Materials required

Juice sample
Beaker
Conical flasks
Measuring cylinder
Pipette
Strainer
Hot plate
Mechanical centrifuge
UV-VIS spectrophotometer
95% ethyl alcohol

Methods

1. Extract juice from selected fruit/vegetable using electronic juicer.
2. Filter the juice sample using strainer.
3. Pipette out 5 ml strained juice and add into the centrifuge tube A.
4. Heat 10 ml of strained juice and take 5 ml of it in a centrifuge tube B.
5. Add 5 ml of 95% ethyl alcohol in the both centrifuge tubes.
6. Put both A & B tubes in the centrifuge machine
7. Centrifuge the mixture for 10 min at 5000 rpm.
8. Pipette out the supernatant from the centrifuge tubes and add to the separate cuvettes.
9. Add 1 ml of 95% ethyl alcohol to two other cuvettes.
10. Switch on the UV-vis spectrophotometer and set the wavelength at 420 nm.
11. Calibrate the UV-vis spectrophotometer by placing the ethyl alcohol cuvettes.
12. Replace one ethyl alcohol cuvette with supernatant cuvette and measure the absorbance.
13. This absorbance value is used to determine NEB index of the selected sample.