F&C colloidal dispersions/foams

colloidal dispersions

two immiscible phases, one dispersed in the other

major type of colloidal dispersions in foods

emulsions, foams

emulsions makeup

oil+water

foam makeup

air+liquid

dispersed phase what happens

droplets or bubbles

continuous phase what happens

liquid sourrounding dispersed phase

emulsions

a fine dispersion of minute droplets of one liquid in another, not soluble or miscible

oil in water (O/W) what type of phase happens to each

oil = dispersed, water = continuous

water in oil (W/O) what type of phase happens to each

water = dispersed, oil = continuous

oil in water ex.

mayo, milk, salad dressings, cake batters

water in oil ex.

butter, margarine

hydrophilic head emulsifies in

water

hydrophobic tail emulsifies in

oil

how do you stabilize emulsions

surround droplets, prevent separation

stabilizing emulsions ex.

egg yolk (lecithin), casein, mono/disacyglycerols

emulsions definition

a mixture of two or more liquids that don't naturally mix, where tiny droplets of one liquid are suspended in another

temporary emulsion stabilizer and separation and ex.

unstable, separate quickly, need shaking, french/italian dressing

semipermanent emulsion stabilizer and separation rate and ex.

stabilized with gums/starches, slower separation, creamy dressings

permanent emulsion stabilizer, separation, ex

stabilized wiht emulsifier, rarely separates, mayo

mayo formation

oil added dropwise to vinegar + egg yolk + seasonings while beating

mayo emulsion process

emulsifier surrounds oil droplets = stable permanent emulsion

foams

air dispersed in liquid

foams formation

beating incorporates air = liquid forms thin film around bubbles

foam stability

depends on foaming agent forming strong film

protein foam ex.

egg whites, gelatin

example food foams

meringue, angel food cake, marshmallows

what food prevents stable protein foam

egg yolk

fat foam ex.

heavy whipping cream, whipped cream, ice cream

dispersed phase in foams =

air

what allows stable mixing

emulsifiers

foams require what two things

air, stabilizing agent (protein, fat)