Food Science


Inverted Sugars

-Inverted sugars are equal amounts of frutose and glucose

-It is obtained by splitting sucrose into two components

- The high sweetness that is sourced from frutose , invert sugars is sweeter that sucrose .

- Found naturally in fruit jucies,jam  and honey

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Intrinsic Vs Extrinsic sugars

Intrinsic Sugar

Found naturally present and built into cellular sturcture of foods. these foods are normally found in fruits and vegtables like apples and carrots

Extrinsic Sugars

These are not incorperated in cells.  These will be free in food or added to the food. They may be present in natural unprocessed foods such as the lactose in milk or frutose in honey

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Name all Sugars - MONO and DISA


glucose and frutose


maltose , sucrose , lactose

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Monosaccharides Vs Disaccharides

  • Monosaccharides - Sugars that cannot be broken down into simpler sugars. These are the simplies sugars
  • They range from 3 to seven carbon atoms . Most common have six (frutose , glucose and galactose) therefore their formula is C6 H12 O6
  • They have the same chemical componsistion howevere their atoms are arranged differently 
  • They are quickly absorbed by the body to provide energy


  • Formed by the combination of two monosaccharides with the elimination of a water molecule.
  • They are all white crystialline solids which are dissolved in water 
  • Examples of these are 
  • Sucrose = fructose + glucose
  • Lactose = galactose + glucose
  • Maltose = glucose + glucose
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Glucose (dextrose)

  • It is the breakdown product of starch digestion, and the main form in which all carbohydrates are used by the body.
  • fruits, honey onions and sweetcorn , potatoes also made used in confectionary
  • Glucose is a reducing sugar which assists in the browning (Maillard Reaction) of baked goods. 
  • It is a white solid and has a melting point of 146C. Glucose is found in fruits, honey, onions and sweetcorn. It is also available as a powder, tablets or a colourless liquid
  • When food is broken down by the body, glucose is formed. It occurs in the blood of all animals because blood carries glucose around the body to cells where it is needed. The level of glucose in the blood is regulated by the hormone insulin which is secreted by the pancreas
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  • It is about one and a half times sweeter than glucose
  • It is reducing sugar and is found in the confectionary industry
  • Fructose is absorbed very rapidly into the body and is used more quickly than ,glucose.
  • It s found in invert sugars
  • It is harmless to people with diabetes
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A dissaccharide and reducing sugar

It is produced during digestion when starch is broken down by enzymes .. amylase  this enzyme is present in our sugar

Produced by the malting process from stach in barley

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Firstly it is NOT a reducing sugar

Produced from sugar beet and

It is very expensive in  the food industry especially in confectionary

It is made from the condensation of glucose and fructose

When sucrose is digested the enzymes split the link between glucose and fructose

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  • This sugar is found only in milk
  • It is a reducing sugar
  • There is more lactose in human milk than cows milk.
  • cows 4-5%
  • humans 6-8%
  • Formed by the condensation of glucose and galactose
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Reducing Sugars

Capable of breaking down fehling's solutions

some examples are glucose , maltose and lactose

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Physical forms of Starch 

- Amylose 

Straight chain form of starch made of a-glucose 

Straight chain - form of a spiral or helix with six glucose units per turn

- it undergoes gelatinisation but after time retorgration occurs with the gel contracting and relasing water (syneresis) 


It has poor gelling qualities 

1 Structal form of starch the other being amylose , made of interconnected short chains of a-glucose 

it has sevral thousand glucose units stored 

It is more difficult to gelatinise than amylose but forms stable gels resistant to retogradation 

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Relative Sweetness

Fructose - 170

Inverted Sugars - 130

Sucrose 100

Glucose - 75

Lactose 15 

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Non Sugars - Simple vs Complex Polysaccharides

Simple Polysaccharides 

Polysaccharides consists of long chains of ONE type of monosaccharide - in this case the monosaccharide is always glucose 

Examples - Starch, Cellulose , glycogen , amylose , amylopectin

Complex Polysaccharides

Polysaccharides are long chains which contain a combination of different monosaccarides  

Examples - Pectins , Gums , xanthan , guar 

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It is a complex polysaccharide 

Sourced from plants and seaweed 

used in the food industry - Their main function in food production are stabilisers , thickeners and emulsifier(maiking oil and water come together) it is used in many food applications to prevent seperation and to thicken. 

Has the ability to absorb large quanities of water. 

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Gelatinisation Of Starch

Ability to form a gel ( thickness) 

Does not dissolve in cold water , it just forms a dispersion  (The breaking up of something 

Thickens at a range of temperature at 85°C


Hydrogen bonding allows a gel network to form, trapping the water and forming a gel on cooling.

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Pectin occurs naturally between plant cellls and cell walls

Pectin Has the ability to form a gel only under the correction conditions an example JAM ( its is a gelling agent)

It has to be 66% sugar

PH level has to be 3.5

A sufficient amount of pectin

Pectin is the most common group of complex polysaccharides.

it is found in fruits and some root vegatables

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are our main source of energy - supply energy for activity

Two types - simple carbohydrates (sugars , short spans of energy)

and complex carbohydrates (starch , giving us long releases of energy)

wheat , cornflour and arrowroot has starch

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Thickening/ Gelatanisation OF starch

When water is cold starch granules do not dissolve but just form a suspension However when the water is heated the viscosity of the mixture increases and provided there is enough starch present a gel is formed 

 1 - in cold water the starch takes up about 25% of its own weight of water Stage

2 - Occurs about 60 Degrees C depending on starch variety The granuels swelling rapidly - taking up between 3 and 10 times their weight in water Stage

3 - So much water has been absorbed up to 20times (Swell) the weight of the granuels ,

 4 -The granuels start to split 

5 - The granuels burst open or split. Strach molecules spill out into the surrounding water and its viscosity (thickness ) increases rapidly

6- The remaing starch granules stick together to form a three dimensional network which cooling forms a gel

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Thicking / Gelatinisation of starch 2

Starches gels at a certain temperature

Large starch granuels eg potato , gel more easily and at a lower temperature than small densly packed granuels such as those of rice

amylose gels more easily than amylopectin

starches richer in amylose gel more easily

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Retrogradtion is a process that takes place in gelatanised starch when the amylose and amylopectin chains realign themselves, causing the liquid to gel.

}The breakdown of the network structure is known as retrogradation.

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Stabilising Food Products

Cellulose and Gum is Used to stablise food products CELLULOSE

Supplies roughage in the diet. Has the ability to hold large amounts of water. } }Forms structural part of plants eg. Stems. } }Amorphous cellulose can absorb large amounts of water, used in slimming foods, as the cellulose swells in the stomach however it is in digestable


They have the ability to absorb large amounts of water , form firm gels under the right conditions ,acts as a thickener , stablisers and an emulsifier , source from plants because some plants produce gum on their stem or fruit  and seaweed , used in the food industry  

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Browning reactions

Caramelisation - when sucrose sugar is heated above its melting point , it has a physical change nd produces caramel , happen more readily without water , however syrups can carmalmise with rapid heating

Maillard Reaction

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