Nutrition 240 Chapter 30

Front 1

Clarence Birdseye

Back 1

1. food tech pioneer, started freezing fish in 1920's

Front 2

Freezing process

Back 2

1. temp of food lowered to freezing

2. ice crystals form

3. temp of product lowered to storage temp

Front 3

slow freezing or sharp freezing

Back 3

temp range 25 to -20F, takes up to 10 hours to freeze

Front 4

quick freezing

Back 4

temp range -25 to -40F, takes up to 2 hours to freeze

Front 5

cryogenic freezing

Back 5

temp range -76F or lower, tiny ice crystals

Front 6

Changes during Freezing, Storage, and Thawing

Back 6

1. formation of ice crystals

2. enzyme action

3. nonenzymatic oxidation

4. desiccation

5. activity of microorganisms

Front 7

Techniques for freezing fruit

Back 7

1. mix juicy fruit with sugar, or make sugar syrup

2. add vitamin C to control browning

Front 8

Techniques for freezing veggies

Back 8

1. blanch before freezing

2. prompt freezing after harvesting

Front 9

Techniques for freezing meat

Back 9

1. careful packaging

2. any size is fine

Front 10

Techniques for freezing eggs

Back 10

1. freeze whites or mixed whole eggs, not yolks by themselves

Front 11

Frozen food containers

Back 11

1. materials: metal, plastic, paper or fiberboard, moisture and vapor-proof materials

2. tight-fitting lids or closures

Front 12

Canning processes

Back 12

1. application of foods to temps high enough to destroy microorganisms

2. sealing of heated product in sterilized airtight containers to prevent recontamination

Front 13

History of Canning

Back 13

1. 1809: Nicolas Appert from Paris developed process with glass bottles and corks, heating them for processing

2. 1810: tin canister developed in England, Peter Durand got a patent

3. 1800s: canned foods produced in England for British Navy

4. 1874: retort for pressure canning developed in Philadelphia

5. 1860: Pasteur worked with micro-organisms, started scientific work in food spoilage

Front 14

retort

Back 14

1. equipment used in commercial canning to obtain necessary time and temp for food preservation

2. batch vs continuous

3. can agitate or rotate cans during processing

Front 15

retort pouch

Back 15

semirigid and flexible packages (ie tuna)

Front 16

raw-pack method of canning

Back 16

1. uncooked food placed in container

2. container filled w/boiling liquid

3. processed, water must be 140F

Front 17

hot-pack method of canning

Back 17

1. food heated in syrup, water, steam, or extracted juice to 170F

2. packed into container

3. processed, water must be 180F

Front 18

low-acid tomatoes and other veggies

Back 18

1. pH above 4.6 -- low acid

2. better to use pressure canner

3. otherwise, add lemon juice or citric acid to get correct acidity

4. temp should reach 240F

Front 19

pressure canner

Back 19

1. temp higher than 212F

2. atmospheric pressure decreased, boiling point decreased

3. boiling point of water increased inside pressure canner

Front 20

pressure canner structure

Back 20

1. rack in bottom to hold jars

2. vent port (or steam vent or petcock): drives out air and fill compartment with steam and then closed during processing

3. counterweight (weighted gauge): closes vent port

4. safety fuse or valve: steam can escape if too high in compartment

Front 21

pressure canner process

Back 21

1. 2-3 in water, jars inside, close lid

2. close lid, heat until steam for 10 min, close petcock

3. start timing when you have the correct pressure, regulate heat to keep pressure

4. when time done, turn off heat, let canner cool and depressurize

5. check seals 12-24 hours after