Ice-CreamBooklet No. 285

Dairy Management And Milk Products: DMMPS-15ContentsPreface I. Introduction ll. Types III. Ingredients and composition

A. Dairy products B. Sweetening agents C. Fruits and nuts D. Additives E. Equipments F. Average composition

IV. Role of the Constituents V. Manufacturing Methods

Preface

Ice-cream is a very popular frozen confectionary dairy product consumed in India and other countries as well. Ice- cream is a mixture of cream, sugar and flavouring converted into a semi solid porous frozen mass by mixing in a freezer. The quality of ice cream is determined by its raw materials, composition, body and texture, flavouring and colouring, processing and storage. This booklet deals with all these aspects of ice-cream in detail.

Dr. K.T. Chandy, Agricultural & Environmental Education

I. Introduction

There is a growing world-wide market for frozen dairy products and frozen confectionary. A good profit can be realized by breaking into the ice-cream novelty market. Today the ice-cream may be considered a luxury food item although its popularity is increasing rapidly.

Ice-cream is a popular milk-product. This is prepared by mixing cream and milk in different proportions. About 0.3 percent of the total milk produced in India is utilized for ice- cream making. The demand for ice-cream has recently increased a great deal in towns and cities.

The quality of ice-cream is determined by its raw materials, composition, body and texture, flavouring and colouring, processing, and storage.

The body and texture of ice-cream made from buffalo milk may be slightly better than that of cow milk. Ice-cream may be defined as a frozen dairy product made by suitable blending and processing of cream and other milk products, together with sugar and flavour, with or without stabilizer or colour, and with the incorporation of air during the freezing process.

It may contain permitted stabilizers and emulsifiers not exceeding 0.5 % by weight. The product should contain not less than 10% milk fat, 3.5 % protein and 36.0 % total solids. Starch may be added to a maximum extent of 5 percent.

No standard classification of ice-cream has yet been adopted by the industry, even in developed countries. However, some of the important frozen desserts can be classified as follows.

II. Types

There are various types of ice-cream available in the market. The different types of ice-creams are based on colour, flavour, taste and the base composition. The different types of ice-creams consumed are briefly stated here.

1. PlainIt is an ice cream in which the colour and flavour ingredients together amount to less

than 5 percent of the volume of the unfrozen ice cream.

2. ChocolateIt is an ice cream flavoured with cocoa or chocolate.

3. FruitsIt is an ice cream containing fruits with or without additional fruit flavouring or colour.

Fruits such as strawberry, apricot, pineapple, mango, banana, frozen, packed, canned or preserved are added.

4. NutIce cream containing nut, such as almonds, pistachio walnuts, cashewnuts etc. with or

without additional flavouring or colour.

5. Milk ices or milk lolliesThese cream are frozen product obtained from milk, skim milk or milk products with or

without the addition of cane sugar, eggs, fruits, fruit juices, nuts chocolates, edible flavours and permitted food colours. The product should contain not more than 2.0% milk fat, not less than 3.5 percent proteins and not less than 20% total solids.

6. IceIce are made of fruits juice, sugar and stabilizer with or without additional fruit acid,

colour, flavouring or water, and frozen to the consistency of ice cream. Usually contain 28 to 29 percent sugar, 20 to 25 percent over run and no dairy products.

7. SherbetSherbet is made of fruit juices, sugar stabilizer, and milk products.

8. Fancy mouldedIn this, the ice-cream is moulded in fancy shapes and composed either of one colour and

flavour of ice cream or a combination of colours and flavours, or one decorated. Examples are: brick ice cream, cakes, cakes roll, moulds representing fruits etc.

9. NoveltiesA novelty ice-cream or frozen confectionary is an specially shaped and usually a low-

pieced package containing and individual serving whose main appeal consists in its shape, size, colour or convenience for eating.

10. Soft ice cream (softy)

Softy is sold as drawn from the freezer without hardening.

III. Ingredients and Composition

Commercial preparation of ice cream involves certain ingretients and constituents. These may be briefly mentioned and explained as follows:A. Dairy products

Dairy products include sweet cream, frozen cream, plastic cream, unsalted butter & butter oil. These also serve as a source of fat for the preparation of ice cream.Source of milk -not fat:-Skim milk-Skim milk powder-Condensed skim milk (plain I sweetened-Sweet cream butter milk.

B. Sweetening agents The sweetening agents used as additives for the r preparation of ice-cream

commercially are as following.-Corn sweetener: Refined com sugar (dextrose) or-Corn syrup (liquid) -Contain dextrose and maltose.-Dried corn syrup solids: Contain dextrose and maltose together with dextrin.-Invert sugar: Mixture of different parts of glucose and fructose and generally obtained in one from of syrup. Sweeter than sucrose.-Saccharin: This is most commonly used as an artificial sweetener.-Sucrose: This is commonly known as granulated cane or beet-sugar. This is the most widely accepted source of sugar thought the world.

C. Fruits and nutsThe various types of fruits and nuts used in ice-cream preparations are apple, banana,

mango, pineapple, grape almonds, pistachio, walnut, groundnut are generally used. They help to improve the acceptability and palatability of ice- cream.

D. AdditivesAdditives are the substances added in a food product in small amounts for a special

purpose. They are mainly chemical in nature. Additives are added in addition to other ingredients but for a special purpose.

1. ColoursThere are various forms of colouring agents used in the preparation of ice-cream. Mainly

the colours used are in, the powdered form or liquid form. The commonly used colours are yellow, green, pink, etc. depending on the type of ice- cream

2. Eggs solidsYolk solids improve whipping ability of the ice-cream mixture.

3. StabilizersThe various stabilizing agents used in the preparation of ice-cream are

-Gelatin of animal source-Sodium alginate -this is of vegetable origin and widely used,-Guargum -this is of Indian origin

4. EmulsifiersThe emulsifiers used in the preparation of ice-cream are the mono- or di-glycerides of fat

-forming fatty acids.

5. FlavoursThe flavouring agents used in the preparation of ice-cream are vanilla, chocolate,

strawberry, pineapple, lemon, banana, mango and orange etc.

E. EquipmentsThe following materials/equipments are required for the preparation of ice-cream:

-Mixing tank-Pasteurizing plant-Homogenizer-Ice-cream freezer-Filling unit-Hardening cabinet-Ice-cream cups with lids -Weighment facilities

F. Average compositionThe average composition of a plain ice-cream can be briefly enumrated here.

Total solids (percent by weight) -36.0 (minimum) Milk fat % -10.0 minAcidity % -0.25 (max) Sucrose % -15.00 (max)Weight in grams, per lit/min -525IV. Role of the constituents

The various ingredients and constituents used in the preparation of ice-cream have been discussed. Now, here we discuss about the role, function and importance of these constituents in the ice-cream.

1. Milk fatMilk fat helps to enrich and give a full, creamy flavour. If the milk fat is slightly off-

flavoured, the defect will be noticeable. The fat also contributes to the body and melting resistance of ice-cream while producing a smoothness of texture.

2. Milk -solids -not fat (MSNF)They consist of milk proteins, milk sugar and mineral matter, They are high in food value

and also inexpensive. The milk proteins help to make ice- cream more compact and smooth,

3. SugarThe main function of sugar is to increase the acceptability of ice-cream. The desired

sweetening effect is only produced by sucrose, Sugar are usually the cheapest source of the total solids in the mix.

4. StabilizersStabilizers are used to prevent the formation of objectionably large ice crystals in ice-

cream, especially during storage since they are added in very small quantities, they have a negligible influence on food value and flavour.

5. EmulsifiersEmulsifiers are used mainly to improve and provide a uniform whipping quality to the

mixture, and to produce a drier ice-cream with smoother body and texture.

6. Flavour and colourFlavour increases the acceptability of ice-cream, and colour improves its aesthetic

appeal.

V. Manufacturing Methods

A simple process for the manufacture of ice- cream is given below.

1. Procurement of raw materialMilk and cream or any other raw milk products should be fresh and free from any kind of

off-flavour. Other material such as sugar, stabilizer and colour should also be pure and of high quality.

2. Cleaning and sterilization of appliancesAssemble the freezer part and the utensils to be used. Thoroughly clean them using

about 25% soda solution. Sterilize with hot water above 180°F. This should be done in order to ensure freedom from off -flavours to reduce bacterial count, and to avoid contamination of pathogenic organisms.

3.1ce-cream mix preparationFirst of all, weigh separately all the ingredients to be used. Then mix the ingredients

thoroughly with sugar while heating and this mixture slowly to the liquid ingredients. The order in which ingredients are added as follows.

All liquid ingredients are placed in the jacketed vat provided with a power stirrer. The dry ingredients including skim milk powder, sugar and stabilizer, are added while the liquid material is agitated and before the temperature reaches 49°c (120°F). Proper suspension to avoid lumpiness of the dry ingredients may be obtained by either mixing the dry material thoroghly with part of the sugar before slowly adding it to the liquid or by slowly adding these substance to the liquid.

If gelatin is the stabilizer used, it is best added after it is thoroughly mixed with an equal volume of sugar, and before the liquid material reaches 49°C (120°F) alternative, it can be sprinkled on the surface of the cold liquid and allowed to soak before the mixture is heated, or soaked in water and then the mixture is heated to completely dissolve the gelatin, which is usually added to a warm (38- 49°/100°- 120° F) mix.

If sodium alginate is used, it should not be added until the temperature of the liquid material has reached at least 66° (150°F). The dry sodium alginate is not allowed to soak but is stirred up with cold water and immediately dumped into the hot mix.

When butter, plastic cream, frozen cream or other frozen products are used, they should be cut into fairly small pieces and added after time has been given to allow for complete melting before the pasteurizing temperature is reached.

4. Pasteurizing

Proper pasturization of all ice -cream mixes is compulsory because this process destroys all pathogenic or disease producing bacteria, thereby safe guarding the health of the consumer.

The advantages of pasturization are

a. It renders the mix completely free of pathogenic bacteriab. Dissolves and help to the blend the ingridient of the mixc. It improves flavourd. It improves keeping qualitye. It produces a mole uniform product.

Proper pasteurization consist in rapidly heating the mix to a definite temperature (68.5oC or 155° F) holding it at that temperature for a definite minimum period of time (30 minutes) and then rapidly cooling it below 5°C (40° F).

5. HomogenizationHomogenization of the ice-cream mix is essential. The main purpose of homogenization

is to make a permanent and uniform suspension of fat by reducing the size of the fat globule to a very small diameter. It provides a more uniform and smoother texture to the ice-cream.

The mix is usually homogenized at temperature from 63° to 77° C (145 ° to 170°F). For the house hold preparation the mixie can be used for the homogenization process.

6. Cooling and ageingCooling the mix immediately after homogenization to 0- 5°C (32-40°F) is essential after

which it should be held in ageing tanks until used. Ageing refers to holding the mix at a low temperature for a definite time before freezing. The ageing temperature should not exceed 5°C (40°F). The ageing time under average commercial condition may be 3 to 4 hours. Ageing improves the body and texture of ice-cream and increase melting resistance.

7. Freezing the mixWhen the mix has been properly aged. it is ready for the freezing process, which follows

immediately. Freezing is one of the most important operation in the making of ice-cream on which depends the quality, palatability and yield of the finished product.

When the ice-cream is partially frozen to a certain consistency, it is drawn from the freezer into packages and quickly transferred to cold storage rooms, where the freezing and hardening process is completed.

Normally the freezing will take place in about 10 minutes. Freezing may be stopped when the ice-cream has progressed to a sufficient stiffness.

8. Hardening and storageWhen ice-cream is drawn from the freezer and put into the container to be placed in the

hardening room, it has a semi -fluid consistency not stiff enough to hold it in shape. The freeing process is, therefore continued without agitation during hardening until the temperature of the ice-cream reaches -18 ° C (O°F) below. Most operators allows a hardening time for 12 hours. As in the freezer, quickly hardening is better, since slow hardening gives rise to large ice crystals and coarseness. The different hardening systems are given in the following table 1.

Table 1: Ice-cream hardening systems

Sl.No Hardening systems Temp. maintainedC F

1 Hardening rooms (-) 12 to (-) 45 10 to (-) 502 Hardening tunnels (-) 34 to (-) 45 (-) 30 to (-) 503 Hardening cabinets (-) 23 to (-) 26 (-) 10 to (-) 15

After the ice -cream is hardened, it may be immediately marketed, or it may be stored for a week or two at the most.

The operation of storage rooms is the same as for the hardening room with two exceptions: The temperature should be maintained uni-formily at a point between -23o C to -18 °C (-10oF to 0oF) and the packages should be piled very close to each other.Some precaution to be observed in the operation of hardening or storage rooms are:

a. Provide facilities for calling for aid, if the operator accidentally is trapped inside.b. Keep both an axe and a sledge hammer in a definite place just inside the door.c. Avoid fluctuation in the temperature.

9. OverrunOverrun is usually defined as the volume of ice-cream obtained in excess of the volume

of mix. It is usually expressed as a percentage. This increased volume is composed mainly of the air incorporated during the freezing process. The amount of air which is incorporated depends upon the composition of the mix and the way it is processed and is regulated so as to give that percentage of overrun or yield which will give the proper body, texture and palatability necessary to a good quality products. Too much air will produce a snowy, fluffy, unpalatable ice-cream while too little, a soggy and heavy product. The desirable percentage overrun in different ice- creams is given in the following table 2.

Table 2: Percentage overnln in ice-creamsSl.No Products % overrun1 Ice-cream packaged 70 to 802 Ice-cream bulk 90 to 1003 Soft ice-cream (softy) 30 to 50

10. DistributionWhen ice-cream is marketed, the manufacturer usually transports it to the retailer under

refrigeration at the same temperature as is maintained in the retailer cabinet. The various methods of refrigerating the distribution vehicle are:

a. Dry ice refrigerationThe dry ice is solid carbon dioxide with a freezing point of –78o C ( -109o F). It is used

extensively for packages delivers. I It is cut into pieces of an appropriate size, which are wrapped in paper to delay the rapid evaporation, and then placed around the package of the ice-cream inside an insulated packet or in a single service type packet. The later is usually a cardboard box and is used especially for the carry package. This system is popular for the carry out package. This system is popular for retailing ice-cream in push cart in big cities of India.

AdvantagesThe advantages of dry ice refrigeration system can be briefly mentioned here.

-It is neither moist nor messy.-The package is neat in appearance. -It is very light.

ii. DisadvantagesThe disadvantages of the dry ice refrigeration system can be briefly enumerated here.

-At present, it is expensive and availability is limited.-Loss during handling and storage is up to 10 -15%-There greater opportunity for heat shock, which may injure texture of the ice-cream.

b. Refrigerated truckThis is the most commonly used means of the transportation for ice-cream in developed

countries. The truck is refrigerated overnight, and loaded with hardened ice cream the following morning.

c. Frozen containers (Freezers)Jacketed metal containers, known as Eutectic pads, which contain calcium chloride.

Solution of specific gravity of amount 1.1, are refrigerated in a similar brine tank whose specific gravity is about 1.26, at a temperature of -32° C (-25°F) The container attain a temperature of -21°C (-5°F) and are then placed around the packaged ice-cream. This arrangement is used by a few ice-cream factories for air-lifting ice-cream in this country .

A. Soft Ice-cream (softy)There is a tremendous demand for the form of ice -cream which has generally come to

be known as "softy". The term has been applied largely because this product is marketed in a soft condition and is ready for consumption shortly after it is drawn from the freezer.

It is solid under different trade names such as Dairy Queen, Zesto, Sweeden freeze. But in our country it is mostly known as "SOFfY".

The composition of the softy ice-cream has been given in the following table 3.

Table 3: Composition of soft Ice-cream

Sl.No Constituent Percentage1 Fat -3 to 62 Milk-solid (not fat) -11 to 143 Sugar -12 to 154 Stabilizer & emulsifier -0.4 to 0.6

1. Selection of ingredients for preparation of softyThe following essential and optional ingredients are required for the preparation of softy

commercially.

a. Dairy productsEssential Ingredients Optional Ingredients

1. Fresh sweet milk 1. Plain condensed milk2. Fresh sweet cream 2. Plain condensed skim milk3. Dried skim milk 3. Sweetened condensed milk

4. Sweetened condensed skim milk5. Evaporated milk6. Sweet butter milk poV(der7. Cream8. Sweet, unsalted butter9. Butter oil

b. Sweetening AgentsEssential Optional1. Cane sugar 1. Dextrose, gulcose or com sugar

2. Com syrup, liquid or driedc. Stabilizers and ErnulsifersEssential Optional1. Sodium alginate 1. Indian gum (Stabilizer)2. Glycerol mono-stearate 2. Agar-agar(G.M.S.)(Emulsifier) 3. Pactin

4. Sodium-coboxy-methyl alluloso (CMC)

d. FlavouringNatural Artificial1. Vanilla 1. Vanilla compounds2. OJcoa 2. Artificial fruit flavours3. Chocolate etc. 3. Imitation not flavour etc.4. Strawberry5. Pineapple6. Lemon 7. Banana 8. Mango 9. Orange

e. ColoursIt is very essential that the colour of soft serve ice-cream must match with the

corresponding flavour used.

2. Mixing the ingredientsTo avoid difficulties in mixing precalculated quantities of milk powder, sugar and

stabilizer emulsifier should be mixed in the lot. Similarly the liquid ingredients, namely cream and milk should be mixed separately in a container. The solids should be mixed with the liquid ingredient gradually with constant stirring and heating to the temperature of 150°F (65.5°C).

3. HomogenizationIn order to avoid fat separation and fat churning in soft ice-crearn, the mix should be

homogenized resulting in breaking of fat globules. All the mixes should be heated to 1.50°F (65.5°C) and homogenized in 2 stages, first at a pressure of 2500 psi. and then at 500 psi. For the household preparation mixie can be used for homogenization.

4. PasteurizationTo safeguard the health of consumers by way of destroying all pathogenic and disease

producing organisms present in soft ice-cream mix it must always be pasteurized.

For small quantities of mix, pasteurization can be carried out in cans dipped in hot water heated by steam. All the mixes must be pasteurized at 160°F (71.7°C) for 30 minutes.

5. Cooling The mixes could be initially be cooled by dipping the cans in tap water. The mixes can

further be cooled to about 20°C (68°F) by immersing the cans in chilled water.

6. FreezingA softy ice cream freezer, apart from freezing a portion of water of ice-cream mix, also

incorporates the air in the mix to obtain a swell in volume or overrun. To get efficient freezing and good overrun in the ice-cream it is very essential that the optimum quantity of the mix should be taken in the freezer for freezing.

This quantity of mix varies from freezer to freezer. So the freezer manufacturers advice should be followed strictly when taking the quantity of mix for freezing. Once the ice cream has dry appearance, good in consistency, contains 50- 60 percent overrun and has a temperature of -9.6°C (22.5°F), it should be drawn and served to the consumers.

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