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Micrometer ice crystals-Dr. Wang

Ice cream is a complex food--H.D. Goff. It can be classified as foam or dispersion or emulsion. The smoothness and perceived quality of an ice cream depends in large part on the small size of ice crystals (Cook and Hartel, 2010).
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Greg is explaining how Pacojet ($4000 ice cream machine) works.
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Greg in action.
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The same ice cream base was 'frozen' in three different ways. The base placed in freezer was hard and icy cold!
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Made with ice cream maker tasted like a regular good ice cream!
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Made with liquid N2 was so smooth and creamy!
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Fierce Caramel Corn

Caramel Corn (adapted from Karen Demasco ).


2 Heatproof Spatulas
8 qt Stockpot with lid
Large Mixing Bowl
4 qt Saucepot
Wooden Spoon
Pastry Brush (with container of clean cold water)
Medium Whisk
2 Large Sheet Trays, lined with parchment paper


AN Non-stick cooking spray
3 T Vegetable oil
½ c Popcorn Kernels
1 ½ t Baking Soda
3 c Granulated Sugar
1 ½ T Kosher Salt
1 ½ oz Unsalted Butter, cold, cut into small pieces
1 c Water


1. Spray the two heatproof spatulas and mixing bowl with the nonstick cooking spray.
2. Add vegetable oil to 8 qt stockpot, and heat gently over medium-high heat. Add one popcorn kernel.
3. When kernel pops, add remaining kernels and recover with lid. Continue to cook over medium-high heat, shaking continuously.
4. Remove pot from heat when popping slows to near stopping point, and pour into the prepared large mixing bowl.
5. Measure baking soda into small receptacle and keep at hand.
6. Combine sugar, salt, butter, and water in saucepot.
7. Stir with wooden spoon to immerse sugar into water.
8. Brush down interior walls of sauce pot with clean wet pastry brush
9. Place pot on stove over high heat until a boil is attained. Reduce heat to medium.
10. Cook without stirring until all sugar melts and turns a light golden color.
11. Remove from heat.
12. Add baking soda and whisk thoroughly. Caramel will bubble vigorously and may boil over. Do this step over the sink or a separate sheet tray, just in case.
13. Once baking soda is fully incorporated, pour over popcorn in bowl, using only that which comes out of pot easily. Do not scrape pot to get remaining caramel in to popcorn.
14. Using the sprayed spatulas, toss the caramel and popcorn to coat thoroughly and evenly.
15. Pour onto parchment paper lined sheet trays in one flat layer. Allow to cool.
16. When cool, break in to clusters by hand.
17. Store in airtight container

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Fierce! Peanut Butter Powder


Food Processor
Digital Balance
Rubber Spatula
Tamis or Mesh Strainer

75g Peanut butter
50g Tapioca Maltodextrin (N-Zorbit)

1. Place peanut butter in bowl of food processor. Cover and process to spread out.
2. Add maltodextrin. Pulse processor briefly to incorporate and prevent blowout.
3. Once mixed, process continually until product reaches fluffy powder consistency. Additional maltodextrin may be required, add as needed to achieve desired effect.
4. Remove contents from food processor and pass through a tamis or strainer for lighter fluffier consistency.
5. Store in airtight container.

Fierce Sweet Corn Ice Cream Recipe

Recipe (adapted from Melissa Clarksweet corn ice cream and Chefsteps.com)) by Greg Esmond

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Cutting Board
Measuring Cups
2 qt pot
Fine mesh strainer
2 oz Ladle
Rubber spatula
Digital Balance
Vacuum Sealer
Vacuum Bag
Immersion Circulator and Water Bath set to 850C
Ice Bath
Stand mixer with Paddle Attachment
Liquid Nitrogen Dewar (or Styrofoam Cooler)
Liquid Nitrogen
Protective Gloves
Protective Eye Wear
Ice Cream Scoop


4 Ears fresh corn, husk and silk removed
1 ½ c Whole Milk
2 c Heavy Cream
¼ t Fine Sea Salt
225 g Granulated Sugar
6 ea Egg Yolks, Lg.


1. Using knife, remove corn kernels from corncob. Cut cob into thirds.
2. Place corn kernels, corncob, milk, heavy cream, and salt in 2 qt pot.
3. Bring mixture to a boil, stirring occasionally with rubber spatula to prevent burning. Remove from heat and allow to stand for one hour to steep.
4. Remove corncobs, and pour remaining ingredients into pitcher of blender.
5. Blend mixture until relatively smooth. (Alternatively an immersion blender may be used for steps 4 and 5)
6. Strain mixture through fine mesh strainer into mixing bowl. Press on solids in strainer with back of ladle to extract maximum flavor. Discard solids.
7. Cool mixture to 40C by placing bowl with mixture inside a larger bowl filled with ice water (ice bath).
8. When appropriately cooled, place corn/cream/milk mixture into pitcher of blender. Begin blending over low speed.
9. While blender is running, add sugar followed by egg yolks. Blend to homogenous mixture.
10. Pour mixture into vacuum sealing bag.
11. Seal on medium vacuum, high seal. Remove all plates inside chamber to help prevent spilling before vacuuming and sealing.
12. Place bag of ice cream base into preheated 850C water bath.
13. Cook for 1 hour at 850C, agitating bag gently occasionally during cooking.
14. Remove bag from water bath, and place in ice bath to cool completely.
15. When cold, open bag and strain through fine mesh strainer.
16. Pour strained mixture into bowl of stand mixer.
17. Turn on to medium speed
19. Stop to check progress periodically. Scrape down sides as needed with rubber spatula (or alternatively use blow torch while mixer is on to loosen hardened areas along outside of bowl).
20. When desired texture is reached, serve immediately or transfer to labeled appropriate container and store in freezer.

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Introduction of Sweet Corn/Maize: Early civilizations of the Americas were supported by corn/maize. The Incas of Peru, the Mayas and Aztecs of Mexico, the cliff dwellers of Mesa Verde, CO, the Cahokia mound builders of IL, and the Mississippians of Arkansas depended on corn as a dietary staple. Sweet corn cultivated by early Americans carried a mutation in the gene (Su1) that resulted in deficiency in a starch-debranching enzyme called isoamylase (http://www.maizegenetics.net/sweet-corn) (Pan and Nelson, 1984 Plant Physiol 74(2):324). Because sweet corn cannot convert sugar to starch, sweet corn stores more sucrose than water-insoluble starch in endosperm. The mutation also resulted in a higher concentration of highly branched phytoglycogen that gave sweet corn its creamy texture. Modern sweet corn varieties carry instead a mutation in either the shrunken2 gene (sh2) or the brittle endosperm2 (bt2) gene. The mutation in sh2 or bt2 results in deficiency of the large or small subunits of ADP-glucose pyrophosphorylase, respectively. ADP-glucose pyrophosphorylase converts ADP-glucose into glucose-1-phosphate, which is the substrate for starch synthases (Bae, 1990, Maydica, 35, 317; Bhave, 1990 Plant Cell 2, 581).

About the recipe

Preparing the Mix: Corn flavor and water-soluble sugar molecules are extracted into milk/cream at steps 3, 5 and 6. This French-style ice cream contains egg yolks. Proteins and emulsifiers in the yolk help keep ice crystals small, resulting in very smooth ice cream (McGee, On Food and Cooking, p41). Egg yolk consists of 68% low-density lipoproteins (LDL), 16% high-density lipoproteins (HDL), 10% livetins and 4% phosvitins (McCully, Mok & Common, 1962, Canadian Journal of Biochemistry and Physiology, 40, pp. 937–952). All the components of the yolk adsorb at the oil–water interface and form films around oil droplets.

Step 9 disperses fat droplets evenly so that the mixture will have a higher capacity to hold onto air. In step 12, the French-style ice cream base is cooked to disperse the proteins and emulsifiers. Sous vide cooking denatures proteins, especially LDL, in order to form a network that is thought to improve body and texture. LDL starts to denature at 70°C. Cooking also distributes emulsifiers found in egg yolk in order to stabilize the water-fat interface. The end result is a thickened, custard-like mix. Chef Greg used the sous-vide method for precise control of the cooking temperature so that custard cooked evenly without forming clumps. Alternatively, custard can be made on a stovetop cooker by carefully controlling the temperature and rapidly whisking the base.

Freezing: The size of ice crystals determines whether ice cream is coarse and granny or fine and smooth. Chef Greg used liquid N2 to freeze the mix as rapidly as possible. Liquid nitrogen can be used to immediately super-cool (lower the temperature below the freezing point without forming a solid) the mix within seconds. Super-cooling and stirring generates many ice nuclei. Nucleation is the initial process in crystallization, and formation of multiple nuclei results in smaller crystals and a creamier texture.
Ice creams consist of a successfully frozen heterogeneous composite of ice crystals, fat, sugar, air and non-fat milk solids. Scientists can’t decide whether to call ice cream an emulsion, a foam, or a colloid: “It is best described as structure of water-ice crystals, air bubbles, and milk-fat globules suspended in an fluid of sugar and milk proteins” (Robert Kunzig, Discovery 2004). “Electron microscopy picture of ice cream reveals a complex microstructure of ice crystals (about 30% by volume) and air bubbles (50%) held together by a viscous sugar solution (15%). Close inspection of the air bubbles shows some tiny features on their surface—these are fat droplets (5%)” (Clarke, Phys. Educ, 38 248).
While Chef Greg used sucrose, he could probably have used honey (fructose). It has been observed that monosaccharides such as fructose or glucose produce a much softer ice cream than disaccharides such as sucrose. The viscous sugar solution could also be in a glass state since the glass transition temperature of a supersaturated sugar solution is way above the liquid N2 temperature of -196°C/-321°F.
Smaller ice crystals and air bubbles yield a smoother, creamier ice cream. As time passes unfortunately, ice crystals and air bubbles tend to grow as large as possible. This occurs because larger crystals have lower surface area than smaller crystals, and larger air bubbles have smaller internal pressure than smaller bubbles. The result is an icy, crunchy, structure-less, and flat ice cream. Commercially made ice creams uses gelatin, agar, or xantham gum to stabilize emulsion/foam/colloid. This recipe doesn’t use stabilizers, so eat it right away! Bon appétit!