Page 107 - Feed Lab

Estimation of peroxide value in animal protein sources Suguna Management System Ver 1.0 / SOP / FQL / P2 - 23 Page 2 of 2

titrate with 0.01N sodium thiosulphate with
REAGENTS
vigorous shaking until yellow is almost gone. Add 1
FAcetic acid: Chloroform (3: 2)
ml starch solution and continue titration, shaking
FPotassium iodide solution saturated, AR grade vigorously to release all iodine from chloroform layer
(stored in amber colour bottle) until blue colour disappears. Conduct a blank
estimation and subtract from sample titration.
FSodium thiosulphate, 0.01N, 0.26g / 100 ml which (Picture - 10)
is standardized by taking 10 ml of 0.01N potassium
dichromate + 5 ml of concentrated hydrochloric
acid + 0.2 ml of saturated potassium iodide and
titrate against sodium thiosulphate using starch as
indictor. The end point is change of disappears of
blue to colour.

FStarch solution, 1% T.S. freshly prepared

FPotassium dichromate, 0.01 N. 0.05g / 100 ml, AR
grade Picture - 6 Picture - 7

FHexane SQ, AR grade.

PROCEDURE
FTake 24cm diameter of Qualigens filter paper
no.615A or whatman filter paper no.1 and fold like
thimble. (Picture - 6)

FWeigh 20gm of MBM or fishmeal sample into this
thimble and close well by stapler pin. Please ensure
Picture - 8 Picture - 9
that sample should not come out from the thimble.
(Picture - 7)

FExtract the oil content using Soxhelt apparatus by
hexane for 4 hours in dry flatted bottom 250ml
boiling flask. (Picture - 8)

FAdd 6ml of acetic acid chloroform mixture to this
flask and mix thoroughly. Then add 0.5 ml of
saturated potassium iodide solution to this flask
and let it is stand for exactly 60 seconds with Picture - 10
occasionally shaking in dark room. (Picture - 9)
Note: If blue or violet colour is not obtained then sample
FAdd 30 ml of distilled water and shake well. Slowly
will be no rancid or peroxide value is nil.

CALCULATION
Where,
(S-B) X 1000 X N
Peroxide value (µ / Kg) = --------------------------- S - Volume of sodium thiosulphate in sample.
B - Volume of sodium thiosulphate in blank.
Sample weight, g
N - Normality of sodium thiosulphate.

REFERENCE
Association of Official Analytical Chemist 2000.

Prepared by : Approved by :
95 Director - Technical