Week 2 Food Composition and Function

What is a chemical reaction?

process in which one or more substances, the reactants, are converted to one or more difference substances, the products; involve rearrangements in the connections (bonding) between atoms

What are popular reactions in food chemistry?

maillard reaction, caramelization, enzymatic browning, lipid oxidation, carbohydrate hydrolysis, fermentations, sugar isomerization

What do chemical reactions often involve?

heat production/absorption, gas/precipitate production, changes in color

What remains constant during a chemical reaction? 

mass of all chemicals remain the same because the number and type of atoms do not change 

What do chemical reactions need to be?

balanced, the number of each element in both sides of the equation need to be the same; balance everything else other than O and H first 

What is stoichiometry?

the relationship between the relative quantities of a substance taking part in a reaction or forming a compound, typically a ration of whole integers 

What is a solution?

mixture of solute(ex glucose) and solvent(ex water)

What is concentration?

how much of a compound is present per unit volume; dependent on the amount of solute disolved in solvent

What is molarity?

moles of a compound per liter of solution

What is mass percentage (w/w%)?

compound mass/solution mass *100; ex a sucrose solution 8w/w means that for a total of 100g of sucrose solution 8 of those grams are sucrose and the rest is water

What equation is used for dilution?

m1v1=m2v2

What do thermodynamic help us understand in food?

reactions between food ingredients, heat transfer, refrigeration, water activity

What food teqniques are based on thermodynamics? 

thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) 

What are the first two laws of thermodynamics?

energy is not created or destroyed, entropy (disorder) of the universe is always increasing 

What is an exothermic reaction?

release energy into the environment, -

What is an endothermic reaction?

absorb energy from the environment, +

When is a reaction spontaneous?

When delta G is negative

When is a reaction nonspontaneous?

When delta G is positive

What is collision theory?

for a chemical reaction to occur the reacting substances must collide with one another and the rate of the reaction depends on the frequency of collisions 

What must collisions be in order for the reaction to occur?

collide with sufficient energy higher than the activation energy

What is a catalyst? 

lowers activation energy thus more collision will lead to reactions 

What does temperate do to number of collisions? 

increases since particles have higher KE