Ice-cream production

There is more activity in dairy products than anywhere else in the food industry. Ice milk and fro2en yogurt, early leaders in the field, rose rapidly in sales then plummeted. Fat-free ice cream has been marketed, but final results are not yet available. Sales of these products have not cannibalized traditional ice cream (35). Standards for traditional ice cream call for a minimum of 10% butterfat. One fat-free ice cream product is prepared from nonfat milk (skim) and cellulose gum. Fat-free ice creams have encountered strong resistance in some segments of the retail trade. Retailers in Maine and New York, states with important dairy producing industries, refuse to sell such products (36). 

Dry Ice. Refrigeration of foodstuffs, especially ice cream, meat products, and frozen foods, is the principal use for soHd carbon dioxide. Dry ice is especially useful for chilling ice cream products because it can be easily sawed into thin slabs and leaves no Hquid residue upon evaporation. Cmshed dry ice may be mixed directly with other products without contaminating them and is widely used in the processing of substances that must be kept cold. Dry ice is mixed with molded substances that must be kept cold. For example, dry ice is mixed with molded mbber articles in a tumbling dmm to chill them sufficiently so that the thin flash or rind becomes brittle and breaks off. It is also used to chill golf-ball centers before winding. 

Soybean-based ice cream products, technologically feasible, are generally not in use because of flavor problems. An acceptable ice cream has been made by replacing 50% of the nonfat milk soHds with a dried soy protein isolate made up of cheese whey (21). Chocolate flavor has been widely used to mask the flavor of soybean proteins in ice cream (see Flavors and spices). 

A successful example is ice cream products that are sold from the freezer and consist of a wafer cone filled with ice cream. If the ice cream was left in contact with the cone the cone would become soft. This is solved by adding a chocolate-flavoured coating to the inside of the cone. 

Prolonged storage of ice cream and exposure to severe temperature fluctuation commonly causes shrinkage, which is a defect due to partial thawing and loss of moisture and air. An additional defect common to ice cream after prolonged storage is oxidized flavor, which is caused by autoxidation of milk fat. This defect is especially important in ice cream products that contain frozen or dried milk ingredients. 

Figure 11 Protein binding to fat globules in ice cream mix at various temperatures and after ice cream production (I.C.). The latter analyzed at 5°C after thawing ice cream at 0°C. Effect of hydrocolioid blend and emulsifier.

Flaxseed oil has been proposed to be a valuable ingredient for ice cream products (Hall and Schwarz, 2002). Flaxseed oil replaced between 10% and 25% of the milk fat in ice cream formulas has been investigated. The 25% flaxseed product exhibited an oil-like mouth feel however, the presence of... 

Condensed and evaporated milk Fluid milk and cream (prod.weight) Ice cream (product weight)... 

While a higher level of fat gives a rich impression of mouthfeel, the fat also diminishes the perception of an added flavour. Therefore, we may see a quicker expression of the added flavour in a reduced-fat ice-cream product, sherbet, sorbet or water ice. The flavouring dose level may be adjusted down in these products [9, 11]. 

Other uses of palm oil are in snack foods, biscuits, ice-creams, salad dressings, mayonnaise, and so on. Fat plays a key role in all the above food items and formulations using palm oil products essentially replace some of the oils used traditionally. Oil suitable for ice-creams should be partly solid at 5°C and at —5°C, substantially liquid at 37°C, and have good melt feel characteristics. Palm oil, with a similar solid fat content profile to butterfat, is one such oil with suitable characteristics for ice-cream formulations. Palmkemel oil is also much used in ice cream products. 

To describe the science of ice cream, it is first necessary to describe some of the physical chemistry and colloid science that underpins it these are laid out in Chapter 2. Chapters 3 and 4 cover the ingredients and the ice cream making process respectively. Chapter 5 focuses on the production of various types of ice cream product. The physical and sensory measurements used to quantify and describe it are discussed in Chapter 6, and the micro structure, and its relationship to the texture, is examined in Chapter 7. Finally, Chapter 8 describes a number of... 

Two factors that have a major effect on the sales of ice cream products are the weather and advertising. Ice cream sales in the UK are very seasonal, peaking in the summer. In France, 65% of sales are made between June and September, and in Italy the average consumption... 

The ingredients of ice cream products can be classified in three groups ... 

The distinction between fats and oils is that the former are solid at room temperature, and the latter are liquid. Ice cream typically has a fat content of 8-10% by weight, though in premium ice creams it can be as high as 15-20%. Fat performs several functions in ice cream it helps to stabilize the foam, it is largely responsible for the creamy texture, it slows down the rate at which ice cream melts and it is necessary to deliver flavour molecules that are soluble in fat but not water. The major sources of fat used in industrial ice cream production are butterfat, cream and vegetable fat. 

An essential requirement of ice cream products is that they taste appealing. The flavours used in ice cream manufacture are usually supplied as solutions of aroma and taste compounds. Some flavour molecules are fat soluble, whereas others are water soluble. This affects the perception of flavour in ice cream water-soluble flavours are present in the matrix and are released rapidly on consumption, whereas fat-soluble flavours are released more slowly. Flavours may be natural, i.e. extracted from sources such as plants, or synthetic. The latter can be nature identical (artificially produced but identical to the naturally occurring form) or artificial (artificially produced and not occurring in nature). They are used to impart flavour to products, to enhance inherent flavours and to ensure uniformity of flavour between batches. Fruit acids, such as citric or malic acid are added to fruit flavoured water ice products to give them extra bite , by making them sour. The three most important ice cream flavours are vanilla, chocolate and strawberry. 

Fruit is used in ice cream products, either as fruit pieces, or as a sauce. Fruit pieces add novelty to ice cream products and enhance the perception of healthiness. Sauces, often fruit, but also chocolate and toffee, are widely used as toppings on cone and cup products or as ripples in ice cream. They provide flavour and texture contrast as well as an attractive product appearance. A wide range of fruits is used in ice cream products, from common European fruits such as strawberry and apple, to tropical fruits such as mango and banana. 

Nut pieces are added to ice cream products to provide texture contrast, flavour and visual appeal. Several types of nuts are used, for example almonds, cashews, hazelnuts, peanuts, pecans, pistachios and walnuts. Walnuts and pecans are often candied to create a crisper texture and darker colour. In the candying process, the nuts are mixed with sugar and then cooked at about 115 C. Nut pastes can be used as flavourings. Nut ingredients are generally expensive. Since some people are allergic to nuts control systems must be put in place to ensure that nuts cannot enter products on which they are not declared as ingredients. 

Chocolate and couvertures are dispersions of small (10-25 im) particles of sugar, and, depending on the type of chocolate, cocoa powder solids and non-fat milk solids, in a continuous fat phase. A layer of emulsifier (usually lecithin) is strongly adsorbed to the surface of the sugar particles. Chocolates and couvertures for ice cream products generally have higher fat contents (40-60%) than their normal ambient counterparts (28-35%). This is because chocolate on ice cream products is eaten at lower temperatures than ambient chocolate. An ambient chocolate would be very hard at —18 °C, and would have a waxy texture when eaten in conjunction with ice cream, because the mouth would be too cold to melt the fat in the chocolate. 

The packaging is an essential part of an ice cream product, as it both protects and helps to sell it. Packaging may take place during and/or after product assembly, depending on the product. There may be more than one layer of packaging - for example wrapped stick products are packaged in boxes with, for example, 24 or 48 products per box (the second layer), which are then stacked onto a pallet and shrink-wrapped (the third layer). The second and third layers are removed after distribution, so that the consumer usually only sees the first layer. The choice of material and structure of packaging is determined by several considerations. 

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