ICE CREAM:

WHAT IS ICE CREAM:

  • Must abide by its standard of identity (SOI)

    • By law

  • Food produced by freezing while stirring

    • Pasteurized mix consisting of dairy products

  • Contains not less than 10% milkfat and 20% milk solids

COMPONENTS OF ICE CREAM AND THEIR FUNCTIONS:

  • Types and grades of ice cream

    • Standard = overrun (vs. super premium and premium)

    • standard/philadelphia-style/new york = no egg or uses egg white

    • French vanilla/style = egg yolk used for emulsifier

    • Fat free = 0.5g fat or less per serving

    • Light = calories from fat is less than 33% total original calories

    • Low and reduced fat = 25% less fat than original

    • Gelato = higher fat and less overrun

    • Sherbet = stretched ice cream with fruit juice and some milk fat

    • Sorbet = no milk or cream, alcohol or wine can be added to reduce freezing temperature

  • Components

    • Water

    • Carbohydrates (lactose)

    • Fat (lipids)

    • protein 

    • Air

  • Standard of identity (SOI) of milk

    • “Milk is the lacteal secretion, practically free from colostrum obtained by the complete milking of one or more healthy cows.”

      • “Shall contain not less than 8.25 percent milk solids not fat and not less than 3.25 percent milkfat”

  • Composition of milk (average)

    • Water → 87%

    • Fat → 3-4%

    • protein → 3-3.5%

    • Carbohydrates (lactose) → 4-5%

    • Ash (minerals) → <1%

    • Milk solids non fat → 9%

      • Protein, sugars, minerals

    • Total solids → 12.9%

      • Calcium and magnesium

    • Same ingredients in ice cream act a nuclei

  • Freezing

    • Temperature of food is less than freezing point

    • Phase change from liquid to solid

    • Ice is a crystalline structure

    • Freezing point = lower than water

  • Ice crystals

    • Require nuclei to form

      • What are nuclei in ice cream

    • Factors influencing ice crystal formation number + size

      • Time 

      • Temperature

    • Want ice cream to freeze fast → smaller crystals

      • Smoother, creamier texture

      • Ultra low freezers (liquid nitrogen -121 celsius/-321 fahrenheit)

  • Carbohydrates

    • Lactose (main carbohydrate in milk) 

      • Sucrose

      • Glucose

      • Xanthan gum 

    • Functions in ice cream

      • Sweetness 

      • Nuclei for ice crystal formation

      • Keeping ice cream soft → prevents water to completely freeze

        • Too much sugar = too sweet, syrupy mess

        • Ideal = 15%

    • Decrease water activity of ice cream

  • Lipids

    • Fat in foods → mainly triacylglycerol

      • Glycerol

      • 3 fatty acids (tail)

  • Function of milk fat in ice cream

    • Source = milk, 29% triacylglycerol

    • Provide a “buttery” mouthfeel

    • Milk fats → made of various kinds of fats = wide range of melting temperatures

      • Slow melting in mouth

    • Build to aroma compounds

    • Hold air → keeps ice cream fluffy

    • Coat ice crystals to keep them from growing too big

  • Emulsions + Stabilizers

    • Milk = emulsions → so is ice cream

    • Emulsifiers + stabilizers = limit crystal growth to prevent icy texture

      • Too much decreases taste + makes ice cream gummy

    • Examples

      • Phospholipids (lecithin from soy or egg yolk)

      • Carrageenan

  • Protein

    • Milk = one of the big 9 allergens due to proteins

      • Casein proteins (curds) 

        • 80% of milk protein in cows

        • Retains shape during whipping

      • Whey protein (20%)

        • Shape held by weak bonds

        • Denatured by whipping ice cream → increases ability to hold air bubbles

    • Functionality in ice cream = foam stability

      • Air = critical

        • To create “foam” after whipping

        • Air pockets = trapped

        • Presence of air helps distribute ice crystals → makes it creamier

      • Milk proteins = help stabilize air pockets → induced by whipping

        • Align around air to prevent the bubbles from popping

      • Introduction of air = overrun