NDFS 250 Exam 3

What are the functions of fat in food?

Flavor, emulsify, satiety, flaky texture, transfer heat, leaven, prevent sticking

Butyric acid

4:0

Lauric acid

12:0

Palmitic acid

16:0

Palmitoleic acid

16:1

Stearic acid

18:0

Oleic acid

18:1

Linoleic acid

18:1

Linoleic acid

18:2

Linolenic acid

18:3

Describe a triglyceride

Glycerol backbone (C-C-C), fatty acid (ROOH)

How are triglycerides formed?

esterification

Glycerol + acid = mono glycerine + water

Cis fats

Double bonds, curved structure

Trans fats

Double bonds, straight structure

Omega-3 fat

Double bond at 3rd Carib from methyl end

How are trans fats formed?

partial hydrogenation

How does chain length affect melting point?

the longer the chain, the higher the melting point because of more interaction points

How does saturation affect melting point?

Greater unsaturation, the lower the melting point

Define plasticity

The ability to be moldable and still hold shape

What is hydrogenation

The process of converting unsaturated fats to saturated fats by adding hydrogen

What is interesterification

Heat and a catalyst to fats make it more homogenous, smaller crystals and higher quality

Define emulsion

Mixtures of water and fat/oil

2 examples of emulsions

Oil in water (mayonnaise), water in oil (margarine)

Explain emulsion formation

Energy and emulsifiers are needed

How do emulsions work?

Molecules have polar and nonpolar regions on 1 molecule

Natural emulsifying agents

Proteins, solid particles, phospholipids

Example of protein emulsifier

Hydrophilic and hydrophobic amino acids

Example of solid particle emulsifiers

Spices (usually temporary)

Example of phospholipid emulsifier

Lecithin in eggs

Synthetic emulsifying agents

Fatty acid esters, monoglycerides, diglycerides

3 types of emulsion instability

Coalescence, creaming, inversion

Coalescence

Merging of droplets

Creaming

Separation into 2 phases

Inversion

O/W to W/O

2 causes of emulsion instability

Film integrity (pH, agitation), droplet movement (heat, viscosity)

Describe egg white foams

Protein denatures, egg proteins surround air, hydrophobic towards air

What happens if you beat egg whites too much?

Dry, denatured proteins interact

What happens if you beat egg whites too little?

Transparent, not enough denaturing of proteins

How are whipped cream foams supported?

Cold temps, fat globules disrupted

State the order of relative sweetness and solubility of sugars

Fructose, sucrose, glucose, maltose, galactose, lactose

2 types of non enzymatic browning

caramelization and mallard reaction

Caramelization example and formation

Peanut brittle, no protein involved. Carb + dry heat (no moisture)

Maillard reaction example and formation

Bread/meat/caramels, includes protein, C=O + NH2

Define invert sugar

Sucrose broken into glucose and fructose by invertase or acid & heat

2 functions of invert sugar

Attracts more water, prevents crystallization

2 confection classifications

Crystalline, amorphous (chewy/hard)

Crystalline confection examples

Fudge, rock candy, fondant

Chewy amorphous confection example

Taffy, caramel

Amorphous hard confection example

Brittle, lollipop, butterscotch

What factors affect sucrose crystallization rate?

Temperature,concentration, agitation, interfering agents, seeding

How is sucrose crystallization prevented in crystalline confections?

Stirring while cold

How is sucrose crystallization prevented in non-crystalline confections?

Quick cooling

What are the 2 tests for candy doneness?

Boiling point, cold water test

Boiling point test

measures concentration of solutes in the syrup (objective)

Cold water test

Measures consistency, subjective

Define batter

Beaten, stirred, more water:flour

Define dough

Kneaded, less water:flour

Define gluten

Water insoluble protein complex with gluten in and gliadin

Define gliadin

fluid and sticky

Define glutenin

Elastic

How is gluten developed?

Hydration and physical manipulation

3 types of leavening gases

Air, steam, CO2

How is air incorporated into food?

Physically (beating, creaming, folding, whipping)

How is steam incorporated into food ?

Heat, water to steam

How is CO2 incorporated into food?

Chemical/biological reactions (baking powder/soda, yeast, bacteria)

Write the general reaction of baking soda with acid

NaHCO3 + H+ —> Na+ + H2CO3 + H2O + CO2

State the defects in baked goods containing too much baking soda

Too alkaline, soapy, color spots

State the defects in baked goods containing too little baking soda

Soggy, compact, whitened

State the ingredients of baking powder

25% baking soda, 25% starch, 25% dry acids

What is the action of slow acting acids?

Requires HEAT, is not soluble

What is a compound used as a slow acting acid?

sodium aluminum sulfate

What is the action of fast acting acids?

High soluble, does not require heat (can be done at room temperature)

What is a compound used as a fast acting acid?

Monocalcium phosphate monohydrate

What is the genus and species of yeast used in baked products?

Saccharomyces cerevisiae

What is the reaction of CO2 production via yeast

glucose --> ethanol + 2CO2

What are the 7 ingredients common to a baked product?

Flour, liquid, leavening agent, eggs, fat, salt, sugar

Flour function in baked products

Structure

Liquid function in baked products

hydration, steam, dissolver

Leavening agent function in baked products

texture

Eggs function in baked products

binding, emulsification

Fat function in baked products

Tenderness

Salt function in baked products

taste, leavening

Sugar function in baked products

taste, tenderness

3 purposes of manipulating ingredients in baked goods

distribute leavening, fat, and liquid

What factors affect optimum manipulation?

over/undermixing impacts gluten development

Define creaming

work sugar crystals into fat using air

Define cutting

Subdivide fat into flour (for layers)

Define folding

Gently incorporating 1 ingredient into another

Define kneading

stretch, fold, press dough to form gluten strands

Define whipping

Beating to add air

What are the essential ingredients in yeast bread?

Yeast, water, flour, salt

What steps are required for the straight dough method of manipulating yeast dough?

Punch step and proof step

What is the purpose of the punch step?

Gluten not overstretched, redistributes nutrients for yeast

What is the purpose of the proof step?

Allows for a 2nd rise, pH changes cause gluten changes

What is the muffin method of mixing?

Dry & liquids are mixed separately,

What is a quick bread?

no yeast, leavening is quick

Why is the muffin method used?

Gives the product enough gluten, but not too much to be tough. It also prevents tunnelling

How must cake ingredients be balanced?

Liquid (flour, egg) & dry (fat, sugar) ingredients are in equal proportions

How can a uniform texture be reached in shortened cake?

Creaming allows for more air pockets and an emulsifier evenly distributes the fat