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Sour Grape Ice Cream 1 WRITTEN ASSIGNMENT: SOUR GRAPE ICE CREAM Ice cream is just ice, fat and air; the way these three main ingredients interact determines the ice cream quality. Color, texture and taste are the main quality factors for ice cream. To optimize these it is particularly important to control process parameters including the temperature and time of heating and cooling the mixture. Over-heating and slow cooling causes changes to the flavor and color of the milk, whereas under-heating may lead to survival of undesirable micro-organisms, risking food poisoning from the product.
The rate at which ice cream freezes can greatly affect final product texture by determining the size of the ice crystals in the product. It is desirable to have much smaller ice crystals and lower sized fat globules and air cells in its structure. To achieve this rapid heat transfer rates are needed. The major storage requirement for the ice cream is to minimize the number of times and the duration the ice cream is melted and frozen again that causes the development of grittiness in the product. Frozen dessert manufacturers face the challenge of delivering everybody’s favorite frozen treats with consistent taste, texture and quality.
The additives, which act as emulsifiers and stabilizers, are used to prevent heat shock and the formation of ice crystals during the production process. The most common additives are guar gum, extracted from the guar bush, and carrageenan, derived from sea kelp or Irish moss. Ice cream flavors have come a long way from the standard vanilla, strawberry, and chocolate. In an ever-expanding array of combinations, fruit purees and extracts, cocoa powder, nuts, cookie pieces, and cookie dough are blended into the ice cream mixture. Air is added to ice cream to improve its ability to absorb flavorings and to facilitate serving.
Without air, ice cream becomes heavy and soggy. On the other hand, too much air results in ice cream that is snowy and dry. The federal government allows ice cream to contain as much as 100% of its volume in air, known in the industry as overrun. Makers of high-quality ice cream such as sour grape use fresh whole dairy products, about 20% of air, between 16-20% butterfat, and as few additives as possible. The ice cream making process is a very detailed process which requires a great deal of attention to detail. Blending the mixture •The milk arrives at the ice cream plant in refrigerated tanker trucks from local dairy farms.
The milk is then pumped into 5,000 gal storage silos that are kept at 36°F. Pipes bring the milk in pre-measured amounts to 1,000 gal stainless steel blenders. Premeasured amounts of eggs, sugar, and additives are blended with the milk for six to eight minutes. Pasteurizing to kill bacteria •The blended mixture is piped to the pasteurization machine, which is composed of a series of thin stainless steel plates. Hot water, approximately 182°F, flows on one side of the plates. The cold milk mixture is piped through on the other side.
The water warms the mixture to a temperature of 180°F, effectively killing any existing bacteria. Homogenizing to produce a uniform texture •By the application of intensive air pressure, sometimes as much as 2,000 pounds per square inch, the hot mixture is forced through a small opening into the homogenizer. This breaks down the fat particles and prevents them from separating from the rest of the mixture. In the homogenizer, which is essentially a high-pressure piston pump, the mixture is further blended as it is drawn into the pump cylinder on the down stroke and then forced back out on the upstroke.
Cooling and resting to blend flavors •The mixture is piped back to the pasteurizer where cold water, approximately 34°F, flows on one side of the plates as the mixture passes on the opposite side. In this manner, the mixture is cooled to 36°F. Then the mixture is pumped to 5,000 gal tanks in a room set at 36°F, where it sits for four to eight hours to allow the ingredients to blend. Flavoring the ice cream •The ice cream is pumped to stainless steel vats, each holding up to 300 gal of mixture. Sour grape flavoring is then piped into the vats and blended thoroughly.
Freezing to soft-serve consistency •Now the mixture must be frozen. It is pumped into continuous freezers that can freeze up to 700 gal per hour. The temperature inside the freezers is kept at -40°F, using liquid ammonia as a freezing agent. While the ice cream is in the freezer, air is injected into it. When the mixture leaves the freezer, it has the consistency of soft-serve ice cream. Packaging and bundling the finished product •Automatic filling machines drop preprinted pint or half-gallon-sized cardboard cartons into holders.
The cartons are then filled with premeasured amounts of ice cream at the rate of 70-90 cartons per hour. The machine then places a lid on each cartons and pushes it onto a conveyer belt. The cartons move along the conveyer belt where they pass under a ink jet that spray-paints an expiration date and production code onto each carton. After the imprinting, the cartons move through the bundler, a heat tunnel that covers each cup with plastic shrink wrapping. Hardening •Before storage and shipping, the ice cream must be hardened to a temperature of -10°F.
The conveyer system moves the ice cream cartons to a tunnel set at -30°F. Constantly turning ceiling fans create a wind chill of -60°F. The cartons move slowly back and forth through the tunnel for two to three hours until the contents are rock solid. The cartons are then stored in refrigerated warehouses until they are shipped to retail outlets. Quality Control Every step of this product should be randomly tested during the production process to ensure a high quality product is being served. Reference: http://www. foodsci. uoguelph. ca/dairyedu/icmanu. html