viscometry

1. Basic Rheological studies
of some Fruit Juices
BasicRheologicalstudiesof
some FruitJuices

2. TO KNOW SURFACE TENSION OF FRUIT JUICES BY THE
TECHNIQUE OF STALAGMOMETER
 This method use of a device called stalagmometer
(means drop measurer).
 The lower part of stalagmometer consist of a fine
capillary tube through which the liquid can flow.
 The upper and the lower portions are graduated to
measure fractions of a drop.
 The upper portion of the stalagmometer is connected
to a ‘Y’ shaped glass tube by a rubber tubing.
 One arm of Y shaped tube is connected to a pinch
cork and the other to a screw clamp.

3.  Before any liquid is taken in the stalagmometer it
should be cleaned and dried.
 The pinch cork is opened and the given liquid is
sucked up to a level above mark.
 The pinch cork is then closed and the screw clamp
is gradually opened to regulate the number of drops
flowing out.
 The number of drops formed as the liquid flows
from mark is measured.
 Let n1 be the number of drops formed by the given
liquid with density d1 and surface tension γ1 and
n2 be the number of liquid drops , d2 density and
γ2 be the surface tension of the reference liquid.
 Then using equation:
γ1/γ2=n2/n1*d1/d2

4. TO KNOW THE VISCOCITYOF FRUIT JUICE BY THE
TECHNIQUE OF VISCOMETRY
 Clean the viscometer thoroughly with chromic acid and
with distilled water.
 Dry it by passing hot air through it.
 Clamp the viscometer in the vertical position on a retort
stand.
 Pipette out 10cmз of distilled water and transfer it in
the right hand lind i.e.bulb.
 Suck the distilled water so that it reaches above the
mark in the bulb.
 Gradually losen the screw clip and allow the distilled
water to reflow through the capillary tube under its own
weight.

5.  When then distilled water miniscus reaches the
mark start the stopwatch , and when the
distilled water miniscus pases the mark stop the
watch immideately.Note down the time in
seconds as t1.
 Adjust screw clip position in such a manner that
for the distilled water it will give flow time of 100
-120 seconds.
 Find out the mean time of flow of the distilled
water in seconds as mean t1.
 Then using equation:
η1/η2=t1*d1/t2*d2
η2=η1*t2*d2/t1*d1

6. RESULT
LIQUID SURFACE
TENSION (N/m)
VISCOSITY
(Poise)
DENSITY
DISTILLED
WATER
0.0728 0.0085 1.0
NATURAL FRUIT
JUICES
ORANGE 0.09 0.0124 1.02
GUAVA (diluted) 0.0072 0.00094 1.002
SWEET LIME 0.110 0.0124 1.03

7. ARTIFICIAL
FRUIT JUICE
ORANGE
(diluted)
0.025 0.00345 1.02
GUAVA (diluted) 0.0274 0.00142 1.01
SWEET LIME
(diluted)
0.0322 0.01015 1.01

8. CONCLUSION:
•Jam is an effective and tasty way of preserving
fruit. Most tropical fruits can be processed and
preserved in order to reduce post harvest loss in
small scale operations. These fruits are used in
the preparation of jam and jelly having high
viscosity and surface tension than distilled water
which is also used for preparation of jam and
jelly

9. • concentration of sugar, has the property of
forming a viscous semi solid.If this
charactersitc of sugar get mixed with the
high viscosity and surface tension of the
fruits then there will be fast formation of
jam and jelly.This characterstic also
increases the stability of solid in liquid
colloids.

10. THANK
YOU