Food Chemistry

What are the usual components of baking powder?

A carbonate (usually sodium bicarbonate) and an acid.

What happens to a catalyst in a chemical reaction?

A catalyst can increase the rate of a reaction but the catalyst itself remains unchanged

What is a chemical leavening system, and what are the two essential components of a chemical leavening system?

A Chemical leavening system is a system of controlled carbon dioxide release to give rise to baked products, the two components are a leavening agent. sodium bicarbonate) and acidic agent

What is protopectin?

A component of cementing material between plant cell wall. In fruits, it is converted to pectin as fruit matures.

What is case hardening?

A condition in drying where outer cells collapse to form a water-impenetrable layer, making rehydration difficult.

What is the definition of a saturated fatty acid?

A fatty acid with no double bonds on the alkyl chain.

What type of emulsion is foam?

A gas-in-liquid emulsion or air-in-water emulsion

What is the definition of a gel?

A liquid dispersed in a solid.

In order for a liquid to foam it must have:

A low surface tension

At what pH can a food be called a low acid food?

A pH greater than 4.6

What is a conjugated protein?

A protein with chemical components, in addition to amino acids (examples: lipoproteins and metalloproteins)

What is an emulsion?

A system containing 2 immiscible liquids

With regard to protein gelation, define thermally irreversible gel and thermally reversible gel. Give the predominant type of inter protein bonding and an example of food gels in each classification

A thermally reversible gel forms upon cooling after heating; hydrogen bonding is primary; gelatin is an example. A thermally irreversible gel forms during heating; covalent (disulfides) is primary bonding; examples include egg white, whey protein, soy protein, etc.

Differentiate between a gas and a vapor at room temp.

A vapor is the gaseous state of a substance which is normally liquid at room temp. A gas is a substance with a boiling point below room temp

What is the name when its negative 273 degrees C?

Absolute zero

What is the difference between accuracy and precision

Accuracy is how close the experimental value is to the true value, precision is how close experimental values are to themselves

The preserving activity of vinegar has been known from ancient time. The active component is

Acetic Acid

What is the major acid found in vinegar?

Acetic acid.

What color are anthocyanins at acidic pH and basic pH?

Acidic=red, basic=blue or yellow

What compound is formed when glycerol is heated?

Acrolein