Analytical Methods to Measure the Constants of Fats and Oils

(1)

AV =

AV = ml of KOH x N x 56ml of KOH x N x 56 W

Weigheight ot of Saf Sammpleple = mg of KOH= mg of KOH

ANALY

TICAL METHODS

TO MEASURE

THE CON

STA

NTS OF FA

TS

AND OILS

[1] Acid value (Acid Numbe!

+he

+he acid acid ,alue ,alue -- AV) is AV) is the number that epresses in milligrams the uantit& o" potassium the number that epresses in milligrams the uantit& o" potassium h&droide reuired to neutrali1e the "ree acids present in ( g o" the substance.

h&droide reuired to neutrali1e the "ree acids present in ( g o" the substance. +he acid ,alue+he acid ,alue ma& be

ma& be o,ereso,erestimattimated ed i" other acid components are present in the i" other acid components are present in the s&sts&stemem e.g.e.g. amino acids or amino acids or acid phosphates. +he acid ,alue is o"ten a good measure o" the brea% down o" the triac&lgl&crols acid phosphates. +he acid ,alue is o"ten a good measure o" the brea% down o" the triac&lgl&crols into "ree "att& acids which has an ad,erse e""ect on the ualit& o" man& lipids.

into "ree "att& acids which has an ad,erse e""ect on the ualit& o" man& lipids.

Si"#i$ica#ce Si"#i$ica#ce

2cid ,alue is the measure o" h&drol&tic rancidit&. n general it gi,es an indication ab

2cid ,alue is the measure o" h&drol&tic rancidit&. n general it gi,es an indication ab out edibilit&out edibilit& o" the lipid.

o" the lipid.

' dible oil contain  (6 ' dible oil contain  (6 '

' Pharmaceutical oil must Pharmaceutical oil must not ha,e an& acidit&not ha,e an& acidit&..

7

7 = = 7ormalit& 7ormalit& o" o" 99

6

6 Free Free Fatt& Fatt& 2cid 2cid -FF2; -FF2; = = 22< <   0.5030.503

Ma%eial

Ma%eial •

• Fat Fat or or 9il9il

•

• 2bsolute 2bsolute ethanol ethanol alcoholalcohol

• • Phenolphthalein Phenolphthalein • • 0.( 0.( 7 7 99 &'cedue &'cedue (.

(. Place 5.Place 5.0 g o" "a0 g o" "at or oit or oil in a drl in a dried coniied conical "lcal "las%.as%.

).

). 2dd )5 m2dd )5 ml o" absoll o" absolute ethanol alute ethanol alcohol and add cohol and add - )'3; - )'3; drops o" drops o" phenolphthaleinphenolphthalein

3.

3. eaeat t witwith h shasha%in%ing g in water bath -56; "or (0 in water bath -56; "or (0 miminutnutes es ththen cool en cool +i+itratrate the te the solsolutiutionon

against 0.( 7 9 until pin% color appears -end point;.

4.

4. ecord ecord &our &our obserobser,atio,ations.ns.

5.

5. >alculate the acid ,alue -2>alculate the acid ,alue -2<<; and "ree "att& acid -; and "ree "att& acid -6FF26FF2; using abo,e laws.; using abo,e laws.

)@

(2)

9 > = 9 9 > = > = 9 :₎> 9 :> 9 :₎> 9 89: : : : :₎> 9 :> 9 :₎> 9 = > 98 + 3 + 3

+he saponi"ication ,alue is the number o" mg o" potassium h&droide reuired to neutrali1e the "ree acids and to saponi"& the esters in ( g o" the substance. +he saponi"ication number is a measure o" the a,erage molecular weight o" the triac&lgl&cerols in a sample. Aaponi"ication is the process o" brea%ing down a neutral "at into gl&cerol and "att& acids b& treatment with al%ali. +he smaller the saponi"ication number the larger the a,erage molecular weight o" the triac&lgl&cerols present i.e. Aaponi"ication ,alue is in,ersel& proportional to the mean molecular weight o" "att& acids -or chain length;.

Aaponi"ication <alue o" Fats and 9ils

Fat or oil Aaponi"ication <alue

Bil% "at )(0')33

>oconut oil )50')4

>otton seed oil (8!'(!8

Ao&bean oil (8!'(!5

lard (!0')0)

Cutter "at and ,egetable "ats

∼

))0 D )50

Baterial

• Fat or 9il

• 0.5 7 alcoholic potassium h&droide - alcoholic 9; - prepared b& dissol,ing 30 g

potassium h&droide in )0 mL o" water and ma%e the "inal ,olume to ( L using !5 6 ethanol. Lea,e the solution to stand "or )4 h be"ore decanting and "iltering the solution.

• 0.5 7 &drochloric acid • Phenolphthalein.

Procedure

(. Eeigh approimatel& ) g o" the "at or oil into a )50 mL conical "las%. ). 2dd )5 mL o" alcoholic potassium h&droide solution - 0.5 7;.

3. 2ttach a re"lu condenser and heat the "las% contents on a boiling water bath "or ( hour with occasional sha%ing.

(3)

SP# =

56.1! "S x N of H$l

%&am of Sa mple

4. Ehile the solution is still hot  add 3 drops o" phenolphthalein indicator and titrate the ecess potassium h&droide with the 0.5 7 h&drochloric acid - <ml o" h&drochloric acid at end point represents A;.

5. o same abo,e procedure but without sample - <ml o" h&drochloric acid at end point represents C;.

. calculate the saponi"ication number b& using the "ollowing law:

3@ ster <alue

T)e e*%e value is de"ined as the mg o" 9 reuired to react with gl&cerin -gl&cerol / or gl&cerin; a"ter saponi"& one gram o" "at. t is calculated "rom the saponi"ication

<alue (SV) and the acid <alue -2<;:

E*%e +alue (E+! , Sa'#i$ica%i'# +alue (S+! - Acid +alue (A+! . glycerin Ester Value /0/2332

4@ odine <alue -.<;

+he iodine ,alue - IV ; gi,es a measure o" the a,erage degree of unsaturation o" a lipid: the higher the iodine ,alue the greater the number o" >=> double bonds. C& de"inition%)e i'di#e value i* e4e**ed a* %)e "am* '$ i'di#e ab*'bed e 1//" '$ liid0 odine ,alue -.<.; is directl& proportional to the degree o" unsaturation -7o o" double bonds.; and in,ersel& proportional to the melting point -B.P.; o" lipid. 2n increase in .<.indicates high susceptibilit&

o" lipid to oidati,e rancidit& due to high degree o" unsaturation.

9ne o" the most commonl& used methods "or determining the iodine ,alue o" lipids is Ganus methodG. +he lipid to be anal&1ed is weighed and dissol,ed in a suitable organic sol,ent to which a %nown ecess o" iodine chloride is added. Aome o" the Cr reacts with the double bonds in the unsaturated lipids while the rest remains:

'>=>' H Cr ecess → '>'>Cr' H Cr remaining

+he amount o" Cr that has reacted is determined b& measuring the amount o" Cr remaining a"ter the reaction has gone to completion -Cr reacted =Cr ecess ' Cr remaining;. +he amount o" Cr

C: ml o" >l reuired b& Clan%. A: ml o" >l reuired b& Aample.

(4)

remaining is determined b& adding ecess potassium iodide to the solution to liberate iodine and then titrating with a sodium thiosul"ate -7a)A)93; solution in the presence o" starch to determine

the concentration o" iodine released: Cr remaining H )→ Cr H  H )

) H starch H )7a)A)93 -blue; → )7a H starch H 7a)A49 -colorless;

TY&ICAL IODINE NUM5ERS

>oconut oil 8 ' (0 Cutter )5 '40 Cee" tallow 30 ' 45 Palm oil 3# ' 54 Lard 45 '#0 9li,e oil #5 ' !5 Peanut oil 85 ' (00 >ottonseed oil (00 ' ((# >orn oil ((5 ' (30 Fish oils ()0 ' (80 Ao&bean oil ()5 ' (40 Aa""lower oil (30 ' (40 Aun"lower oil (30 ' (45 Linseed oil (#0 ' )05 Baterial • 9il or "at

• anus solution - itIs prepared b& dissol,ing (8.) g o" iodine in (L o" glacial acetic acid

and then add 3 ml o" bromine water "or increasing the halogen content.

• (56 potassium iodide solution • (6 starch solution

• 0.( 7 Aodium thiosul"ate solution.

Procedure

(5)

). 2dd (0 ml o" chloro"orm.

3. 2dd 30 ml o" anus solution and close the "las% completel& b& Para "ilm then lea,e the solution "or 30 minutes with sha%ing continuousl&.

4. 2dd (0 ml o" (56 potassium iodide solution and then sha%e. 5. 2dd (00 ml o" distilled water -E;.

. +itrate the iodine solution against 0.( 7 Aodium thiosul"ate solution till &ellow color "ormed  then add )'3 drops o" starch solution where blue solution "ormed and then continue with titration till the blue color is disappeared -<olume -ml; o" 7a)A)93at end point represents A;

#. o same abo,e procedure but without sample -<olume -ml; o" 7a)A)93 at end

point represents C;.

8. >alculate the iodine number b& using the "ollowing law:

- C ' A ; × 7 o" 7a₎A₎9_{3 ×} 0.()#g/me × (00

odine <alue =

Eeight o" Aample -g;

C: < ml o" 7a)A)93 ,olume "or blan%