2.9 Constituent Parts of Honey Flashcards
HONEY - General composition criteria
Honey consists essentially of different sugars, predominantly fructose and glucose, as well as other substances such as enzymes, organic acids and other particles derived from honey collection.
1. Colour. Nearly colourless to dark brown.
2. Consistency. Fluid, viscous or partly or entirely crystallised.
3. Flavour and aroma. Vary but derived from plant origin.
4. Food ingredients. None added
5. Other additions. None except for other honey.
6. Free from organic or inorganic matters foreign to its composition
7. No/not: (except for baker’s honey) Foreign taste or odours, Begun to ferment, Been artificially changed, Been heated in such a way that the natural enzymes have been either destroyed or significantly activated.
No pollen or constituent particular to honey may be removed except where this is unavoidable in the removal of foreign inorganic or organic matter. Not applicable to filtered honey.
HONEY - Detailed composition criteria
- Fructose and glucose content. Blossom honey not less than 60g/100g
- Sucrose content. Most honeys not more than 5g/100g
- Moisture content: All honey less heather not more than 20%, Heather not more than 23%
- Water-insoluble content: All honey less pressed honey not more than 0.1g/100g
Electrical conductivity: not more than 0.8mS/cm
Free acid: All honey except baker’s not more than 50 milli-equivalents acid/kg. Baker’s not more than 80 milli-equivalents acid/kg
Diastase and hydroxymethylfurfural content after processing and blending: Diastase activity (Schade scale) All honey less baker’s and citrus not less than 8
HMF. All honey except baker’s not more than 40mg/kg
Melissopalynology
Analysis of pollen in honey to detect origin of a nectar from which bees procured the honey
Used to combat honey fraud E.G Absence of calluna vulgaris pollen in ‘Heather” honey implies misrepresentation
Has also been used to iidentify sources of poisoning
Method:
Constituents of blossom honey as %
C W A N And EFB
* Carbohydrates
Fructose & glucose 68-72%
Sucrose and maltose 8-10%
Other sugars (eg maltose) 1-5%
* Water 17.5%
* Acids 0.5%
* Nitrogen 0.04%
* Ash 0.2%
* Enzymes Trace
* Flavour and aroma constituents Trace
* Breakdown products TraceWhat does the enzyme invertase in honey do?
It is required to breakdown sucrose into glucose and fructose.
What does the enzyme glucose oxidase do?
It breaks down glucose into gluconic acid and hydrogen peroxide
Carbohydrates (sugars)
Mono = Fun & Games 68-72% Di = Sadism & Masochism 8-10% Tri = Melitoze 1-5%
Taken together, sugars make up between 95 and 99% of the solids in honey.
They can be classified by their chemical complexity into four classes:
Monosaccharides: Fructose and Glucose, in ratio 6:5 except in Rape honey (68 - 72%)
Disaccharides: Sucrose 1-3% and Maltose ~7% (8 – 10%)
Trisaccharides: 15 identified most important Melizitose
(1 – 5%)
Higher Sugars: At least 2 identified; contain 4 and 5 sugar molecules (< 1%)
Acids
Although acids comprise only about 0.5% of honey they have important effects:
1 Reduce pH to 3.9
2 Contribute to the stability of honey against micro organisms
3 Contribute to the flavour of the honey
The main acid is gluconic acid, which is formed by the action of the enzyme glucose oxidase on glucose. The reaction also produces hydrogen peroxide which is not sufficiently stable to remain for any length of time.
19 other acids have been identified, among which are formic acid, acetic acid, citric acid, lactic acid and oxalic acid.
Nitrogen
40 – 65% of nitrogen is in the form of proteins but there are some free amino acids.
Free amino acids react slowly at room temp, faster at higher temps.
The proteins originate from pollen and from enzymes and other proteins introduced by the bees.
The presence of proteins lowers the surface tension of honey and causes it to foam and produce scum.
The higher concentrations found in ling heather and manuka honeys produce thixotropic effects.
Free amino acids react slowly with sugars at room temperature, more quickly at higher temperatures. This is thought to cause honey to darken on storage or when heated.
Ash
Ash is material left over when honey is heated to a high temperature and is caused by the presence of minerals. Potassium is usually the largest component but there are very many more.
Invertase (sucrose)
Used by the bees to break sucrose down into glucose and fructose. Some enzyme activity remains in the honey. The reaction is reversible, i.e. invertase can cause glucose and fructose to recombine into sucrose. This may be the reason why all honeys contain a small amount of sucrose.
Glucose oxidase
Breaks glucose down into gluconic acid and hydrogen peroxide and is one of the major factors responsible for the antibacterial properties of honey.
Diastase (amylase)
Breaks starch down to simpler compounds. Its exact function in honey is unknown but bees use the enzyme to break pollen down.
Measured with the Schade scale
All honey = not less than 8 schade
At what temperature do enzymes in honey start to break down?
Enzymes start to break down at temperatures above 45°C
Flavour and aroma constituents
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Many chemical compounds have been identified which are present in very small quantities but are responsible for giving honey its individual character. They mainly fall into 4 classes of chemical:
1 Alcohols
2 Aldehydes and ketones
3 Acids
4 Esters
The more volatile chemicals are lost quite quickly once the honey is removed from the hive and this is the main reason why the flavour of honey tends to decline as it ages.
