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Food Analysis > Lecture 15 - Minor Components > Flashcards

Lecture 15 - Minor Components Flashcards

1
Q

what is the definition of nutraceuticals

A

a product isolated or purified from foods that are generally sold in medicinal forms not associated with food

demonstates to have physiological benefits or provides protection against chronic disease

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2
Q

what is a nutraceutical found in grapes?

cumin?

A

grapes: reservratrol
cumin: curcumin

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3
Q

what are phenolic compounds

A

polyphenols are substances which consists of an aromatic ring linked to one or more OH groups, including functional derivatives (ester,s methyl ethers, glycosides, etc…)

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4
Q

how many polyphenolics and flavonoids have been identified?

A

8000 polyphenolics and 4000 flavonoids

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5
Q

how are phenolic compounds classified?

A
  1. phenolic acids
  2. flavonoids
  3. tannins
  4. stillbenes and lignans
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6
Q

what are types of flavonoids?

A 
flavonols
flavones
flavanols
flavanones
isoflavones
proanthocyanidins
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7
Q

what are types of phenolic acids?

A

hydroxycinnamic (eg p-coumaric, caffeic, ferulic and sinapic acids)

hydroxybenzoic acids (eg gallic acid and protocatechuic acid)

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8
Q

are hydroxycinnamic or hydroxybenzoic acids more prevalent in food?

A

hydroxycinnamic are more prevalent

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9
Q

what is the importance of phenolic compounds in general?

A
  • anti-aging properties due to antioxidants

- reduces risk of coronary heart diseases and cancer

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10
Q

what causes the antioxidant activity of phenolic compounds?

A

due to reactivity of the phenol moiety (OH substituent on the aromatic ring)

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11
Q

importance of phenolics in the food industry?

A
  • phenolics have effects on fruit maturation (they can be converted to brown pigments and cause loss of nutritional and functional qualities in foods)
  • polyphenols cause enzyme catalyse discoloration in cheeses (causes undesirable flavors)
  • inhibits lipid oxidation in some foods (eg raw and cooked meat, poultry and fish)
  • can bind proteins ,CHOs and reduce digestibility
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12
Q

what are 4 ways to determine phenolic compounds

A
  1. sepctrophotometric methods (folin-ciocalteu assay)
  2. chromatographic techniques
  3. near infrared (NIR FT-IR)
  4. Mass spectroscopy (MS)
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13
Q

what are types of chromatographic techniques used to determine phenolic compounds?

A
  1. high performance liquid chromatography (HPLC)
  2. HSCCC (high counter current chromatography)
  3. supercritical fluid chromatography (SFC)
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14
Q

describe the folin-ciocalteu assay

A
  • type of spectrophotometric method
  • polyphenols reacts with redox reagents (folin-ciocalteu reagent: phosphomolybdic and phosphotungstic acid) to form a blue complex that can be measured
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15
Q

what does the folin ciocalteu reagent consist of?

A

phosphomolybdic and phosphotungstic acid

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16
Q

what color is formed when phenolic compounds react with FC reagent?

A

blue

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17
Q

what is the procedure of the Folin ciocalteu assay?

A
  1. place sample in flask
  2. add water
  3. add FC reagent
  4. incubate at room temp
  5. add sodium carbonate (Na2CO3)
  6. add water and incubate
  7. measure blue solution at 765 nm
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18
Q

what is an essential step before using chromatographic techniques to determine phenolic compounds?

A

need to extract phenolic compounds before using the chromatographic techniques

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19
Q

describe liquid-liquid extraction for phenolic compound analysis?

A

a mass transfer operation in which a liquid solution (the feed) initially containing one or more solutes is thoroughly mixed with an immiscible or nearly immiscible liquid (solvent

the solvent exhibits selectivity towards one or more of the components in the feed and has different density

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20
Q

what are the 3 types of extraction methods to use before applying chromatographic techniques?

A
  1. liquid liquid extraction
  2. solid-liquid (leaching)
  3. supercritical fluid extraction (SFE)
21
Q

what is the leaching process also called?

A

solid liquid extraction

22
Q

describe solid-liquid extraction

A
  • mass transport phenomenon where solids contained in a solid matrix migrates into solvent brought into contact with the matrix
  • can be used to recover important food components: sucrose in cane, lipids from oil seeds, etc…
23
Q

what can enhance mass transport phenomena?

A

concentration gradients
diffusion coefficients
boundary layer

24
Q

describe SFE extraction

what is the most utilized fluid?

A
  • supercritical fluid extraction
  • based on the fact that the solvent changes its properties rapidly with only slight variation of pressure when close to the critical point
  • most utilized fluid is supercritical carbon dioxide (SC-CO2)
25
Q

reasons to add color (pigments and colorants) to food?

A
  1. to replace color lost during processing
  2. to enhance color already present
  3. to minimize batch to batch variations
  4. to color uncolored food
26
Q

categories of food colors?

A
  1. natural colors
  2. nautre-identical colors
  3. synthetic colors
  4. inorganic colors
27
Q

examples of natural pigments?

A

anthocyanins:

  • flavonoids compounds
  • range: orange, red, blue and purple

carotenoids:

  • lipid soluble
  • range: yellow, orange, red
  • eg carotenes, lycopene, lutein, annatoo

chlorophyll

  • lipid soluble
  • green pigment
28
Q

describe the chemistry of autumn colors

A

green

  • chlorophyll A
  • requires warm temp and sunlight

yellow

  • carotenoids and flavonoids
  • xanthophylls (subclass ofcarotenoids) are responsible for yellow of leaves
  • always present in leaves, but appears when chlorophyll is degraded

orange

  • carotenoids
  • starts degrading at same time as chlorophyll, but at a slower rate

red

  • anthocyanins and carotenoids
  • synthesis starts at autumn, when sugar concentration increases, sunlight initiates anthocyanin production
29
Q

describe polarity of anthocyanins

A

polar

soluble in solvents, eg alcohol, acetone, dimethyl sulfoxide, water

30
Q

3 steps of anthocyanin analysis?

A
  1. extraction
  2. purification
  3. measurement
31
Q

describe extraction of anthocyanins

A
  • acetone extraction and chloroform partition
  • aqueous two phase system (ATPs)
  • acetone extracts anthocyanins from plant material
  • then chloroform partitioning further isolates and purifies the pigment. This results in phase separation between aqueous portion (with the anthocyanin, phenolics, sugars, organic acids) and the bulk phase (contains the immiscible organic solvents, lipids, carotenoids, etc…)
32
Q

in analysis of anthocyanins, what is the role of acetone?

A

extracts anthocyanin from plant material

chloroform is used after

33
Q

in analysis of anthocyanins, what is the role of chloroform?

A

isolates and purifies the pigment

results in phase separation between aqueous portion (with the anthocyanin, phenolics, sugars, organic acids) and the bulk phase (contains the immiscible organic solvents, lipids, carotenoids, etc…)

34
Q

procedure of anthocyanin extraction?

A
  1. mix powdered plant material with acetone
  2. separate anthocyanin extract (filtrate) from insoluble plant material by a filter paper
  3. re-extract plant material with acetone until a clear solution is obtained
  4. transfer filtrate to a funnel
  5. add chloroform and mix
  6. store sample until a clear partition between two phases is obtained
35
Q

describe the purification step in anthocyanin analysis

A
  1. mix sample with water = washes out sugars and acids
  2. add ethyl acetate = washes out phenolics
  3. add methanol = washes out anthocyanins
36
Q

describe the measurement step of anthocyanin analysis using UV visible spectroscopy (pH differential method)

what reaction occurs?

A
  • based on structural transformation of the anthocyanin chromophore as the pH changes. The colors can be measured spectoscopically
  • it is a method used for rapid measurement of the total anthocyanins, even in presence of polymerized degraded pigments and other interfering compounds

reaction:

  1. blue quinonoidal base at pH 7
  2. orange flavylium cation (oxonium form) at pH 1
  3. colorless carbinol pseudobase (hemiketal form) at pH 4.5
  4. colorless chalcone at pH 4.5
37
Q

in the pH differential method, what compound is at pH 1?

A

orange flavylium cation (oxonium form)

38
Q

in the pH differential method, what compound is at pH 7?

A

blue quinoidal base

39
Q

in the pH differential method, what compounds s are at pH 4.5?

A

colorless chalcone

and carbinol pseudobase (hemiketal form)

40
Q

what do the choices of analytic methods for the detection and determination of food hazards must take into account?

A

the complexity of the food matrix and the characteristics of the analyte (ie. polarity, hydrophobicity, volatility, thermal stability, chemical reactivity)

41
Q

what are types of hazardous contaminants?

A

mycotoxins

pesticides

toxic compounds derived from lipids

toxins formed as a result of cooking or processing of food

naturally occurring hazards in foods

42
Q

what are examples of pesticides?

A

Benzimidazoles,
CarbamateInsecticides, Halogenated Hydrocabon Pesticides, Organophosphate Insecticides, PyrethrinInsecticides and Triazine Herbicide

43
Q

examples of toxic compounds derived from lipids?

A

malondialdehyde(MDA), and 4-hydroxyalkenals (4-HAEs), malvalicacid, and sterculicacid

44
Q

examples of toxinds formed as a result of cooking or processing of food?

A

N-Nitrosamines, Polycyclic aromatic hydrocarbon

45
Q

examples of naturally occurring hazards in foods?

A

Saxitoxin, Okadaicacid, Brevitoxins, Ciguatoxin, Tetrodotoxin, Safrole, Gossypol

46
Q

how are mycotoxins produced?

A

when molds (filamentous fungi) develop on food commodities and produces toxins, known as mycotoxins

47
Q

what are main proucers of mycotoxins?

A

fungal species belonging to the genera aspergillus, fusarium and penicillin

48
Q

how much of the world’s total crops per year are affected with unacceptable levels of mycotoxins?

A

25%

49
Q

what are the major classes of mycotoxins that have impacts on human health?

A
  1. aflatoxins (B1, B2, M1, M2, G1 and G2)
  2. ochratoxins (ochratoxin A, OTA)
  3. Trichothecenes (deoxynivalenol (DON), T2, HT2)
  4. fumonisins (FBs: FB1, FB2, FB3, etc…) and patulin (found in apple products)
  5. Zearalenone (ZEA)

Food Analysis (17 decks)

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