Determine the refractive index of the sample at a constant temperature near 20ºC and obtain corresponding moisture % from the table. If the determination is made at a temperature other than 20⁰ C convert the reading to standard temperature of 20 ⁰C according to the following temperature corrections. For the temperature above 20 ⁰ C - add 0. 00023 per ⁰ C and if the temperature is below 20 ⁰ C - subtract 0. 00023 per ⁰ C

Materials and Reagents

·         Abbe’s refractometer

·         Beakers

·         Pipette

·         Distilled water

·         Tissue paper

·         Acetone

Procedures

1.       Open the prism and thoroughly clean its surface.

2.      With a pipette, drop 4 drops of honey sample on the prism, and close the prisms together.

3.       Rotate the eyepiece in order to obtain a good visibility of the filament intersection and scale in the eyepiece field of view. If the boundary between the dark and bright fields is unclear or colorful, rotate the compensator knob and obtain a sharp boundary line. Then bring the intersection of the eyepiece threads onto the boundary line between the dark and light fields by rotating the knob then read the refractive index on screen of refractometer

4.      After getting the refractive index, look the corresponding moisture content from the table below

Table: Relationship between refractive index and moisture content of honey

References

1.      F.A.O Manuals of Food Quality Control 14 / 8 page 119

2.      I.S.I Hand book of Food Analysis (Part II) – 1984 page 36

3.      A.O.A.C 17^th edition, 2000 Official method 969.38 Moisture in Honey