Cryogenic Freezing Project

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Thomas E. Rippen
University of Maryland Sea
Grant
Andrew Tolley
Equipment Project Coordinator
Bill Sieling
Chesapeake Bay Seafood Industries Association

Strengths
◦ Can produce fresh, unpasteurized crabmeat
◦ Growing demand for local, fresh foods
◦ Local crabmeat recognized for high quality

Weaknesses
◦ Crabs are seasonal, best crabs when demand
◦ Still need a way to extend shelf-life and inventory
products
◦ Pasteurized crabmeat perceived as more highly
processed, less fresh
◦ Traditional cans are expensive, available from only
one manufacturer - must have a seamer for 401
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Appropriated by Congress
Administered in Maryland by MD DNR
Subcontracted to University of Maryland to
implement
Current funds allocated in two awards for
equipment, assistance (MCQAP and other
projects), marketing
Find alternative to pasteurizing in cans
◦ $392,000 for purchasing equipment
1 lb plastic cup
Fresh pack, used
for freezing in this
test.
401 diameter
pasteurized can
307 diameter
pasteurized can
Crabmeat containers
307 diameter
MD pasteurized
can
Panama 307 closing machine
Canco 60P 401 closing machine
$27,400, between “as is and
rebuilt” condition (Alard)

Dehydration
◦ Water migration and recrystallization
◦ Hydrophobic interactions

Concentration of reactants (What happened to Q10?)
◦ Enzymatic softening in some fish
◦ Formation of cross-links (e.g. formaldehyde from TMAO)
◦ Oxidation of oils (rancidity)

Protein denaturation and structural damage –
◦ Toughening
◦ Excessive drip
◦ Bland flavor

Oxidative changes
◦ Yellowing
◦ Off-flavors and odors




Pass through 27-15F quickly.
Target final equilibrium temp = storage temp
Use good barrier packaging
Hold storage temperatures steady
◦ Fluctuating vapor pressure accelerates sublimation
and accretion of ice crystals (a-axis and c-axis
growth)

Hold storage temperature as cold as
commercially feasible.
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Rapid freezing
Currently used in Maryland and elsewhere with
good experience
Product is thawed and sold as previously frozen
Studies show reduced tissue damage
◦ SEM (Giddings and Hall, 1976)

And improved sensory quality for short-term
holding (1½ months)
◦ Webb, et. al. 1976

Beyond 5-6 mos. pasteurization may be better
option
Vent
Relief
Valve
Liquid
LN2 Hose
Nitrogen
Dewar
Mini Freezer
Time Termperature of Freezing
Process, 75 lbs @ 60 minutes
30
25 (Goal)
20
Temp º F
10
0
-10
-20
0
5
10
15
20 25
30
35 40
-30
45 50
55 60
65
70
75
80 85
90
Time (Minutes)
Center of Can Temperature
3 Lbs
75 lbs
87 lbs
95 lbs
Cabinet Readout
104 lbs
112 lbs
-100
Freezer Readout
95 100 105
Interpretation of Data
Pasteurization as Baseline
3 Year Payback
Comparison of Equipment Combinations
Basic Information Generated from Phase 1
1 Process was determined for this equipment
Initial temperature, 31-34 º F
Freezer cabinet was set at -100 º F
The process time was 60 minutes
The batch size was 75 pounds
2
Liquid nitrogen usage was determined
5.2 pounds of crabmeat were frozen per gallon of liquid nitrogen
LN2 cost $4.98 per gallon
Approximately 19 batches of crabmeat were frozen (1425 lbs)
The cost of LN2 (without equipment or other charges) is $.96 per lb
of crabmeat
Basic Data Generated from Phase 1, con’t
3
Other equipment and storage options identified
Mini freezer (75 lb capacity) used in Phase 1
Batch freezer, single door (200 lb capacity)*
Batch freezer, double door (400 lb capacity)*
LN2 Dewars, 41 gallon, used in Phase 1
LN2 Bulk tank, 1500 gallon
4
Pros and Cons of equipment
5
Extended costs of equipment options
Fixed cost - outright purchase of freezers and installation
Lease costs-( 5 year contract) for bulk tank
Consumable costs- liquid nitrogen used for freezing
1
2
Mini and ewar
Mini and Bulk
3
Comparison
Mini Cabinet
Batch Cabinet
75 lb max capacity
200 lb max capacity
75 x 8 hours = 600 lbs per day
200 x 8 hours = 1600 lbs per day
Minimum vent requirements flexible
Fixed vent through roof
Requires stooping to load and
unload
Can utilize portable cart
Portable
Fixed location
Bulk Tanks for Liquid Nitrogen
Pros
Cons
Inventory management is
less complicated
Higher cost of concrete pad
Relief exhaust not in
process area
Higher piping installation
costs
“Lower pressure” nitrogen
is colder
5 year lease arrangement,
due 12 months per year
even if not in production
Nitrogen costs 1/5 of
dewar inventory
Space will be dedicated to
bulk tank pad and fence
Not necessary to change
tanks in middle of process
Nitrogen is delivered by
semi-truck
Tanks are “Pressure
Used smaller tanks (are
vessels” and are owned and available) for purchase but
inspected by nitrogen
subject to owner inspection
supplier
Freezer Cabinets
Mini Freezer
Batch Freezer
Double Door Freezer
75 lbs capacity
200 lb capacity
400 lb capacity
Too Small
Just Right
Too Large
Liquid Nitrogen Storage
BulkTank
Dewars
41 Gallon Capacity
1500 Gallon
Capacity
Expensive NL2 vs low rent
Cheap LN2 vs 5 yr lease
Recommendation:
Bulk and batch cabinet
Pasteurized vs Batch/Bulk NL2
Fixed Cost and Variable Cost
$10.00
$8.00
$6.00
$4.00
$2.00
20,000
17,500
15,000
12,500
10,000
7,500
5,000
2,500
Fixed Cost of Pasteurizing
Variable Cost of Pasteurizing
Fixed Cost of Batch Freezer/Bulk Tank
Variable Cost of Batch Freezer/Bulk Tank
Conclusion
• Mini Cabinet is too small
• Dewars are not practical for LN2 storage for crabmeat
processors
• A batch cabinet and bulk tank system are recommended
• A production range for a LN2 freezer system is at least 7,500 lbs
to 10,000 lbs per year (either in a single operation or a
combination)
Number of Responses
Compared to traditional packaging (metal can) how
would you rate this plastic tray?
Better
packaging
50
40
30
20
10
0
Much better
packaging
No difference
Poorer
packing
Much poorer
packaging
Compared to traditional packaging (metal can) how would you
rate this plastic tray?
Number of Responses
16
14
12
10
8
6
4
2
0
Much better
packaging
Better
Packaging
No difference
Poorer
packaging
Extremely poorer
packaging
Consumers indicating that the tray
was better or much better than the
metal can
Eastern Shore: 68 percent
Western Shore: 48 percent

CSF consumer survey
◦ Survey Taken During Seafood Cooking
Demonstrations at Harbor Day Event
◦ 64 completed the survey

Community Supported Agriculture
◦ Exploring potential for adding a seafood option
◦ Survey instrument prepared and sent to 350
members of existing CSA on Eastern Shore

1. Which locally caught species would make you
more likely to participate in a CSF program in
your area.
Crabmeat 44; Striped bass 31; Live crab 26,
Clams 25; Shucked oysters 20; Live oysters 20
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2. I prefer: fillets/steaks 41; whole fish 16;
headed/gutted 10; no preference 6
3. How often would your prefer to have these
types of seafood available (mixed products each
week/seasonally).
Bi-weekly 32; weekly 20; monthly 5; quarterly 1.
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4. Product available for pickup by you at set time
and location.
Average drive miles – 10;
weekday afternoons - 33; weekend mornings 30

5. On a scale of 1 to 10, would you sign up for a
CSF arrangement/contract based on the species
you chose above.
One (very unlikely) - 4; Two- 4 ; Three-3; Four4; Five-4; Six-0; Seven - 13; Eight - 3; Nine - 4;
Ten (very likely) - 22

Evaluate batch freezer performance under
commercial conditions.

Conduct retail sales study comparing skinpack trays to metal cans.

Conduct and monitor one or more alternative
marketing strategies, e.g. CSF.
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