9C

Question 1

describe the sharp freezing method

Answer 1

-23 to -30C, some air circulation

Question 2

describe last freezing

Answer 2

use of high velocity air

Question 3

expand IQF

Answer 3

individually quick frozen

Question 4

how is freezer burn prevented?

Answer 4

spraying a layer of water over product

Question 5

describe a scraped surface heat exchanger

Answer 5

cooling agent in exterior jacket = ethylene glycol

- high surface area

Question 6

describe immersion freezing

Answer 6

packaged product immersed in cooling agent like ethylene glycol, sugar or salt solution

Question 7

what are commonly used cryogens? what temperatures are they?

Answer 7

liquid nitrogen: -196C

liquid CO2: -79C

Question 8

how much heat is removed per kilogram of product by cryogenic freezing?

Answer 8

386 kj

Question 9

how do cryogens interact with food?

Answer 9

liquid nitrogen is sprayed on
solid CO2 is mixed w/product directly
high pressure liquid CO2 can be sprayed, but then turns to snow under lower pressure

Question 10

traditional methods of drying can reduce moisture levels to what percentage?

Answer 10

15%

Question 11

more advanced methods of drying can reduce moisture levels to what percentage?

Answer 11

1-5%

Question 12

The amount of moisture that air can hold at a particular temperature is…

Answer 12

relative humidity