Frozen Product Forms

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Frozen Product Forms
At J.J. McDonnell our goal is to secure the freshest products direct from the source.
We offer a wide selection of fresh and frozen seafood and fish.
Below is the most common forms for Frozen Product

Frozen Seafood: Freshness Redefined

DEFINITION: The goal in freezing seafood is to bring the center of the product to a temperature of 0°F or lower as quickly as possible. Choice of freezing method — blast, cryogenic, plate or brine freezing — depends on product types, intended uses, packaging needs and cost.

Advantages

Quality. The texture and taste of quickly frozen fresh seafood is nearly the same as fresh. In fact, frozen-at-sea product is of much better quality than “fresh” fish that has been in a boat’s refrigerated hold for over a week.

Safety. When seafood is frozen and stored at appropriately low temperatures (at least minus 10°F), bacterial growth is arrested, preserving the product and dramatically extending shelf life.

Economy. High-quality frozen fish is not only superior to a stale, unfrozen product but is much less wasteful, easier to inventory and usually less expensive than fresh.

Variety. A wider range of frozen seafood is available than fresh seafood, including value-added forms like breaded/battered and complete dinners.

Disadvantages

Perception. Many consumers remain convinced that any fresh seafood is superior to frozen product.

Potential mishandling. To maintain quality, frozen seafood must be frozen properly initially, then kept at a constant temperature. It’s not always possible to know if you’re buying frozen seafood that’s been properly frozen and stored.

Checklist

  • Buy only good-quality frozen fish. Proper freezing can maintain quality but does not improve it.
  • Ensure proper freezing. Slow or incomplete freezing affects texture, flavor and shelf life. 
  • Most frozen seafood should be glazed with a protective coating of ice to prevent dehydration and oxidation during storage and distribution. 
  • Excessive ice crystals inside containers and wrappings indicate loss of moisture — along with flavor, texture and shelf life — the result of temperature fluctuations. 
  • Inner plastic lining (“polybag”) or plastic sheets or cellowrap surrounding a product should be of high-quality plastic and thick enough to give adequate protection. 
  • All frozen-seafood packaging should be tight and unbroken.

How Seafood Is Frozen

  • Blast freezing. Very cold air (minus 25° to minus 40°F) is circulated over a product that has been placed in trays or on racks in an enclosed space. Often the product is carried on conveyor belts through a horizon tal tunnel or vertically in an ascending spiral. Tunnel belt speed varies with product size. IQF fillets are often blast frozen, as are larger dressed fish, like salmon. 
  • Cryogenic freezing. An advanced, accelerated form of blast freezing in which individual products (e.g., shrimp, fillets) are exposed to super-cold air or, more common ly, to sprays of liquid nitrogen or carbon dioxide at temperatures of minus 150°F or colder. Cryogenic freezing offers distinct quality benefits, including a taste and texture more resembling fresh seafood.
  • Plate freezing (or contact freezing). Employs refriger ant flowing through parallel, hollow metal plates. The plates are gently squeezed together for maximum contact to produce a flat, frozen package. Fish blocks, layerpacks, shatterpacks and cellopacks are commonly frozen this way, as are blocks of shrimp and scallops. Plate-frozen products freeze in two to four hours at minus 40°F. 
  • Brine freezing. Product is immersed in a brine solution that has been mechanically chilled to 0°F. The saltwater, which remains liquid to minus 6°F, surrounds and quickly freezes odd-shaped products like crab clusters and legs. The technique can also be used to freeze packaged products. Immersion brine freezing is generally employed aboard tuna purse seiners for at-sea freezing.

How Seafood Is Thawed

Improper thawing can compromise the quality of any frozen seafood, no matter how it is frozen or packaged. Thawing methods can also affect the net weight of the product. 
Frozen fish can be defrosted in air or water or by cooking directly from the frozen state. The best results are obtained when a product is thawed slowly (for 36 hours) at temperatures just above freezing. A complete thaw, especially under forced conditions of warm air or water, may release “natural juices” that represent a portion of the product’s net weight and flavor. Always place thawing product in a drip pan to avoid build-up of melt water and drippings. 

Thawing too long or at too warm a temperature may dry out the product and invite bacterial growth. Because of the superior heat-transfer properties of water, it is a faster thawing agent than air. The cold water should be kept moving (spraying works well) while gently agitating the product. 

Whole or packaged fish may be thawed in water, but unpackaged fillets should not be defrosted in this manner because they become waterlogged and loose flavor through leaching.

The Lexicon of Frozen Seafood

Advances in freezing technology and distribution systems have led to an increase in the amount of highquality frozen seafood on the market. As demand for frozen fish and shellfish has grown, so has the vocabulary to describe these products. Here’s a sampling of the frozen lexicon.
AS (Frozen At Sea). FAS products may be frozen whole for later thawing and reprocessing on a factory ship or at a plant ashore, or they can be landed, filleted and frozen aboard the same vessel. Ground fish like pollock and cod are often filleted and frozen at sea. FAS products offer a quality advantage because they are frozen quickly after harvest.

IQF (Individually Quick-Frozen). Pieces of finfish or shellfish fast-frozen as single units, then glazed, bagged and boxed. The “quick” in IQF can refer to cryogenic methods that employ liquid nitrogen or carbon dioxide, or to blast freezing. It simply means the product was frozen in a matter of minutes or hours, not days. Products marked IQF that have been frozen in a storage freezer are incorrectly labeled, as they have been frozen too slowly and thus do not qualify as IQF.

Products frequently sold in IQF form include small, dressed whole fish like whiting, herring or smelt; peeled or shell-on shrimp, crab clusters and legs; whole fish like salmon, which are normally blast frozen, glazed and individually bagged; and scallops for retail sale.

Refreshed. Seafood that has been frozen, often in blocks, then thawed (or “slacked out”) for resale. If handled properly, the quality of this product is high, though it should be labeled “refreshed” or “previously frozen” to avoid confusion or deception. Fillets labeled “fresh” that appear dry may have been previously frozen.

Twice-frozen (also known as double-frozen). Fish or shellfish that has been frozen at sea, then thawed for reprocessing ashore and frozen a second time after processing. Microwave heating may be used to partially thaw a frozen shrimp or fish block, permitting separation of individual units still in a frozen state. Fish or shrimp blocks are often “tempered” in this manner, heated until their temperature is just below freezing, at which point portions are chipped off, then battered, breaded and immediately refrozen.

Refrozen, or “double-frozen,” products like these should offer only minimal quality loss if handled properly.


Glazed. IQF products that have been sprayed with cold water or dipped into icy water, which freezes instantly into a protective film that eliminates air pockets and reduces the likelihood of freezer burn or rancidity. Glaze should be uniform and completely cover the product. Cracks in the glaze (not simply hairline fractures) or “holidays” where the glaze is missing entirely may indicate improper glazing and the necessity to re-glaze. Re-glazing is customary and necessary during prolonged storage when the original glaze has diminished.

Beware, however, of excessive glazing and improper weight claims based on glazed weights.

How Seafood Is Frozen

  • Block. Seafood that has been placed in a form or carton and frozen in a plate freezer. Block-frozen products include shrimp, scallops, crab meat and finfish, including pollock, cod, haddock, flounder and whiting. Fish blocks, usually without skin and bone, are used as raw material for fish sticks, portions and as breaded or battered items. Shown is a 15-pound block of Alaska pollock.
  • Cellopack. The most common pack for frozen groundfish fillets, which are wrapped together, one to three fillets per ungraded packet, in cello phane or polyethylene film. Shown is a 5-pound cellopack containing six packets of Pacific cod. Since they are ungraded, cello packs are comparatively inexpensive. They can also utilize irregular cuts not appropriate for other packs.
  • Layerpack. Packs in which high-quality, carefully graded fillets are layered with edges slightly overlapping so they freeze together. The layers, typically no more than four, are separated by polyethylene sheets, allowing fish to be divided and removed (usually an entire layer at a time) while still frozen. Shown is a cross section of a 15-pound Pacific cod layerpack.
  • Shatterpack. Essentially, layerpacks that can be dropped or struck against a hard surface to break apart frozen fillets. Shatterpacked fish is wrapped in a manner that prevents the fillets from sticking together, allowing more control over the number of fillets removed at any one time. Shown is a cross-section cut from a 15-pound shatterpack of Alaska pollock.
  • IQF. Individually quick-frozen, glazed fillets (or shellfish like shrimp and scallops) packed loosely in a polyethylene-lined box. These size-graded products retain their natural shape and are very easy for the end user to handle. However, the boxes occupy more storage space than other packs and are more easily damaged. Shown is a 25-pound box of 4- to 6-ounce IQF Alaska pollock fillets.

J.J.MCDONNELL & CO.

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