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Fish and Shellfish Flashcards

1
Q

What is seafood?

A

aquatic animals for human consumption

true fish + shellfish

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2
Q

What are the commonly marketed fish products? (6)

A 
Fresh
Frozen
Smoked/salted/marinated
Canned
Fish Meal
Fish Oil
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3
Q

The top fish producing country is:

A

China

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4
Q

What are the various animal types harvested for seafood?

A 
vertebrates:
- bony fish
- cartilagenous fish (shark, skate)
invertebrates:
- mollusc
- crustacean
- echinoderms
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5
Q

What are the flavor classifications of fish? give some examples

A

Mild: Cod, Halibut, Porgie
Medium: Shrimp, Lobster, Skate
Strong: Salmon, Mackerel, Sardines

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6
Q

What are the factors that affect fish composition? (8)

A
  • species
  • diet
  • season
  • age
  • sex
  • habitat
  • population density
  • migratory or spawning behaviour
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7
Q

Most fish sold as food is in ____ form, followed by _____.

A

frozen (24%); fresh (22%)

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8
Q

Wild harvest of fish was increasing, but now has stabilized around ___. Why?

What source of fish in increasing?

A

95 tonnes

  • Regulations (government limit)
  • Depletion of stocks (overfished, few left)

Aquaculture (farmed fish) is increasing

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9
Q

What are some non-food uses of fish? (5)

A 
Fertilizer
Feed
Supplements
Gelatin (glue)
Cosmetics
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10
Q

Name the fins on a teleost fish:

A

on back: Dorsal, Adipose (near tail)
Tail: Caudal
Belly: Pectoral (front), Pelvic, Anal

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11
Q

How does fat distribution differ in fatty and lean fish? What types of lipid predominate?

A

fatty: fat throughout flesh
lean: fat accumulates in liver/gut

mostly TG, also PL in skin and membranes

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12
Q

fish is about ___% protein, which is comparable to ____.

A

16-21%

beef

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13
Q

What component shows the most variation in fish? What other component will also vary, and what causes these variations?

A

Lipids, also protein
spawning/migration -> use energy, lower lipid/protein
increase in period of heavy feeding

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14
Q

Describe the 2 layers of fish skin:

A 
outer layer: epidermis
- high moisture
- glands make mucus (MUCOPOLYSACCARIDES)
inner layer: dermis
- scales
- conn tissue fibres
- pigment cells (GUANOPHORES)
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15
Q

The main sugars of mucopolysaccharides that form the fish slime layer are: (2)

A

glucosamine, galactosamine

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16
Q

Fish oil is an excellent source of ____ PUFAs, but what problem does this cause?

A 
omega 3 (good for health!)
prone to oxidative rancidity
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17
Q

What is the main cause for the rapid bacterial decay of fish?

A

The microflora present on scales/skin, resistant to low temperatures

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18
Q

Name the 3 protein types in fish, and their proportions.

A

Sarcoplasmic (dissolved) - 20-30%
Myofibrillar (muscle, salt-soluble): 65-75%
Stromal (insoluble) : 3-10%

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19
Q

actin, myosin, and troponin are all ____ proteins, while collagen is a ____ protein.

A

myofibrillar

stromal

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20
Q

how do the proportions of fish protein types compare to that in mammals?
How does this affect the fish meat?

A

Less stromal: don’t need as much connective tissue since water can support weight

More myofibrillar: need strong muscle for swimming

sarcoplasmic stays the same (enzymes, etc)

fish is more tender than meat, since less sarcoplasmic

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21
Q

What type of protein is Mb?

A

sarcoplasmic

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22
Q

How do fish myofibrillar proteins compare to mammalian counterparts?

A

more myofibrillar, but individual proteins in same proportion
More easily denatured by heat
Fast hydrolysis
(easy digestibility)

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23
Q

True/False: the sarcoplasmic protein proportions and types remain fairly constant among all fish.

A

False: different patterns can be seen, and used to identify fish

24
Q

What sarcoplasmic fish protein is different from the mammal version? This protein is concentrated in ______.

A

Mb - fish has cysteine, mammal does not

concentrated in dark muscle

25
Fish protein generally has higher levels of what AAs, compared to mammals? This means that it would pair well with:
lysine, cysteine, methionine | cereals (low in those AAs)
26
___, a very basic non-protein AA, is found in fish and has antimicrobial properties
protamine
27
The main connective tissue proteins in fish are:
collagen (90%), elastin
28
How does the final meat yield from fish compare to mammals?
lower yield after removal of head, guts, tail, etc (lose up to 50%) mollusc/crustacea lose even more (over 50%) but less losses during cooking
29
True/False: fish contain all the essential AAs.
True (like all animal protein)
30
What are the major NPNs found in fish? (6)
N containing extractives: - volatile bases (TMAO, NH3) - urea (cartilagenous fish) - nucleotides/purines - free AA - creatine
31
Fish are a good source of what vitamins and minerals?
vitamins: B (multiple), D and A (fatty fish) minerals: Na, K, Mg, Fe, I (saltwater), Se, Cu, Ca, P
32
What are some non protein AA found in fish? (4)
betaine, carnosine, anserine, protamine
33
TMAO is naturally present in fish for what purpose? What happens after harvest?
trimethylamineoxide - help fish stay afloat (osmolyte) TMAO reduced (lose H2) -> TMA -> (dehydrogenase) -> DMA + formaldehyde TMA has fishy odor (bad) formaldehyde will cross link proteins -> tougher texture
34
_____ fish contain some urea content
cartilagenous
35
What are the various nucleotides? (5)
ATP, CTP, UTP, TTP, GTP
36
breakdown of ___ yields IMP, which is (good/bad). Why?
ATP; good (enhance flavor, indicates freshness)
37
___ is produced from AA catabolism, its presence in fish indicates poor quality
urea
38
How would continued breakdown of ATP produce unwanted compounds? Describe the process
ATP -> ADP -> AMP -> adenosine + IMP (good, enhance flavor) | IMP -> hypoxanthine -> xanthin -> uric acid/urea hypoxanthine, xanthin, urea will cause off taste, quality loss
39
What are the carbohydrate sources in fish? (2)
glycogen in muscle | polysaccharides in slime layer
40
Fish contains (more/less) glycogen than mammals.
less; need lot of energy for swimming so less is stored
41
What is the "lateral line"
horizontal row of scales down fish body - can use to sense changes in surroundings/movement
42
Describe the process of bringing wild fish to market (8)
1. catch 2. hold (store live in tanks, since long time at sea) (can use tranquilizer to slow - Aqui-S) 3. sort (remove bycatch, too small fish) 4. bleed/gut - remove head/guts/blood 5. clean/wash - remove pigments and gut residue (contamination) 6. ice/chill 7. storage 8. market
43
What are the grades of fish? What are some factors it is based on, and what 2 factors do not affect grade?
Premium, A, B, C color of eyes/gills, state of fins/skin/body, odor, if it has been bled/chilled does not depend on flesh color, or skin color (varies with species and feed)
44
What problems can occur with evisceration? (3)
blood pigments will discolor fish gut bacteria cause contamination proteases/lipases cause degradation
45
What are some uses for undesirable fish? (2)
``` Mild fish (pollock, carcasses, etc) -> surimi strong fish (mackerel, herring) -> fish oil ```
46
What is surimi? How is surimi produced?
nutrient dense fish paste take mild fish -> gut/bleed/clean -> debone -> leach -> strain -> mix with CRYOPROTECTANTS (preserve texture) -> pack in frozen storage
47
How is fish oil obtained?
cook fatty fish -> press to remove liquid -> separate liquor into water and CRUDE OIL -> water wash + C to remove odors/pigment -> fish oil
48
What is the lipid composition of fish oil? What are its uses (5)?
PUFAs: 40% MUFAs: 30% SFAs: 30% ``` health: PUFAs prevent cardiovasc disease, important for growing brain cosmetics fuel plant protective coatings paint ```
49
What are two compounds in crustacean waste that can be repurposed?
carotenoproteins - coloring - as additive or for salmon feed | chitosan/chitin - films, plastics, thickeners, etc
50
How is chitosan obtained?
crush -> demineralize (chelator) -> proteolysis (protease) -> centrifuge dry the residue: and repeat previous steps to purify -> decolorize with acetone, HClO2, or peroxide -> CHITIN -> remove acetyl group -> CHITOSAN
51
Fish gelatin is in ___ form, so it is easy to work with, and acts as a ____ or _____. What are some non food uses?
liquid; stabilizer; thickener | can use for pharmaceuticals, glue, films
52
Describe the process of fish skin gelatin production
remove oil for other uses, then dry with mild heat to not damage protein solvent extraction to completely defat Use NaOH and Trypsin to destroy non-collagen protein Use chelator (citric acid) to remove minerals hydrolyze collagen with pepsin or other protease gelatin
53
Describe the process of fish skin gelatin production
remove oil for other uses, then dry with mild heat to not damage protein solvent extraction to completely defat Use NaOH and Trypsin to destroy non-collagen protein Use chelator (citric acid) to remove minerals hydrolyze collagen with pepsin or other protease gelatin
54
How are carotenoproteins extracted from crustacean shells?
take supernatant (liquid) after chitin removal, then dry
55
What is the difference between chitosan and chitin?
Chitin has acetyl group, insoluble white powder. | convert to chitosan to make soluble in dilute mineral acid.

food commodities (5 decks)

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