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FDSC300 > 11-CHO > Flashcards

11-CHO Flashcards

1
Q

The Components included in a “Proximate Analysis” approach are?

A

(1) Moisture
(2) Ash
(3) Protein
(4) Fibre
(5) Fat

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2
Q

____ is generally not included? why?

A

CHO, because it exists in different forms.

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3
Q

how does %cho measured?

A

%CHO= 100- (%H2O+ %Ash+ %Protein+ %Fibre+ %Fat).

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4
Q

N-containing is the?

A

crude protein

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5
Q

ash is organic/inorganic?

A

inorganic

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6
Q

what is the function of digestible cho?

A

metabolic energy

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7
Q

what is the function of non-digestible cho?

A

•bulkiness,body,
viscosity,stability to emulsions
and foams,
• water-holding capacity,
• stability to freezing and thawing,
• browning (including generation of flavors and
aromas),
• textures (from crispness to smooth, soft gels),
• lower water activity and thereby inhibit
microbial growth

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8
Q

according to WHO/FAO, CHO is classified on _____? also known as ____?

A 
molecular size (degree of polymerization (DP))
 Sugars (DP 1–2)
 Oligosaccharides(DP 3–9)
 Polysaccharides (DP >9)
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9
Q

DP1-2

A

sugar

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10
Q

oligosaccharide DP?

A

3-9

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11
Q

polysaccharide DP?

A

> 9

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12
Q

According to international nomenclature rules, Oligosaccharide as carbohydrate
composed of ___ to ___ _____ units
Polysaccharides usually contain ____ to ____ or more _______

A

2-20 sugar units

30-60,000 monosaccharide

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13
Q

give ex of monosaccharides

A

glucose, Fructose, galactose, arabinose and xylose ).

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14
Q

give ex of oligosaccharides

A

e.g disaccharides such as sucrose and lactose, and trisaccharides such as raffinose

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15
Q

what are polysaccharides,, ex.

A

Polysaccharides are polymers of monosaccharides (>10).

  1. 1-Homopolysaccharides (e.g. starch, cellulose, glycogen formed from only glucose).
  2. 2-Heteropolysaccharides (e.g. pectin, hemicellulose and gums).
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16
Q

is arabinose mono, oligo or poly?

A

mono

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17
Q

is raffinose mono, oligo or poly?

A

oilgo, trisaccharides

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18
Q

is xylose mono, oligo or poly?

A

mono

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19
Q

what is homopolysaccharide?

A

formed from only glucose

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20
Q

ex of homopolysaccharide?

A

cellulose, glycogen, starch

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21
Q

ex of heterpolysaccharide?

A

pectin, hemicellulose, gums

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22
Q

Carbohydrates in foods may be present as?

A

1- Unbound molecules
2- physically associated to other molecules (starch,
granules)
3- chemically bound to other molecules (glycolipids,
glycoproteins)

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23
Q

starch is _____ associated to other molecules?

A

physically

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24
Q

glycolipids is _____ associated to other molecules?

A

chemically

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25
Q

glycoprotein is _____ associated to other molecules?

A

chemically

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26
Q

granules is _____ associated to other molecules?

A

physically

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27
Q

why determine food cho?

A

Nutritional Labeling Detection of Adulteration
Food Quality
food processing

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28
Q

what is food quality?

A

physicochemical properties of foods such as sweetness, appearance, stability and texture depend on the type and concentration of carbohydrates present.

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29
Q

the type and concentration of carbohydrates that are present affect?

A
  • –the efficiency of many food processing operations

- –physicochemical properties of foods such as sweetness, appearance, stability and texture

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30
Q

The carbohydrate content of a food can be determined by calculating the _________________have been measured?

A

calculating the percent remaining after all the other components
% Carbohydrates = 100 - ( %H2O+ %protein + %lipid+ %Ash + %Fiber).

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31
Q

This method can lead to _________ due to _____________, and so it is better to ________ measure the carbohydrate content for accurate measurements.

A

erroneous result

experimental error in any of the other methods, directly

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32
Q

how does the sample prepared?

A
  1. raw material, dry get water and dehydrated material
  2. dehydrated material 1. grind, 2. extracted with 19:1 CHCl3-MeOH, get lipids and lipid-soluble components , residue
  3. residue: extract with 80% ethanol get ion exchange, residue
  4. ion exchange , get mono and disaccharide
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33
Q

list the methods to analysis CHO

A
  1. chemical methods
  2. physical
  3. enzymatic
  4. instrumental methods
  5. immunoassays
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34
Q

what does chemical methods have?

A

Colorimetric methods, Titration methods, Gravimetric methods.

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35
Q

what does physical methods have?

A

Polarimetry, Refractometery,

Density

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36
Q

what does instrumental methods have?

A

chromatography
NMR
electrophoresis
IR

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37
Q

what does NMR belong to?

A

instrumental

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38
Q

what does polarimetry belong to?

A

physical

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39
Q

what does gravimetric belong to?

A

chemical

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40
Q

what does colorimetric belong to?

A

chemical

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41
Q

what does refractometery belong to?

A

physical

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42
Q

what does chromatography belong to?

A

instrumental

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43
Q

what does electrophoresis belong to?

A

instrumental

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44
Q

what does density belong to?

A

physical

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45
Q

what does titration belong to?

A

chemical

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46
Q

what does IR belong to?

A

instrumental

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47
Q

what does colorimetric methods have?

A

Phenol-Sulfuric Acid Method,

Anthrone Method, Somogyi-Nelson Method

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48
Q

what does titration method have?

A

lane-enon method

49
Q

what does gravimetric method have?

A

munson-walker method

50
Q

describe phenol-sulfuric acid method? what does it used for

A

used for total cho

sample have cho, heat add H2SO4, get furan component, condensation with phenol, get colored compounds, yellow-gold color, measure by spectrophotometer at 490nm

51
Q

what does phenol-sulfuric acid belongs to ?

A

colorimetric, chemical

52
Q

what does lane-enon belongs to ?

A

titration, chemical

53
Q

what does munson-walker belongs to ?

A

gravimetric, chemical

54
Q

what does anthrone belongs to ?

A

colorimetric, chemical

55
Q

what does somogyi-nelson belongs to ?

A

colorimetric, chemical

56
Q

what is the adv for phenol-sulfuric acid method?

A

Simple, sensitive, accurate, specific for carbohydrates.

57
Q

what kind of reaction is not involved in phenol sulfuric acid?

A

stoichiometric reaction

58
Q

the extent of reaction is a function of the ________of the sugar.

  • If different sugars found in the sample, _______ is used to prepare the standard curve.
  • _____or any other _______ _______produce a _______ result
A

the extent of reaction is a function of the structure of the sugar.

  • If different sugars found in the sample, glucose is used to prepare the standard curve.
  • Sorbitol or any other sugar alcohol (alditol, polyol, polyhydroxyalcohol) does not produce a positive result
59
Q

what is the basic principle of anthrone method?

A

Carbohydrates are dehydrated by strong acids to produce (furan component).

60
Q

what does anthrone methods used for?

A

quantification total cho

61
Q

Furan components react with ______ reagent to yield a _______ color solution.
- Absorbance is measured at _____nm.
Note: This method measure _______carbohydrates

A

Furan components react with Anthrone reagent to yield a blue- green color solution.
- Absorbance is measured at 620nm.
Note: This method measure reducing and non reducing carbohydrates

62
Q

fehling’s test is commonly used for _____ sugars.

A

reducing

63
Q

in fehling’s test, what is detected?

A

the presence of aldehyde

64
Q

how can aldehyde detected in fehling’s test

A

by reduce deep blue solution of copper(II) to a red precipitate of insoluble copper oxide.

65
Q

to prepare fehling’s solution, 2 solution are required.
Fehling’s “A” uses __ g ________ dissolved in _______containing 2 drops of ______
Fehling’s “B” uses ___g of ______ and ___g of _____in 100 ml of distilled water.

A

Fehling’s “A” uses 7 g CuSO4.5H2O dissolved in distilled water containing 2 drops of dilute sulfuric acid.
Fehling’s “B” uses 35g of potassium tartrate and 12g of NaOH in 100 ml of distilled water.
A: CuSO4.5H20+water+dilute sulfuric acid
B: potassium tartrate+NaOH+water

66
Q

which method quantification of total cho?

A

anthrone, colorimetric, chemical

67
Q

which method quantification of reducing sugar?

A

somogyi-nelson, colorimetric, chemical

68
Q

somogyi-nelson method is the improvement on ___ method. For determination of oligo- and polysaccharides, ______are used before the addition of reagent

A

fehling’s

enzymes

69
Q

what is the priciple of somogyi-nelson methods?

A

aldehyde group of reducing sugar reduces Cu2+–>Cu+ in basic solution.

70
Q

_____ (e.g. fructose) enolize to ____ in basic solution so they are also _____ sugars.

A

Ketoses
aldoses
reducing sugars.

71
Q

how is arsenomolydate produced?

A

ammonium molybdate [(NH4)6Mo7O24] with sodium arsenate (Na2HAsO7)

72
Q

Cu+ reduces the arsenomolybdate to a _____ product

A

stable blue product

73
Q

Absorbance at ____ nm is read and samples are quantified against a standard curve of _____

A

Absorbance at 520 nm glucose

74
Q

Somogyi-Nelson Method Steps

A

1- A solution of Cu2SO4 and NaOH is added to a solution of reducing sugars.
2- The mixture is heated in a boiling water bath.
* Reducing sugars reduce Cu (II) to Cu (I).
3- Add an arsenomolybdate complex reagent (arsenomolybdate complex produced from ammonium molybdate [(NH4)6Mo7O24] with sodium arsenate (Na2HAsO7).
4- Cu (I) reduces arsenomolybdate complex; reduction of the arsenomolybdate complex produces a stable blue color solution that is measured spectrophotometrically.

75
Q

lane&eynon are ___ methods?

A

titration, chemical

76
Q

what is titration methods based on?

A

-is based on reducing action of carbohydrates toward certain metallic salts.

77
Q

what does reducing sugar in sample do for titration method?

A

reduce copper sulfate (CuSO4) from Cu(II) to Cu (I) in alkaline tartrate system (Potassium sodium tartrate, KNaC4H4O6) with NaOH.

78
Q

titration method: titrate cho against?

A

known concentration of CuSO4 in alkaline condition

79
Q

titration method: what is use as indicator?

A

Methylene blue

80
Q

titration method: what happen when all cuso4 is used up

A

reducing sugar will reduce MB to form colorless solution

81
Q

what are disadvs of titration method?

A
  • -the results depend on the precise reaction times, temperatures and reagent concentrations used and so these parameters must be carefully controlled.
  • -it cannot distinguish between different types of reducing sugar.
  • -it is susceptible to interference from other types of molecules that act as reducing agents..
82
Q

titration method: what determine the precise?

A

reaction time, temp, reagent concentration

83
Q

what belong to gravimetric method?

A

Munson & Walker Method

84
Q

describe Munson & Walker Method

A

Carbohydrates are oxidized in the presence of heat and an excess of copper sulfate in alkaline tartrate under carefully controlled conditions
Leads to the formation of a copper oxide precipitate
Reducing sugar + Cu2+ + base—> oxidized sugar + CuO2 (precipitate)

85
Q

Munson & Walker Method is what method?

A

gravimetric method, chemical

86
Q

Munson & Walker Method: what is the amount of precipitate formed directly related to?

A

the concentration of reducing sugars in the sample

87
Q

Munson & Walker Method: how is the amount of precipitate present determined?

A

gravimetrically

88
Q

Munson & Walker Method: suffers from the same disadvantages as the _____ method, nevertheless, it is more _____ and ______.

A

Lane-Eynon method, reproducible and accurate.

89
Q

how to do gravimetrically

A

by filtration
drying
weighing

90
Q

what is oxidation?

A

loss e-

91
Q

what is reduction?

A

gain e-

92
Q

reducing sugar can____ e-? act as ____agent

A

give up

reducing agent

93
Q

oxidizing agent will reduced by_____ e-

A

receive

94
Q

receive e- is ____?____ agent?

A

reduction, oxidizing

95
Q

loss e- is____?____agent?

A

oxidation, reducing

96
Q

when the analyte is total cho for nutrition label, what is the method?

A

Grams of carbohydrate per serving is calculated as total grams of serving minus (g of moisture + g of protein + g of lipid + g of ash)

97
Q

when the analyte is total cho for nutrition label, what is the principle?

A

Total carbohydrate by difference

98
Q

when the analyte is total cho for nutrition label, what is the ad/disad?

A

Indirect and less accurate method
Method is required by US regulations. Should not be used to calculate caloric content because carbohydrate components of dietary fiber,
such as cellulose, provide essentially nocalories

99
Q

when the analyte is total cho, what is the method?

A

Spectrophotometric,

phenolsulfuric acid

100
Q

when the analyte is total cho, what is the principle?

A

Measures all Carbohydrates except sugar alcohols

101
Q

when the analyte is total cho, what is the ad/disad?

A

Solution must be clear,

Requires a standard curve made with the same exact mixture of carbohydrates in the same ratio that occurs in the sample

102
Q

when the analyte is total reducing sugar, what is the method?

A

Spectrophotometric.
Somogyi-
Nelson and related methods

103
Q

when the analyte is total reducing sugar, what is the principle?

A

Primarily used to measure glucose/dextrose, maltose, and other low-molecular-weight oligosaccharides in glucose syrups

104
Q

when the analyte is total reducing suagr, what is the ad/disad?

A

May require extraction Solution must be clear

105
Q

when the analyte is Glucose/dextrose Sucrose, Lactose, what is the method?

A

1) Enzymic assay using GOPOD reagent (spectrophotometric) (2) HPLC

106
Q

when the analyte is Glucose/dextrose Sucrose, Lactose, what is the principle?

A

Both methods specifically determine the amount of glucose in a mixture of sugar

107
Q

when the analyte is Glucose/dextrose Sucrose, Lactose, what is the ad/disad?

A

Higher Specificity Extraction required.

108
Q

when the analyte is fructose, what is the method?

A

高效液相色谱法（英语：high performance liquid chromatography，縮寫HPLC

109
Q

when the analyte is fructose, what is the principle?

A

Specific determination of fructose in a mixture of sugars

110
Q

when the analyte is fructose, what is the ad/disad?

A

N/A

111
Q

when the analyte is starch, what is the method?

A

(1) Hydrolysis of starch to glucose using a mixture of amylases and determination
of glucose using the (GOPOD) reagent (2) Hydrolysis of starch with glucoamylase and determination of glucose with glucose oxidase

112
Q

when the analyte is starch, what is the principle?

A

Specific for starch, including modified starches

113
Q

when the analyte is starch, what is the ad/disad?

A

Does not measure resistant starch. Sample

must be free of glucose or a correction made for it. Amylases must be purified to remove any interfering activities

114
Q

when the analyte is pectin, what is the method?

A

Spectrophotometric. m-Hydroxydiphenyl-sulfuric acid method

115
Q

when the analyte is pectin, what is the principle?

A

Uronic acid

116
Q

when the analyte is pectin, what is the ad/disad?

A

Extraction may be required. Standard curve
is required. Other hydrocolloids containing
uronic acids will interfere

117
Q

when the analyte is dietary fiber, what is the method?

A

Gravimetric (residue after removal of lipids, digestible starch, and protein and subtraction of ash content)

118
Q

when the analyte is dietary fiber, what is the principle?

A

“Total dietary fiber

119
Q

when the analyte is dietary fiber, what is the ad/disad?

A

Does not include low-molecular- weight soluble dietary fiber. Is not a measure of the physiological efficacy of the particular
dietary fiber. Soluble and insoluble dietary fiber can be determined by specific methods for them

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