Analysis at Ain Shams University | Flashcards & Summaries

Lernmaterialien für Analysis an der Ain Shams University

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TESTE DEIN WISSEN
How’s the BV determined? 
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It’s calculated gravimetrically through the increase in the oil’s weight by the addition of bromine. 
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TESTE DEIN WISSEN
What are the chemical examinations done using reactions with dbs in FAs ? 
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TESTE DEIN WISSEN
Iodine value
Br value
(SCN)2 value
DV
No. Of parts of I2 absorbed by 100 parts of lipid.
~~~ Br ~~~~. Calculated as IV
~ thiocyanogen ~ calculated as IV
~ maleic anhydride ~~ 
Determines the naturally-occurring non-conjugated unsaturation only.
Determines both the conjugated and the non-conjugated FAs.

For unnatural conjugated FAs determination. 
Used for the detection of adulteration of one oil with another one from a different group. 
~~~
To determine the proportions of unsaturated FAs with IV. 
Detection of hydrogenation 
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TESTE DEIN WISSEN
IV calculation 
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TESTE DEIN WISSEN
IV= (B-E.P) X F of I2 / sample weigh 
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TESTE DEIN WISSEN
Why does thiocyanogen give the same result with both oleic and lanoleic acids ? 
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TESTE DEIN WISSEN
Because it only reacts with 1 db due to steric hinderance caused by its bulky structure. 
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TESTE DEIN WISSEN
What’s meant by inner iodine value ?
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TESTE DEIN WISSEN
the iodine value is determined using the free fatty acids only rather than using the whole lipid. The free FA/s are first separated by saponification then they're extracted by a acidification.
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TESTE DEIN WISSEN
What are drying oils (linseed oil) used for ? 
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TESTE DEIN WISSEN
They’re used in paints, as they form a film upon exposure to air (due to the presence of 3 dbs). 
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TESTE DEIN WISSEN
Detection of adulteration of butter fat. 
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TESTE DEIN WISSEN
  • 1️⃣ Sterol acetate test ↪️ Detects adulteration with vegetable oil.
  • 2️⃣ Butyric acid (C4 FA) percentage↪️ Any decrease in C4 FA %  indicates adulteration of the butter fat.
  • 3️⃣Caproic, caprylic & capric acids (C6, 8 & 10 FAs) percentage
  • ↪️ ⬆️ C6 FA % ➡️ ⬆️ adulteration with palm kernel oil. ⬆️ C6,8,10 FA % ➡️ ⬆️ adulteration with palm kernel oil. ⬇️➡️ adulteration with a hydrogenated oil.
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TESTE DEIN WISSEN
What’s the difference between the enzymatic and alkaline hydrolysis of lipids ? 
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TESTE DEIN WISSEN
Enzymatic hydrolysis (rancidity) ➡️ Happens slowly under bad storage conditions, giving:  MGs & DGs (can give the free FAs if left for a long time).

Alkaline hydrolysis (saponification) ➡️ fast reaction, gives  free FAs directly 
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TESTE DEIN WISSEN
Sterol acetate test. 
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TESTE DEIN WISSEN
Can be used in the detection of adulteration of butter fat (should contain only animal sterol): 
sterol acetate test: 
1. Saponification: isolation of the nonsaponifiable part.
2.  Separation of sterol using digitonin 
3. Reflux with acetic anhydride 
4. Determination of the M.P. of the obtained sterol acetate
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TESTE DEIN WISSEN
Factors affecting the melting point of fats.
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TESTE DEIN WISSEN
Directly proportional relation: 
Chain length, saturation, trans configuration & hydrogenation.

inversely: 
No. of double bonds (unsaturation), the distance between the db & COOH group.
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TESTE DEIN WISSEN
Factors affecting the refractive index of oils.
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TESTE DEIN WISSEN
Directly proportional to:  MWT (chain length) 
Degree of unsaturation (dbs). 

(A highly saturated oil has a high M.P. and a low refractive index).
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TESTE DEIN WISSEN
Why isn’t the melting point of fats a decisive parameter in the analysis of fats ? 
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TESTE DEIN WISSEN
Since it could change according to the geographical source of the fat.
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Q:
How’s the BV determined? 
A:
It’s calculated gravimetrically through the increase in the oil’s weight by the addition of bromine. 
Q:
What are the chemical examinations done using reactions with dbs in FAs ? 
A:
Iodine value
Br value
(SCN)2 value
DV
No. Of parts of I2 absorbed by 100 parts of lipid.
~~~ Br ~~~~. Calculated as IV
~ thiocyanogen ~ calculated as IV
~ maleic anhydride ~~ 
Determines the naturally-occurring non-conjugated unsaturation only.
Determines both the conjugated and the non-conjugated FAs.

For unnatural conjugated FAs determination. 
Used for the detection of adulteration of one oil with another one from a different group. 
~~~
To determine the proportions of unsaturated FAs with IV. 
Detection of hydrogenation 
Q:
IV calculation 
A:
IV= (B-E.P) X F of I2 / sample weigh 
Q:
Why does thiocyanogen give the same result with both oleic and lanoleic acids ? 
A:
Because it only reacts with 1 db due to steric hinderance caused by its bulky structure. 
Q:
What’s meant by inner iodine value ?
A:
the iodine value is determined using the free fatty acids only rather than using the whole lipid. The free FA/s are first separated by saponification then they're extracted by a acidification.
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Q:
What are drying oils (linseed oil) used for ? 
A:
They’re used in paints, as they form a film upon exposure to air (due to the presence of 3 dbs). 
Q:
Detection of adulteration of butter fat. 
A:
  • 1️⃣ Sterol acetate test ↪️ Detects adulteration with vegetable oil.
  • 2️⃣ Butyric acid (C4 FA) percentage↪️ Any decrease in C4 FA %  indicates adulteration of the butter fat.
  • 3️⃣Caproic, caprylic & capric acids (C6, 8 & 10 FAs) percentage
  • ↪️ ⬆️ C6 FA % ➡️ ⬆️ adulteration with palm kernel oil. ⬆️ C6,8,10 FA % ➡️ ⬆️ adulteration with palm kernel oil. ⬇️➡️ adulteration with a hydrogenated oil.
Q:
What’s the difference between the enzymatic and alkaline hydrolysis of lipids ? 
A:
Enzymatic hydrolysis (rancidity) ➡️ Happens slowly under bad storage conditions, giving:  MGs & DGs (can give the free FAs if left for a long time).

Alkaline hydrolysis (saponification) ➡️ fast reaction, gives  free FAs directly 
Q:
Sterol acetate test. 
A:
Can be used in the detection of adulteration of butter fat (should contain only animal sterol): 
sterol acetate test: 
1. Saponification: isolation of the nonsaponifiable part.
2.  Separation of sterol using digitonin 
3. Reflux with acetic anhydride 
4. Determination of the M.P. of the obtained sterol acetate
Q:
Factors affecting the melting point of fats.
A:
Directly proportional relation: 
Chain length, saturation, trans configuration & hydrogenation.

inversely: 
No. of double bonds (unsaturation), the distance between the db & COOH group.
Q:
Factors affecting the refractive index of oils.
A:
Directly proportional to:  MWT (chain length) 
Degree of unsaturation (dbs). 

(A highly saturated oil has a high M.P. and a low refractive index).
Q:
Why isn’t the melting point of fats a decisive parameter in the analysis of fats ? 
A:
Since it could change according to the geographical source of the fat.
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