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Food Analysis > Carbohydrate Analysis Slides > Flashcards

Carbohydrate Analysis Slides Flashcards

1
Q

What are carbohydrates
Empirical Formula:

A

Compounds of Carbon, Hydrogen and Oxygen

CnH2nOn

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2
Q

Carbohydrates functional role in food

A

Bulk
Viscosity
Water Holding Capacity

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3
Q

Classification of CHOs

A

1) Monosaccharide
2) Disaccharides
3) Oligosacharides
4) Polysaccharides

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4
Q

Examples of monosaccharides

A

Glucose and Fructose
(easily absorbed)

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5
Q

Examples of Disaccharides

A

Lactose, Sucrose, and Maltose

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6
Q

Only polysaccharides digested by humans

A

Starch

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7
Q

Sugars =

A

sum of all free mono- and disaccharides

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8
Q

Sugar Alcohols =

A

alditols, polyhydroxyalcohols, polyols, sorbitol, and xylitol

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9
Q

Other carbohydrate =

A

total carbohydrate - (dietary fiber + sugar)

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10
Q

Total carbohydrate =

A

100% - (% Moisture + %Ash + %Lipid + %Protein)

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11
Q

Test for Hexose or Pentose

A

Bial Test

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12
Q

Test for aldose or ketose

A

Seliwanoff test

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13
Q

Reducing sugars test

A

+ Benedict’s test

+ Barfoed’s Test

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14
Q

Test for starch or glycogen

A

Iodine test

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15
Q

Quantitative chemical methods

A

Phenol-sulphuric
Somoygi-Nelson
Dinitrosalicyclic method

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16
Q

Quantitative chromatography method

A

HPLC
Gas chromatography
Thin-Layer
Paper

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17
Q

Preparation of sample

A

1) Drying
2) Grinding
3) Extract lipids

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18
Q

Bial’s Test Reagents

A

FeCl3 or HCl

to give blue color: positive of pentoses

19
Q

Dehydrated ketose reacts with resorcinol to produce

A

cherry red color (Seliwanoff’s Test)

20
Q

Principle of Phenol-Sulfuric Acid Method

A

Carbohydrate treated with strong acid/heat form furan derivatives

21
Q

Benedict’s Test (reducing sugars)

A

Alkaline solutions of copper are reduced by sugars having free aldehyde or ketone group

22
Q

Seliwanoff’s Test distinguishes between

A

Aldose and ketose sugars

23
Q

When heated ketoses dehydrate

A

more rapidly than aldoses

24
Q

Examples of ketose monosaccharides

A

Dihydroxyacetone
Erythrulose
Ribulose
Fructose

25
Q

Examples of aldose monosaccharides

A

Glyceraldehyde
Erythrose
Ribose
Xylose
Glucose
Mannose
Galactose

26
Q

Barfoed’s test is used for

A

detecting the presence of reducing monosaccharides

27
Q

Barfoed’s Test is based on the

A

reduction of copper (II) acetate to copper (I) oxide (Cu2O) (brick red)

28
Q

In got acidic medium starch is _______ and dehydrated to _____

A

hydrolyzed to glucose; hydroxymethyl furfural

29
Q

Methods for total reducing sugar

A

Somogyi-Nelson
Munson-Walker
Lane-Eynon

30
Q

Principle for total reducing sugar

A

Sugars with aldehyde group act as reducing agents - they reduce Cu2+ to Cu+

31
Q

Starch contain what two polysaccharides

A

Amylose (linear) and Amylopectin (branched)

32
Q

Most starches contain

A

15 - 35 % amylose

33
Q

Amylose are linked together by

A

alpha 1,4 linkage

34
Q

Amylopectin are linked together by

A

alpha 1,4 and alpha 1,6 linkage

35
Q

Amylose is _____ in water, while amylopectin is ______

A

soluble; insoluble

36
Q

Amylose gives what reaction in iodine solution vs amylopectin

A

Blue color vs no reaction

37
Q

Give rise to; Amylose vs Amylopectin

A

Gel formation vs Thickened preparation

38
Q

Starch usually contain more

A

amylopectin than amylose

39
Q

Starch Gelatinization: Heat causes

A

1) Water absorption by amyloplasts

2) Rupturing of the amyloplasts

3) Starch network formed

4) Hydrated network with water pockets

5) Gelatinization

40
Q

Factors influencing gelatinization

A

+ Types of starch
+ Water
+ Temperature
+ Stirring
+ Addition of other ingredients

41
Q

Starch Dextrinization

A

Starch and dry heat

42
Q

Starch –> Dextrin; which provides

A

flavor, color, and aroma

43
Q

Gel formation: Upon cooling

A

the realignment of starch molecules with water being squeezed out

Food Analysis (15 decks)

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