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FDSC 319 > Fish pt. 3 > Flashcards

Fish pt. 3 Flashcards

1
Q

list some components of fish that can cause adverse health effects

A
  • heavy metals
  • allergens
  • biotoxins
  • parasites
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2
Q

describe the effect of heavy metals from fish

A 
Cd, As, Hg, Pb
found to elicit health disorders including:
- neurological
- kidney
- headaches
- fatigue
- coughing
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3
Q

what is the major allergen in fish

A

parvalbumin

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4
Q

what are some examples of biotoxins from fish

A
  • scombroid: histamines from scombroid fish species (tuna, mackerel, herring)
  • tetrodotoxin (pufferfish)
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5
Q

give an example of a parasite found in fish flesh

A

anisakis

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6
Q

list some non-protein nitrogenous compounds

A
  • free amino acids
  • trimethyl amine oxides
  • betaine
  • carnosine
  • anserine
  • creatine
  • urea
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7
Q

what is TMAO?

A

trimethyl amine oxides: maintains osmotic balance in aquatic animals

  • protects biological molecules from changes in environmental stresses like temperature and pressure
  • assists animal in floating in aqueous environment
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8
Q

what are the breakdown products of TMAO?

A

TMA, which breaks down into DMA, and FA

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9
Q

expand TMA

A

trimethyl amine

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10
Q

expand DMA

A

dimethyl amine

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11
Q

expand FA

A

formaldehyde

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12
Q

what’s responsible for the fishy odors associated with bad quality fish?

A

TMA and DMA

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13
Q

what’s the role of FA in fish?

A

causes cross linkages between proteins in fish flesh which makes the texutre toughen

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14
Q

what is betaine?

A
  • NPN
  • osmolyte
  • net neutral charge
  • functions similar to TMAO
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15
Q

what is carnosine?

A
  • dipeptide comprised of B-alanine and histidine

= acts as an antioxidant

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16
Q

what is anserine?

A
  • dipeptide comprised of B-alanine and methyl histidine
  • acts as an antioxidant
  • more potent antioxidant than carnosine
17
Q

why does having a methyl on the histidine make it a better radical scavenger?

A

inductive forces imparted by the methyl group increase the draw of electrons toward the molecule

18
Q

what is creatine?

A
  • NPN
  • glycine + arginine
  • can be converted to creatine-phosphate by dephosphorylating ATP to ADP
  • serves as an energy reservoir
19
Q

what is urea?

A
  • NPN
  • formed from the oxidation of amino acids, proteins, and breakdown of nucleic acid
  • osmolyte (helps w/floatation)
  • offers an unpleasant flavor except for in a few cultures
20
Q

what are the steps of fish processing/handling?

A

1) catching
2) holding
3) sorting/grading
4) bleeding and gutting/evisceration
5) washing
6) icing/chilling
7) packaging and storage
8) distribution to markets

21
Q

how are fish caught?

A

usually on large boats where they are continually caught until the boat is at capacity

22
Q

what factors may influence the end quality of a fish?

A
  • catching gear/technique
  • method of holding the fish
  • whether or not you remove the guts/blood
  • level of cleanliness
  • pressure of jets used to wash fish
23
Q

why are fish gutted?

A

avoid “belly burst”: guts have a lot of digestive enzymes that can remain active and act on the stomach and intestine and degrade them and cause the stomach to burst, releasing a slew of microorganisms that can contaminate the meat

24
Q

why is fish bled?

A

prevent discolorations

25
Q

why is fish washed?

A

remove residues from the gutting/bleeding step

26
Q

describe how fish are iced/chilled

A

alternate layers of flakes of ice and fish in insulated containers so there is not too much pressure on the fish

27
Q

how is fish quality assessed?

A

breakdown of ATP after the animal dies

28
Q

describe the breakdown products of ATP

A

ATP –> ADP –> AMP

29
Q

what are the breakdown products of AMP?

A
  • adenosine by losing another P
  • inosine-monophosphate (IMP) by losing NH3
  • IMP –> inosine by losing P
  • inosine –> hypoxanthine –> xanthine –> uric acid
30
Q

what molecule is responsible for the fresh, sweet taste that we associate with good quality fish?

A

IMP

31
Q

what molecules are responsible for the unpleasant flavors that denotes fish as low quality?

A

Inosine, hypoxanthine

32
Q

physically draw all the breakdown products of ATP as it pertains to fish quality

A

:)

33
Q

what is used as an index of freshness for fish?

A

K value

K = ([ino]+[Hx])/([IMP]+[ino]+[Hx])

34
Q

a higher K value indicates (higher/poorer) quality fish

A

poorer

FDSC 319 (13 decks)

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