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FDSC 300 > Lecture 13 - Minerals > Flashcards

Lecture 13 - Minerals Flashcards

1
Q

what are the major components of food?

A

water, ash, lipids, carb, proteins, dietary, fibers

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2
Q

what are the minor components of food?

A

minerals, vitamins, organic acids, enzymes and alcohol, nutraceuticals

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3
Q

define minerals

A

inorganic species or substances of neither animal or plant origin (doesn’t contain C, H, O or N skeleton)

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4
Q

why do we analyze for mineral content?

A
  • nutrition
  • food safety
  • food fraud
  • government regulations
  • food processing (fortification, preservative)
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5
Q

requirement for macrominerals?

A

more than 100 mg per day

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6
Q

requirement for trace minerals?

A

milli or microgram quantities per day

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7
Q

what are some macrominerals?

A

calcium, phosphorus, sodium, potassium, magnesium, chlorine, sulfur

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8
Q

what are some trace minerals

A

iron, iodine, zinc, copper, chromium, manganese, molybdenum, fluoride, selenium, silica

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9
Q

requirement for ultra trace minerals

A

still under research

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10
Q

heavy metal definition?

A

toxic to the body

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11
Q

what are some ultra trace minerals

A

vanadium, tin, nickel, arsenic, boron

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12
Q

what are some heavy metals?

A

lead, mercury, cadmium, arsenic

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13
Q

what 5 methods do we have available for food minerals?

A

1) potentiometry using ISEs
2) anodic stripping voltammetry (ASV)
3) titrimetry (EDTA complexometric and precipitation titration)
4) colorimetric
5) instrumental (atomic absorption, atomic emission)

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14
Q

what method can you use to test for hardness of water?

A
  • EDTA complexometric titration
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15
Q

describe the EDTA complexometric titration method

A
  • EDTA forms 1:1 complexes with numerous minerals
  • end points are detected using mineral chelators that have coordination constants lower than EDTA
  • different colors are produced in each of their complexed and free states
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16
Q

what indicators are used for the EDTA complexometric method? (used for Ca or Mg)

A
  • calmagite

- eriochrome black T (EBT)

17
Q

describe the color changes that happen with calmagite

A

Ca or Mg reacts with a few drops of Calmagite under basic pH (ammonia buffer makes pH 10) and turns pink

the pink complex is then titrated with EDTA complex to make a blue complex

18
Q

what’s the point of the ammonia buffer in the calmagite thing for EDTA complexometric titration

A
  • maintain basic pH
  • improve stability of EDTA-metal ion complex
  • improves sharpness of endpoint
  • makes sure pH doesn’t exceed 11 or else Ca and Mg would precipitate as hydroxides
19
Q

what is precipitation titration?

A

when at least one product of a titration reaction is an insoluble precipitate, it is referred to as precipitation titrimetry

20
Q

what methods of precipitation are there?

A
  • Mohr method

- Volhard method

21
Q

describe the Mohr method

A
  • determines Cl
  • AgNO3 reacts with Cl ions to make AgCl and NaNO3 until all Cl- ions are complexed
  • Ag reacts with K2CrO4 to make Ag2CrO4, which is orange
22
Q

describe the volhard method

A

mostly used for determining salt in high salt products

  • sample added with excess AgNO3
  • AgCl is precipitated out
  • moles of AgNO3 is left behind in the supernatant solution is measured by:
  • sample is wet ashed with HNO3
  • excess AgNO3 is back titrated with KSCN; ferric ammonium sulfate
  • end point forms a salmon-pink (ferric thiocyanate)
23
Q

what happens if you add HNO3 before adding AgNO3? (volhard method)

A

get loss of chloride by volatilization

24
Q

what are some of the chromogens used for colorimetric methods?

A
  • Alizarin 3-sulphonate for Ca determination
  • 0-cresolphthalein for Ca (under alkaline pH)
  • Ferrozine and Ferene-S for Iron
  • o-phenanthroline for Iron in meat
25
Q

how can you determine iron in meat colorimetrically ?

A

react ferrous iron with o-phenanthroline to form orange-red complex ion

26
Q

describe atomic absorption sepctroscopy

A

quantitative determination of chemical elements using the absorption of optical radiation (light) by free atoms in the gaseous state

ground state to excited

27
Q

what atomic absorption spectroscopy methods are there? which one of them is the most sensitive?

A
  • flame atomic absorption spectroscopy (FAAS)
  • graphite furnace atomic absorption spectroscopy (GFAAS)
  • cold vapor atomic absorption spectroscopy (CVAAS)

GFAAS

28
Q

describe atomic emission spectroscopy

A

based on the measurement of the electromagnetic radiation absorbed or emitted by the atoms of the measured element in a sample

excited to ground state

29
Q

what atomic emission methods are there?

A
  • flame atomic emission spectroscopy (FAES)
  • inductively coupled plasma atomic emission spectroscopy (ICP-AES)
  • inductively coupled plasma optical emission spectroscopy (ICP-OES)
30
Q

atomic spectroscopy requires that _____ of the element of interest be in the _____ state and that they be well separated in space

A

atoms, atomic

31
Q

in food, elements are present as _____ or _____

A

compounds or complexes

so they must be converted to neutral atoms before atomic absorption or emission measurements can be made

32
Q

what is atomization?

A

separating particles into individual molecules and breaking molecules into atoms

33
Q

how is atomization accomplished?

A

high temperatures in a flame or plasma

FDSC 300 (9 decks)

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