ΦΥΣΙΚΑ ΧΑΡΑΚΤΗΡΙΣΤΙΚΑ ΤΟΥ ΜΕΛΙΟΥ

Physical characteristics of Honey

Colour: As per Pfund Grader:

Water White: Extra White: White: Extra Light Amber: Light Amber: Amber: Dark Amber:

0 - 9mm 9 - 19mm 20 - 34mm 45 - 50mm 51 - 85mm 86 - 114mm > 114mm

Specific Gravity: Dependent on Water content:
15.0% moisture @ 20°C 1.423 approx.
18.0% moisture @ 20°C 1.417 approx.
*** Floral source can also affect Specific Gravity

Viscosity:
Temperature and moisture content are the main determinants of viscosity. Viscosity of Honey decreases rapidly as the temperature rises. A change of 1% moisture is equivalent to about 3.5°C in its effect on viscosity. Nectar source will also have an impact on viscosity. In most cases this is minor but in the case of thixotropic honeys (for example manuka), this may be greater.

Some typical values for clover honey

At 16% moisture 14°C 20°C 30°C 40°C 50°C 70°C

600 poise 190 poise 65 poise 20 poise 10 poise 3 poise

At 25°C 13.7% moisture 14.2% moisture 15.5% moisture 17.1% moisture 18.2% moisture 19.1% moisture 20.2% moisture 21.5% moisture

420 poise 270 poise 138 poise 70 poise 48 poise 35 poise 20 poise 14 poise

Hygroscopicity
Honey will reach an equilibrium of moisture content depending on the relative humidity, and will generally speaking absorb moisture from the air until that equilibrium is reached. This may make the honey more susceptible to fermentation.

Also this characteristic may be of interest in food preparations containing honey, where the tendency to stay moist may be an advantage, or a disadvantage depending on the finished product. The composition of the two main sugars in honey (glucose and fructose) will affect the hygroscopicity (fructose being the main hygroscopic component) and these are in turn a function of honey source.

Crystallisation
The two major sugars in honey (glucose and fructose) are the main factor in determining the tendency for a honey to crystallise. Water content also plays a part. Generally the higher the glucose, the faster honey crystallises and the higher the fructose, the slower it crystallises.

Three formulas have been proposed for prediction of crystallisation tendency.

1. Glucose / Water. 2. Fructose / Glucose 3. (Glucose-Water) / Fructose

<> 1.64 stays liquid <>

> 2.1 will crystallise <> > 0.42 will crystallise

Other factors can also play a part in crystallisation that may affect the above formulas' ability to accurately predict crystallisation tendency. These include higher molecular weight sugars (oligosaccharides), acidity and Available Water.

Specific Heat:
Liquid Honey: 0.54 - 0.60 (higher moisture content = higher SH value) Creamed Honey: up to 0.73

Thermal Conductivity:
from 118 X 10-5 to 143 X 10-5 cal/cm sec°C

Colloidal Properties:
Isoelectric point: 4.30

pH Balance:
3.9

Freezing Point:
15% solution from -1.43 to -1.53° C
68% solution -12.01°C

Water Activity:
0.5 - 0.6 AW