The Art & Science of Homemade Ice Cream

Summertime and Ice Cream together so we thought it’d be fun to let readers learn from the master ice cream maker himself.  But first a little background.

Dairy Processing Education at the Ontario Agricultural College, University of Guelph, has been part of our mandate for nearly 140 years. The Department of Food Science is proud to be able to use the internet to continue this long-standing tradition. Ice Cream in all its history and folklore has been a focus since William Neilson’s son and wife attended the course and figured out that bricks of ice cream would fit nicely into the small ice boxes that most homes had at the time.

Professor Doug Goff who is the on-campus ice cream expert teaches the course and has kindly allowed Food Day Canada to share the recipe. “The following information comes from a publication developed by the late Professor A. M. Pearson of the University of Guelph, targeted to the manufacture of ice cream in the home with an old-fashioned hand or electric crank bucket, cooled by ice and salt.” But electric freezers work well, too.

About the Ingredients

The main constituents of ice cream are fat, milk solids-not-fat (skim-milk powder), sugar, gelatin (or other suitable stabilizer), egg and flavouring.

A variety of milk products can be used: cream, whole milk, condensed milk and instant skim-milk powder. The recipes stated below proved satisfactory using whipping cream (32-35% fat), table cream (18% fat) and whole milk. The fat gives the product richness, smoothness and flavour. Skim-milk powder is used to increase the solids content of the ice cream and give it more body. It is also an important source of protein which will improve the ice cream nutritionally. Use good quality, fresh powder to avoid imparting a stale flavour to the ice cream.

Liquid coffee whitener (usually purchased frozen) is a cream substitute in one of the recipes. It will yield a slightly different flavour which is still very acceptable. The texture of the ice cream is very creamy. Liquid coffee whitener offers the convenience of being stored frozen in your freezer and is readily available if a quick decision is made to make ice cream.

Sugar is a common ingredient to use as a sweetener. It increases the palatability and improves the body and texture.

The next ingredient, gelatin (or similar substance) assists in absorbing some of the free water in the ice cream mix and helps prevent the formation of large crystals in the ice cream.It also gives substance or a less watery taste when the ice cream is consumed. The eggs are added to make the fat and water more miscible and also to improve the whipping ability which gives the ice cream greater resistance to melting.

Although vanilla is the flavour added to all of the mixes listed below, you may add flavours to suit you taste.

mL The yield from the recipes listed below should be three to four litres.

Premium Vanilla Ice Cream

2 litres table cream  (18%)
350 mL instant skim-milk powder
450 mL sugar
7 g gelatin
1  egg
10 mL vanilla
Calories per 100 g 230

Lower Fat Vanilla Ice Cream

2 litres whole milk (3.5%)
500 mL instant skim-milk powder 500 ml (2 cups)
350 mL sugar
7 g gelatin
1 egg
10 mL vanilla
Calories per 100 g 125

Preparation

The mix (unfrozen ice cream) has to be cooked (pasteurized). For pasteurizing the mix, it is best to use a double boiler to prevent scorching.

Place the liquid ingredients (milk, cream or coffee whitener) in the upper section of the double boiler. Beat in the eggs and the skim-milk powder. Mix the gelatin with the sugar and add to the liquid with constant mixing. While stirring, heat to about 70oC. Place the container in cold water and cool as rapidly as possible to below 18oC.

The ice cream mix is best if it is aged (stored in the refrigerator) overnight. This improves the whipping qualities of the mix and the body and texture of the ice cream. If time does not permit overnight aging, let the mix stand in the refrigerator for at least four hours. After the aging process is completed, remove the mix from the refrigerator and stir in the flavouring.

Freezing the Ice Cream

The freezing procedure has a two-fold purpose, the removal of heat from the mix and the incorporation of air into the mix. Heat is removed by conduction through the metal to the salt water brine surrounding the freezing can. This transfer of heat depends upon the temperature of the brine, the speed of the dasher and how well the dasher scrapes the cold mix from the surface of the freezer can. The dasher speed and surface contact are important to achieve complete removal of the frozen ice cream from the wall of the freezer can. A brine made from 500 grams (1 lb.) of salt and 5 kilograms (11 lbs.) of crushed ice (one pail full) makes a good freezing mixture.

Before starting to freeze the ice cream, make sure all parts of the freezer coming in contact with the ice cream are clean and have been scalded. Let the can cool before pouring in the mix. Place the empty can in the freezer bucket and insert the dasher ensuring both the can and the dasher are centred. Pour the cold, aged mix into the freezer can. The can should not be filled over two-thirds full to allow sufficient room for air incorporation.

The recipes listed below will fill a 5 litre freezer can to just below the fill line. Attach the motor or crank mechanism, depending on whether your freezer is the electric or hand-cranked style, and latch down securely. Plug in the motor or start turning the crank. Immediately begin adding crushed ice around the can sprinkling it generously with salt. Try to add the salt and ice in the same one to ten proportion to get the proper brine temperature. After the bucket is filled with ice to the overflow hole, pour a little water over the ice to aid in the melting process.

Freeze the mix for 20 to 30 minutes. If the electric motor stalls, immediately unplug it. Remove the motor or crank and take the dasher out of the ice cream. The ice cream will be softly frozen. Scrape the ice cream from the dasher and either scoop into suitable containers or pack in the freezer can. Immediately place the ice cream in the deep freeze to harden.

If freezer facilities are not available, the ice cream can be left in the can, the lid plugged with a cork and placed back into the bucket. Repack the freezer with more ice and salt, cover with a heavy towel and set in a cool place to harden until serving time. This will require further addition of ice and salt depending on the length of time the ice cream is being held.

A Series of Old-fashioned Hints (a.k.a. trouble-shooting)

  1.  If the ice cream is very soft, the brine is not cold enough. More salt should be added to reduce the brine temperature.
  2. If the ice cream is coarse and ice in less than 20 minutes, the brine has become to too cold too quickly. Too much salt has been used.
  3. Make the ice cream mix the day before it is frozen to get a smoother product and a higher yield.
  4. Electric freezing takes longer than hand operated.
  5. Use crushed ice for freezing.
  6. Freeze at least 3 hours before the ice cream is to be served.
  7. Be sure dasher is properly centred in the freezer can.
  8. Add liquid flavours before freezing but if you want to add fruits or nuts, add them after freezing and before hardening.
  9. Use a wire whip to blend ingredients for best results.
  10. Clean the salt off all the metal parts of the freezer to prevent corrosion.
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