Food Biochemistry and Food Processing (2 edition)

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BLBS102-c19 BLBS102-Simpson March 21, 2012 13:33 Trim: 276mm X 219mm Printer Name: Yet to Come


346 Part 3: Meat, Poultry and Seafoods

Table 19.1.Distribution of Water, Protein, and Lipids in
100 g of Raw Edible Fish including Bones and Cartilage

Fish Water (g) Protein (g) Lipid (g)

Cod 79–81 17–19 0.6–0.8
Herring 78–80 18–20 0.5–0.7
Ling 79–80 17–19 0.6–0.8
Mackerel 63–65 17–19 15–17
Monkfish 82–84 14–16 0.3–0.5
Pilchard/sardine 66–68 19–21 8–10
Plaice 78–80 15–17 1.3–1.5
Saithe/coley 79–81 17–19 0.9–1.1
Salmon 66–68 19–21 10–12
Skate 79–81 14–16 0.3–0.5
Sole 80–82 16–18 1.4–1.6
Sprat 68–70 16–18 9–10
Trout (rainbow) 75–77 18–20 5–6
Tuna 69–71 22–24 4–5
Whiting 79–81 17–19 0.5–0.8

the fall spawning season, and to 3–4% in the winter, because of
colder water temperatures and a scarcity of food. Water replaces
the lipid depleted from muscle tissue and results in fish of poor
eating quality.
Livers of species of the Gadidae (cod) family contain 50%
lipids and are a concentrated source of vitamins A and D and
omega-3 fatty acids. Oil is commercially extracted from the liver
and purified for medicinal use and animal feed. Livers from other
species of fish (haddock, coley, ling, shark, huss, halibut, and
tuna) are also commercially processed to extract the fish oil.
In general, processing does not change the nutrient content
of fish. Drying and smoking fish reduces the water content. The
process can also reduce the lipid content of the fish if extremely
high temperatures are used. Drying also increases the concen-
tration of all nutrients on a weight basis. Sodium nitrite (usually
with sodium nitrate) that is added during the process of drying
or smoking increases the content of sodium considerably. The
salmon flesh used for smoking is lower in lipids than whole
salmon.
Breading fish adds carbohydrate and yields a final product
with a relatively lower concentrations of protein, vitamins, and
minerals than unbreaded fish.
Freezing and canning do not change the nutrient composition
of fish except for canned tuna. Most canned tuna is low in lipids,
since the lighter colored tuna is lower in fat and is preferred by
consumers over the deep brown-red-colored tuna. Tuna is also
cooked prior to canning, which removes some of the lipid.
Tables 19.1 and 19.2 compare the water, protein, and lipid
contents of different forms of fish.
The macronutrients in crustaceans and mollusks differ from
those in bony fish, since all mollusks contain carbohydrate and
lobster and scallops contain small amounts of carbohydrate.
Carbohydrate in shellfish is in the form of glycogen. The protein
content is more variable than in bony fish, and the lipid content
is comparable to that in pelagic fish (see Table 19.3; refer to
Tables 19.4 and 19.5 for comparison of micronutrients). Ranges

Table 19.2.Distribution of Water, Protein, and Lipid in
100 g of Cooked, Edible Fish

Fish Water (g) Protein (g) Lipid (g)

Haddock (smoked) 71–72 23—24 0.8–1.0
Haddock (steamed) 78–79 20—21 0.5–0.7
Herring (grilled) 63–64 20—21 11–12
Mackerel (smoked) 47–48 18—20 30–31
Mackerel (grilled) 58–59 20—21 17–18
Salmon (smoked) 64–65 25—26 4–5
Salmon (steamed) 64–65 21—22 11–12
Salmon (breaded
nuggets)

60–61 12—13 11–12

Tuna (canned in
water)

75–76 25—26 0.9–0.9

Tuna (canned in oil) 64–65 26—27 0.8–0.9
Tuna (raw, fresh, or
frozen)

70–71 23—24 4–5

are used in Tables 19.1–19.5, because data from many sources
are so variable.

Micronutrients

Micronutrients cover vitamins and minerals. Seafood is an im-
portant dietary source of vitamins A and D and the B vitamins B 6
and B 12. Although seafood is not high in thiamin or riboflavin,
the amounts are comparable to those found in beef. Fish and
shellfish have little or no vitamin C or folate.
Cod liver oil has been used to supplement diets with vitamins
A and D; one teaspoon (5 g) of cod liver oil provides 12.5μgof
vitamin D and 1500μg of vitamin A.
Mineral contributions of fish and shellfish include iodine and
selenium; a 100 g portion contains more than 50% of the dietary
reference intake (DRI) for iodine (DRI 5-150μg/day) and se-
lenium (DRI 5-55μg/day), respectively. Generally, meat, eggs,
and dairy products are poor sources of iodine and selenium.
Iron and zinc are found in moderate amounts in most seafood.
Clams and oysters are concentrated sources of zinc, with 24
and 91 mg/100 g serving, respectively, compared with a DRI of
15 mg/day. Seafood, similar to other dietary protein sources, is
also an excellent source of potassium. Fresh seafood contains
varying amounts of sodium, from a low of 31 mg/100 g of trout
to a high of 856 mg/100 g of crab. Sodium is also added during
canning and smoking fish and other seafood. In general, seafood
is a poor source of calcium, except for whole canned salmon
and sardines: when their bones are included, they will provide
200–400 mg calcium/100 g portion.

Other Components

Seafood, like other animal products, contains cholesterol. The
cholesterol content in fish and mollusks ranges from 40 to
100 mg/100 g portion and is lower than in other meat such as
beef, pork, and chicken. However, the shellfish, shrimp, and
prawns are quite high in cholesterol—195 mg /100 g portion
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