2.25 Composition of Nectar and its variants

Question 1

Composition of Nectar

TPANTS

Answer 1

30-90% water
Sugars 5-70%
Rest 3%:

Traces of nitrogen compounds, minerals, organic acids
Pigments and aromatic substances
Ash - content ranges from 0.023-0.45%
Nectar has a pH of 2.7-6.4
Traces of vitamins; thimne, riboflavin, pyroxide, nicotinic acid, panthothenic acid, folic acid, biotin and ascorbic acid
Sugars varying in concentrations 5-80%

Question 2

Differences in the composition of nectar and honey

Answer 2

Water content Nectar 30%-90% r - Honey <20% water
Honey more viscous
Sugar content Nectar 5-60% - Honey 80%
Nectar = colourless
Bees add enzymes to nectar to convert it to honey

Question 3

Converting nectar to honey

Answer 3

Foragers insert their proboscis into the nectar and suck up trough the food canal
Enzyme invertase is added from the bee’s hypopharangeal gland
This starts process of breaking down the sucrose (a dissacharide) into glucose and fructose (mono-saccharides)
Nectar then stored in honey crop
Back at the hive the nectar is transferred to house bee by process of trophallaxis
House bees evaporate water from the nectar by regurgitating it numerous times by many bees then spreading to dry in a cell. More invertase is added during this process.
The bees fan both within the hive and at the entrance to keep air circulating and maintaining humidity at 40-50%. These air currents are essential part of reducing the water content to below 20%.
The honey is sealed in the cell with a wax capping when the water content is around 18%. The wax capping excludes both air and water.
When capped the honey is said to be ‘ripe’ and will keep for a long time.
In the ripening process the bees break down the sucrose into glucose and fructose which is facilitated by the enzyme invertase (a dilute acid) from the hypopharyngeal gland:

Question 4

Chemical equation of nectar converted into honey

Answer 4

C12H22O11 (sucrose) + H2O (water) with invertase = C6H12O6 (Glucose) + C6H12O6 (fructose)
Another enzyme produced in the hypopharyngeal gland is glucose oxidase.
This acts on glucose to convert it into hydrogen peroxide and gluconic acid. The hydrogen peroxide helps preserve the honey by destroying bacteria.
C6H12O6 (glucose) + O2 (oxygen) with glucose oxidase = C6H12O7 (gluconic acid) + H2O2 (hydrogen peroxide)