling (can be direct or indirect)

#19

Front (Question)

types of freezers

Back (Answer)

air-blast, tunnel, belt, fluidized bed, contact, scraped surface, cryogenic

#20

Front (Question)

freezer used for ice cream manufacture

Back (Answer)

scraped surface

#21

Front (Question)

cryogenic freezing uses liquid ___ or ___

Back (Answer)

nitrogen (-196C); ammonia (-33)

#22

Front (Question)

what is IQF?

Back (Answer)

Individual Quick Freezing

#23

Front (Question)

IQF used for:

Back (Answer)

frozen fruit processing

#24

Front (Question)

why do frozen concentrated juices exhibit low Vit C loss?

Back (Answer)

low pH, low O2, low water activity