Food Properties (2024)

Functional Property: Caramelisation
Definition/Explanation of Property: Caramelisationis thechemical reactionin whichmonosaccharides and disaccharides turn brown with the application of heat(i.e. any product containingsugarmay caramelize upon heating.) This occurs when products containing fruits, honey, milk, sugar cane, maple syrup and cereals come in contact with heat. Although not often recognized, Caramelisation is responsible for many browning processes. A good example of this the colour of toffee.

Examples of practical applications:

• Caramelisation occurs in:
  
• Browning of biscuits
  
• Cakes and other baked products
  
• Commercial milks
  
• Ice-creams
  
• Honeycomb (Violet crumbles)
  
• Crème Caramel

The degree of Caramelisation that occurs varies according to:

• the amount of sugar used
  
• the length of heating time
  
• the type of sugar
  
• the addition of other ingredients
  
• the temperature the sugar reaches

Functional Property: Dextrinisation
Definition/Explanation of Property:Dextrinisationis the process involvingthe browning of starch foods when subjected to dry heat.It is defined as the breakdown of starch into dextrin’s (disaccharides.) It is anon-enzymatic browning and chemical changewhich is easily digested as partial breakdown is complete. The characteristics of colour, taste, aroma and flavour may change as a result of this process.

Examples of practical applications
·Toasting bread
·Baked goods
·Brown gravies and sauces
·Toasted breakfast cereals, Formation of baked crusts on vegetablese.g. potatoes, pumpkin and onions

The degree of Dextrinisation is determined by:
·thelength of timethe product isheated;
·thetemperature,
·the type of starchin the product;
·addition of other ingredients;
·the action of certainenzymes,
·the action ofacids; and
·theamount of exposure to dry heatthe product encounters.

Functional Property: Geletinisation

The process wherein starch granules form asuspensionin cold water.When heated in the presence of water, these swell and thickenand a gel results. The cellulose wall of the starch ruptures when swollen granules bump into each other and water is absorbed. This process is known as Gelatinisation.

• Lemon Meringue Pie (filling)
  
• Roux
  
• Cheese Sauce
  
• Custard
  

Factors Affecting Functional Property

• Temperature(control of, to prevent burning whilst ensuring boiling point is reached);
• Ratio of starch to liquid(in accordance with useandtype of starch used.
• Length of time product is heated;
• Degreeof agitation(i.e. constant, steady stirring is required for effective gelatinisation.
• Addition of other ingredientse.g. acids , stabilizing agent, sugar.
  

Functional Property: Crystallisation

Crystallisation is the result of thecooling of a supersaturated solution(very concentrated) where solid crystals form. This occurs after substancesseparate from solutions or where a change from a liquid to a solid causes crystals. The result will occur only at very high concentration levels and is seen in the main in sucrose (and sometimes lactose and maltose. )

Examples of practical applications

• Fudge
  
• Toffee
  
• Caramel
  
• Fondant

The size of crystal formation is dependent on these factors:

• ·therate of the formation of nucleii.e. the bases of crystal growth;therate of growth of the crystals.
• The rate of crystal growth can be affected by:The concentration of sugarin the solution.
• Theconcentrationof sucrose(disaccharide whichincreases rate ofCrystallisation)
• Thetemperatureof the solution;
• Stirringthe solution causes a grainy textured product as Crystallisation occurs too fast;
  
• Addition of additives such as fats, honey, corn syrup or cream of tartaralso change the form of the product.
  

Functional Property: Coagulation, Denaturation and Syneresis

Two important processes are denaturation and coagulation. The denature means to change properties; once a protein has denatured, it cannot return to its original form. An example of this is the application of heat to egg. the second step of denaturation is coagulation, whereby protein thickens and changes into solid mass. The process of denaturation and coagulation is affected by the application of acid, alkalis, sugar and salt.
Syneresis occurs when the coagulation process continues due to heating. This is seen when the protein squeezes out the liquid in the product, for example curdling in custards, the separation of liquid from meat when it is cooked to well done and the weeping of liquid from meringue on top of a lemon meringue pie.

• Raw eggs to cooked (scrambled, boiled)
  
• Production of Cheese
  
• Baked/fried fish
  
• Creme Caramel
  
• Meringue (protein denatured during beating; heat causes coagulation)

• HighTemperature- the higher the temperature, the faster coagulation will occur. Over heating causes a gel to firm.
• Agitation( excessive mechanical action may cause over coagulation);
• Theaction of enzymes e.g. rennin causing milk to coagulate;
• Achange in pH; and
• Theaddition of salt- begins the process of denaturation.
  

Functional Property: Aeration

Foams are the process ofwhipping or beating air into a liquid(generally lipids.) Foams are a type ofaeration. In this process, fat in the product becomes partially solidified and protein partially denatured. They are an extremely efficient way to incorporate air. They rely on themechanicaluse of instruments to create spaces for oxygen to enter although excessive beating can cause a structural breakdown of the product.

Examples of practical applications

• Cream
  
• Pavlovas
  
• Sponges
  
• Meringues
  
• Roulades
  
• Soufflés
  
• Mousses
  
• Omelette

Factors Affecting Functional Property
Factors affecting the rate and effectiveness of foaming include:

• The productbeing beaten;
  
• The length of beating time;
  
• The severity of the beating;
  
• The use ofadditivese.g. gelatine or sugar;
  
• The age of the product(especially in products such as cream);
  
• Thetemperatureof the product.
  

Functional Property: Emulsification
Definition/ Explanationof property: Emulsification is the dispersal of fat or oil throughout a liquid. Oil and water do not mix, so emulsification requires the use of a third ingredient. If oil and water are beaten for a period of time, the oil is reduced to very small droplets that appear to be distributed in the water. However if the mixture is left to stand for a while, it will separate. An example of this is a clear salad dressing, such as french dressing. Egg yolk, salt, paprika, and mustard are emulsifying ingredients that work by wrapping around the small oil droplets, preventing them from joining back together and separating from the water on standing.

Examples of Practical Applications:

• Mayonaise
  
• gravy
  
• cheese

TASK:

Design a series of posters to illustrate the functional properties of Carbohydrates, proteins and lipids. Use recipes, magazines, photographs and hand drawn illustrations to enhance your presentation