Chemical/physical changes in food

Acidic

• Turns food brown and creates pleasant, volatile, aromatic compounds. It is a reaction between amino acids in protein and sugar or starch. It begins at 154°C.

• Occurs when a starch is exposed to dry heat; the starch is broken down into dextrin, resulting in a change in colour to golden brown.

• A mixture with a pH between 8 and 14.

• A mixture with a pH between 1 and 6.

Alkalis

• A gelatinised mixture is allowed to stand for a period of time, allowing the gel structure to tighten and cause a ‘weeping’ effect. This may also occur with over coagulation.

• A mixture with a pH between 1 and 6.

• A mixture with a pH between 8 and 14.

• Starch granules absorb liquid in the presence of heat and thicken the liquid, forming a gel.

Caramelisation

• This process occurs when a supersaturated sugar solution is boiled, and large crystals are formed.

• Occurs when a starch is exposed to dry heat; the starch is broken down into dextrin, resulting in a change in colour to golden brown.

• Turns food brown and creates pleasant, volatile, aromatic compounds. It is a reaction between amino acids in protein and sugar or starch. It begins at 154°C.

• The process that sugars undergo when heated to high temperatures to develop a golden-brown colour

Coagulation

• A gelatinised mixture is allowed to stand for a period of time, allowing the gel structure to tighten and cause a ‘weeping’ effect. This may also occur with over coagulation.

• A permanent change in the protein from a liquid into a thick mass as a result of heat or the addition of acids. The denatured proteins form a new structure that retains water – a semi liquid becomes firm and maintains shape.

• The process of incorporating air into food products to increase volume and create a light, airy texture.

• Turns food brown and creates pleasant, volatile, aromatic compounds. It is a reaction between amino acids in protein and sugar or starch. It begins at 154°C.

Dextrinisation

• The process that sugars undergo when heated to high temperatures to develop a golden-brown colour

• The process of incorporating air into food products to increase volume and create a light, airy texture.

• Starch granules absorb liquid in the presence of heat and thicken the liquid, forming a gel.

• The process that occurs when a starch is exposed to dry heat; the starch is broken down to dextrin, resulting in a change in colour to golden brown

Gelatinisation

• A gelatinised mixture is allowed to stand for a period of time, allowing the gel structure to tighten and cause a ‘weeping’ effect. This may also occur with over coagulation.

• Starch granules absorb liquid in the presence of heat and thicken the liquid, forming a gel.

• Occurs when a starch is exposed to dry heat; the starch is broken down into dextrin, resulting in a change in colour to golden brown.

• The process of incorporating air into food products to increase volume and create a light, airy texture.

Maillard reaction

• Turns food brown and creates pleasant volatile aromatic compounds. It is a reaction between amino acids in protein and sugars and/or starch. It begins at about 154 °C, so can be seen when sautéing on the cooktop or baking in the oven.

• The permanent structural change of the protein molecules in food, with a weakening or breaking of the bonds between. This can occur with the application of heat, mechanical action or the addition of acids.

• Process when sugar (sucrose) begins to decompose when exposed to high temperatures (190°C) using dry heat. Hundreds of compounds are generated as the sugar decomposes, resulting in browning and enjoyable aromas.

• Occurs when a starch is exposed to dry heat; the starch is broken down into dextrin, resulting in a change in colour to golden brown.

Denaturisation

• A permanent change in the protein from a liquid into a thick mass as a result of heat or the addition of acids. The denatured proteins form a new structure that retains water – a semi liquid becomes firm and maintains shape.

• The permanent structural change of the protein molecules in food. This can occur with the application of heat, mechanical action or the addition of acids.

• Turns food brown and creates pleasant, volatile, aromatic compounds. It is a reaction between amino acids in protein and sugar or starch. It begins at 154°C.

• The process that sugars undergo when heated to high temperatures to develop a golden-brown colour

Emulsification

• Starch granules absorb liquid in the presence of heat and thicken the liquid, forming a gel.

• Mixing two liquids that don’t normally combine evenly; for example, water and oil

• The process of incorporating air into food products to increase volume and create a light, airy texture.

• A gelatinised mixture is allowed to stand for a period of time, allowing the gel structure to tighten and cause a ‘weeping’ effect. This may also occur with over coagulation.

Aeration

• Occurs when a starch is exposed to dry heat; the starch is broken down into dextrin, resulting in a change in colour to golden brown.

• This process occurs when a supersaturated sugar solution is boiled, and large crystals are formed.

• Turns food brown and creates pleasant, volatile, aromatic compounds. It is a reaction between amino acids in protein and sugar or starch. It begins at 154°C.

• The process of incorporating air into food products to increase volume and create a light, airy texture. This can be due to biological, chemical or mechanical actions