Step0: Make yourself familiar with the instruments & glassware
juicer
CentrifugeSpectrometer
Cuvettes
Centrifuge
tube
Strainer
Step1: Extract juice from selected fruit/vegetable
click to put
into juicer
Click to turn on
juicer
Step2: Filtration of juice sample
click to
put strainer
click to
filter juice
Step3: Pipette out 5ml strained juice and add into the centrifuge tube A
click
to
pipette out
juice
0000uL
A
Step4: Heat strained juice & take 5ml of it in a centrifuge tube B
click
to
pipette out
juice
0000uL
Heat Juice
Turn on
PT 00℃
ST 00℃
B
step5: Add 5ml of 95% ethyl alcohol in both centrifuge tubes
A
B
click
to
pipette out
alcohol
0000uL
Step6: Put both A and B tubes in the centrifuge machine and centrifuge it for 10 min at 5000rpm
Open
Centrifuge
Place Sample A
Place Sample B
Close Lid
RPM 100
TIM 1
Step7: Pipette out 1ml of supernatant from the centrifuge tubes and add to the seperate cuvettes
B
A
A
B
click
to
pipette out
0000uL
Step8: Add 1 ml of 95% ethyl alcohol to 2 other cubettes
click
to
pipette out
0000uL
Step9: Switch on the UV-vis spectrophotometer and set the wavelength at 420 nm & calibrate it using ethyl alcohol cuvettes
λ=280
Abs=0
place
cuvettes
Close Lid
Press
read
Step10: Replace one ethyl alcohol cuvette (A&B) with supernatant cuvette and measure the absorbance
λ=420
Abs=0.1275
Open Lid
Replace
cuvettes
Press
read
Step11: Observation & Result
Observation
| Sample | Absorbance |
|---|---|
| Fresh Apple Juice (A) | 0.7312 |
| Heated Apple Juice (B) | 0.9147 |
Result
NEB index of fresh apple juice is = 0.7312
NEB index of heated apple juice is = 0.9147
Conclusion
Results indicated that thermal treatment of juices increase the NEB index of the sample