Food Chemistry

What are the acids used to determine titratable acidity in the following foods: Orange Juice, Apple Juice, Yogurt, Grape Juice, Vinegar, Coca-cola, Peach Juice, Sprite, Grapefruit?

Orange Juice - citric; apple - malic; yogurt - lactic; grape - tartaric; vinegar - acetic; coke - phosphoric; peach - malic; sprite - citric; Grapefruit - citric acid.

List the 6 major classes of enzymes.

Oxidoreductases, transferase, ligase, lyase, isomerase, hydrolase

Give three classes of enzymes relevant to foods.

Oxidoreductases; Hydrolases; Lyases; Isomerases

Name three of the four cinnamic acid derivatives that are widely distributed in plants.

p-coumaric, caffeic, ferulic, and sinapic

What are the two equations for water activity?

P/Po ( partial vapor pressure of food moisture at T divided by saturation vapor pressure of water at T) and ERH/100 (equilibrium relative humidity at T divided by 100)

Give 3 factors that determine the stability of emulsions.

Particle size, pH of phases, type of emulsifier, size of globules, viscosity, interfacial tension, temperature

Rank in increasing water activity: Honey, bread, condensed milk, peanut butter

Peanut butter, honey, condensed milk, bread

Name 3 specific enzymes that act on pectic substances.

Pectin methylesterase, polygalacturonase, pectin lyase

What are the four factors that influence protein solubility?

pH/acidity, amino acid composition, ionic strength, temperature, molecular size

List three phytonutrients present in raisins that are associated with its health benefits.

Phenolic acids: caftaric and coutaric, flavonols: quercetin and kaemferol

Which phosphates are allowed in food?

Phosphoric acid, Sodium phosphates, Potassium phosphates, Calcium phosphates, Magnesium phosphates, Ammonium phosphates

What are the primary, secondary, tertiary, and quaternary structures?

Primary - amino acid sequence. Secondary - alpha-helix, beta sheet. Tertiary - one complete protein chain with cross bonds linking it together. Quaternary - four separate protein chains assembled as one.

Name and describe the four structures of protein.

Primary (amino acid sequence), secondary (local folding patterns like alpha-helices and beta-sheets), tertiary (overall 3D shape of a single polypeptide chain), and quaternary (arrangement of multiple polypeptide chains in a protein)

Name 3 factors influencing the consistency of commercial fats.

Proportion of solids in the fat, number, size, and kinds of crystals, viscosity of the liquid, temperature treatment, and mechanical working.

Name the significance of importance of the following enzymes. Rennet, papain, lactase, alkaline phosphatase

Rennet – curdle milk, papain – tenderize meat, lactase – converts lactose to monosaccharides, alkaline phosphatase – indicates milk pasteurization

Smoke point comparisons of oils: canola, grapeseed, sunflower, safflower, olive

Safflower (510), Canola (460), Sunflower (450), Grapeseed (420), Olive (410)

Name five polar amino acids.

Serine, threonine, cysteine, tyrosine, asparagine and glutamine.

What are the three major classes of lipids and give an example of each?

Simple lipids - acylglycerols, waxes; Compound lipids - phospholipids, cerebrosides, gangliosides; Derived lipids - carotenoids, steroids, fat-soluble vitamins.

List four main functional properties of egg protein.

Solubility, emulsification, foaming, gelling

Name four molecular characteristics of proteins desirable for film and foam formation.

Soluble; large; amphipathic; flexible domains; interactive regions; disposition of charged groups; retention of structure; and polar residues