Lecture 15 - Minor Components Flashcards

1
Q

what are minor components of food?

A
  • nutraceuticals

- pigments

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2
Q

what’s nutraceutical?

A

product isolated or purified from foods generally sold in medicinal forms not usually associated with food. also shows physiological benefit against chronic disease.

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3
Q

name some nutraceuticals

A
  • resveratrol
  • curcumin
  • Epigallocatechin gallate (EGCG)
  • Epicatechin gallate (ECG)
  • Epigallocatechin (EGC)
  • phenolic compounds
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4
Q

what are phenolic compounds?

A

consist of an aromatic ring linked to one or more hydroxyl groups. includes functional derivatives (esters, methyl esters, glycosides, etc)

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5
Q

how many phenolics are there out there?

A

over 8000, and counting

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6
Q

into what classes can phenolic compounds be classified?

A

1) phenolic acids
2) flavonoids
3) tannins
4) stilbenes & lignans

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7
Q

name some phenolic acids in foods

A
hydroxycinnamic acids
- p-coumaric
- caffeic
- ferulic
- sinapic
hydroxybenzoic acids
- gallic
- protocatechuic
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8
Q

what effect do phenolic compounds have?

A
positive:
- free radical scavengers (anti aging)
- reduce risk of coronary heart disease
- reduce some cancer types
- color
- lipid retention
negative
- undesired changes in color (enzymatic browning)
- protein and CHO binding, reducing digestibility
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9
Q

what kinds of methods can we use to determine phenols?

A
  • spectrophotometric
  • chromatographic
  • Near Infrared
  • Mass Spec
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10
Q

what spectrophotometric method is used for phenolic determination?

A

Folin-Ciocalteu assay

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11
Q

describe the Folin-Ciocalteu assay

A

based on the chemical reduction of the FC reagent by phenolic compounds, making a blue complex.

measure at 765 nm

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12
Q

what are the steps used in the Folin-Ciocalteu assay?

A
  • gallic acid calibration standard
  • FC reagent (phosphomolybdic/phosphotungstic acid)
  • sodium carbonate
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13
Q

what kinds of chromatographic methods are there for phenolic determination?

A
  • HPLC
  • HSCCC (high counter current chromatography)
  • SFC (supercritical fluid chromatography)
  • PC
  • TLC
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14
Q

true or false: you have to extract phenolic compounds before using chromatographic techniques

A

true

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15
Q

what is HSCCC?

A

high counter current chromatography

separation between 2 liquid phases by use of centrifugal or counter current during mixing of 2 liquid phases

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16
Q

what methods of extracting phenolics are there?

A
  • liquid liquid extraction
  • solid-liquid extraction (leaching)
  • supercritical fluid extraction
17
Q

describe liquid liquid extraction

A
  • mass transfer operation
  • liquid solution initially containing one or more solutes is thoroughly mixed w/immiscible liquid
  • solvent exhibits preferential affinity toward one or more the components
  • solvent containing the compound of interest is separated w/separating funnel
18
Q

describe solid-liquid extraction

A
  • mass transport

- compound contained in a solid matrix migrate into solvent

19
Q

what can enhance the mass transport phenomena during solid-liquid extraction?

A
  • changes in concentration gradients
  • diffusion coefficients
  • boundary layer
20
Q

what can solid-liquid extraction be used for?

A

recover food components

  • sucrose in cane or beets
  • lipids from oil seeds
  • proteins in oilseed meals
  • polyphenolic compounds from plants, fruits and veggies
21
Q

describe supercritical fluid extraction

A

close to its critical point, a solvent changes its properties rapidly with only slight variation in pressure

22
Q

what is the most utilized fluid for SFE?

A

supercritical carbon dioxide

23
Q

why do we analyze for pigments in food?

A
  • color impacts first impressions of food
  • quality indicator
  • safety indicator
24
Q

what are some reasons colors are added to food? (4)

A
  • replace lost color
  • enhance color already present
  • minimize batch-to-batch variations
  • color otherwise uncolored foods
25
food colors are divided into what 4 categories
1) natural colors 2) nature-identical colors 3) synthetic colors 4) inorganic colors
26
give examples of natural pigments
- anthocyanins - carotenoids - chlorophyll
27
how can you analyze for anthocyanins?
anthocyanins are polar, so you can extract the using polar solvents (alcohols, acetone, dimethyl sulfoxide, and water)
28
choice of extraction method should maximize _____ _____ with a minimal amount of ______. method should also minimize _____ or alteration of natural state
maximize pigment recovery minimal amount of adjuncts degradation
29
describe the analysis of anthocyanins
acetone extraction and chloroform partition of anthocyanins - acetone extracts anthocyanins - chloroform partitioning further isolates and partially purifies - adding chloroform results in phase separation - aq = anthocyanin, phenolics, sugars, organic acids, others - bulk phase = immiscible organic solvents, lipids, carotenoids, chlorophyll pigments, and others)
30
give the steps of extracting anthocyanins
1) mix powdered plant material w/acetone 2) filter to separate anthocyanin extract and insoluble plant material 3) re extract plant material with acetone until clear/faintly colored solution is obtained 4) add chloroform in separatory funnel 5) store for a while until clear partition is obtained 6) purify using column chromatography
31
what kind of columns can are used to purify anthocyanin samples?
- water and HCl (separates sugars/acids) - ethyl acetate (separates phenolics) - methanol (elutes the anthocyanins)
32
what method can be used to analyze for anthocyanins?
3-measure step: 1-UV-Vis Spectroscopy based on structural transformation of anthocyanin chromophore as a function of pH, measured w/optical spec
33
what is the 1-UV-Vis spectroscopy method also known as?
ph-differential method
34
is the pH-differential method fast?
yep
35
anthocyanins undergo (reversible/irreversible) structural transformation with change in pH
reversible
36
colored oxonium form predominates at pH ___
1.0
37
colorless hemiketal form predominates at pH ____
4.5