Ice cream-Definition,Nutritive value,Classification and its properties

ICE CREAM

  • Ice cream may be defined as a frozen dairy product made by suitable blending and processing of cream and other dairy products togetherwith sugar and flavour, with or without stabilizers or colour, and with the incorporation of air during the freezing process.
  • According to the PFA rules (1976) ice cream is the frozenproduct obtained from the cow or buffalomilk or a combination thereof or from cream and or on the milk products, withor without the addition of cane sugar,eggs, fruits, fruit juices , preserved fruits, nuts, chocolate, edible flavours and permitted colours. It may contain permitted stabilizers and emulsifiers not exceeding 0.5 per cent by weight. The mixture must be suitably heated before freezing. The product should contain not less than 10%milk fat, 3.5% protein, and 36% total solids. However, when any of the aforesaid preparations contains fruits or nuts or both, the content of milk fat may be proportionately reduced but not less than 8 % by weight, starch may beadded to a maximum extent of 5 %, with a declaration to that effect on thelabel.

Classification

Some of the frozen deserts can be classified as follows.

  • Plain: Ice cream in which the colour and flavouring ingredients together amounts to less than 5 per cent of the volume of the unfrozen ice cream. Example: vanilla and coffee ice creams.
  • Chocolate: Ice cream flavoured with cocoa or chocolate.
  • Fruit: Ice cream containing fruits with or without additional fruit flavouring or colour. Fruits such as strawberry, apricot, pineapple, mango, banana, etc., may be fresh, frozen, frozen packed, canned or preserved.
  • Nut: Icecream containing nuts, such as almonds, pistachio, walnuts, cashew nut, etc.,with or without additional flavoring or color.
  • Milk ices or lollies: According to the PFA rules (1976) theserefers to the frozen product obtained from the milk or skim milk or milkproducts with or without the addition ofcane sugar, eggs, fruits, nuts, chocolate, edible flavours, and permitted foodcolours. It may contain permitted stabilizers not exceeding 0.5 % of the product. The mixture should be suitably heat treated before freezing. The product should contain not more than 2.0% milk fat, less than 3.5% proteins andnot less than 20.0% total solids.
  • Ices: Made of fruit juices sugar and stabilizers with or without additional fruit acid, colour, flavouring, or water, and frozen to the consistency of ice cream. Usually contain 28 to 30 per cent sugar, 20 – 25per cent over run and no dairy products.
  • Sherbet: made of juices, sugar, stabilizers and milkproducts. It is similar to an ice except that milk, either whole, skim,condensed or powdered, or ice cream mix, are used in place of all or, part of the water in an ice.
  • Fancy moulded: Moulded in fancy shapes and composed eitherof one colour and flavour of ice cream or a combination of colours and flavours, or especially decorated. Examples:are brick ice cream, cakes, cake roll, moulds representing fruits, etc.
  • Novelties: Novelty ice cream or frozen is an especiallyshaped and usually low priced package containing an individual serving whosemain appeal consists in its shape, size, colour or convenience for eating.
  • Soft ice cream: Sold as drawn from the freezer without hardening.

Composition

  • The composition of ice cream is usually expressed as apercentage of its constituents, i.e. a percentage of milk fat, milk solids notfat, sugar, stabilizers, total solids etc. Its composition varies in different localities and in different markets.

The ISI specifications foe ice cream are given below

S.NO.

Characteristics

Requirements

1.

weight (g./litre/min.

525

2

Total solids(%wt .min)

36.0

3.

Milk fat (% wt. Min.)

10.0 (Tentative)

4.

Acidity (% lactic acid max.)

0.25

5.

Sucrose (%wt. Max.)

15.0

6.

stabilizers/emulsifiers(%wt. Max)

0.5

7.

Standard plate counts (per g.)

Not more than 2,50,000

8.

Coliform count (per g.)

Not more than 90

9.

phosphatase test.

Negative.

Food and nutritive value

  • Ice cream contains two to three times as much fat and slightly more protein than does milk. In addition it may contain other food products such as fruits, nuts, eggs, and sugar which enhance its food value. However, likemilk, it lacks iron, vitamin C, and some of the trace minerals.
  • Ice cream is a rich source of calcium, phosphorus and other minerals of vital importance in building good bones and teeth.
  • Being rich in lactose, ice cream favours greater assimilation of the calcium content on the diet.
  • The protein content of ice cream rates high both in quantity and quality. The milk and egg proteins are complete, that is, they contain all the amino acids essential to animal life and are especially important sources of tryptophan and lysine which are lacking in many plant proteins. Ice cream provides these valuable proteins in a very palatable form. In fact, ice creamis the most palatable source of milk proteins to vegetarians.
  • Ice cream is an excellent source of food energy. Having twice to three times the fat content ofmilk. And more than half of its total solids being sugar the energy value of ice cream is very high. It is therefore, a very desirable food itemfor growing children and persons who need to put on weight.
  • Ice cream, is a rich source of essential vitamins, without which normal health and growth cannot be maintained. Thus it is an excellent source of vitamin A, a good source of vitamin Band G (riboflavin) and a fairly good source of Niacin, vitamin E, and in fruitice cream, of vitamin C. The digestibility and palatability of ice cream is also very high.

Role of the constituents in ice cream

  • Milk fat:this is high in food value, but expensive. It enriches and mellows the ice cream, giving it a full, rich, creamy flavour. If the milk fat is even 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. Fat gives stability to the ice cream but impairs whipping ability.
  • Milk solidsnot fat: they add very little to the smell, but improve its body and texture,however milk sugar adds to the sweet taste. The milk proteins help to make ice cream more compact and smooth. Milk SNF should be added in as large a quantity as possible without risking the danger of sandiness. They are high in food value and also inexpensive.
  • Sugar: the main function of sugar is to increase the acceptability of ice cream. The desired sweetening effect is only produced by sucrose. Sugars are usuallythe cheapest source of total solids in the mix.
  • Stabilizers: these are used to prevent the formation ofobjectionable 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 flavor.
  • Emulsifiers: These are used mainly to improve upon andprovide a uniform whipping quality of the mixture, and to produce a drier icecream with smoother body and texture.
  • Flavor andcolours: flavor increases the acceptability of ice cream, and colours its aesthetic appeal.

Properties of mix

The properties of practical importance on the mix are

  • Viscosity: This is defined as the resistance offered by liquids to flow. Viscosity is considered an important property of the ice cream mix, and a certain amount of it seems essential for proper whipping and the retention of air. Two types of viscosity exists in ice cream mixes:
  • Apparent viscosity: This is a thickened condition that disappear with agitation, and Basic viscosity: which remains after the apparent viscosity disappears. The viscosity of ice cream mix is influenced by composition, kind and quality of ingredients, processing and handling of the mix , total solids concentration and temperature.

Acidity and pH

The normal acidity of ice cream mixes is dependent upon the serum solids content, and is calculated by the formula:

(% serumsolids in mix / % serumsolids in milk) X  % Acidity of mix = % Acidity of milk

The normalacidity of ice cream mix is 0.15%. The pH of ice cream mix should be 6.3. If the mix acidity is more, it maybe neutralized with suitable neutralizers Eg. Sodium bicarbonate. It should be remembered that good ice cream couldn't be made from a highly acidic cream.

Mixstability

  • This refers to stability or resistance toseparation by the milk proteins in an ice cream mix. Instability results in separation of milk proteins as coagulated or precipitated material in the mix, and the resulting ice cream has a curdled appearance on melting. Mix stability is affected by high mix acidity, low citrate and phosphate content, high calcium and magnesiumcontinent, high homogenizing pressure, high heat treatment, low ageing time,destabilizing effect of freezing etc.

Surface tension

  • This refers to the force of attraction between the moleculesof a liquid at its surface. The greater the attraction between the molecules,the higher the surface tension and vice versa. The unit of measurement of surface tension isdyne.
  • The surface tension can be readily decreased by the additionof emulsifiers. Mixes with lower surfacetension values will have excessive whipping rate , fluffy short bodycharacteristics and susceptibility to the shrinkage defect. the normal surface tension value of ice cream mix may range from 48- 53dynes/sq.cm.

Freezing point

  • The freezing point of ice cream is dependent on the soluble constituents and varies with its composition. The mix constituents, which affect the freezing point directly,are sugar, milk sugar, milk salts, and any other substances that may have been added and are in true solution. Freezing point is indirectly affected by fat,protein and any other constituents not in true solution by replacing water. Glucose, sucrose and corn sugar depress the freezing point in the descending order. In fruit ice-cream the freezing point will depend on the type of sugar used in fruit preparations.
  • An average mix has a freezing point of 27.5ºF. mixes with high sugar and milk solidsnot fat content s may range to 26.5ºF, while high fat ,low MSNF or low sugarcontent mixes may range to 29.5ºF.

Whipping rate

  • A high whipping rate means the ability to whip rapidly to ahigh over run. The present hypothesis isthat whipping ability is based on the tensile strength and the strength of the lamella (i.e. walls around the air cells). Whipping ability is improved by a high processing temperature, proper homogenization and ageing the mix for 2-4hours.
  • Smaller fat globules and less clumping of fat globulesincrease the whipping ability. Mixes made from butter, butter oil, or frozen cream have poor whipping ability . Eggyolk solids , fresh cream, buttermilk solids improve whipping ability. Sugar decrease the whipping ability except when added after homogenization , in which case it increases it.
  • The construction and operation of freezer affect thewhipping ability.
  • The rate of whipping is measured by calculation the over run at one minute intervals while the mix is being frozen in a batch freezer,normally within 3 to 5 minutes after the freezing process starts, the mix is frozen and within 7 minutes an overrun of 90 percent is obtained. In mixes, which have a rapid whipping rate,90 per cent overrun may be reached in 5 minutes or less. Mixes requiring 8 minutes of more to reach 90 per cent overrun are considered to have slow whipping rate.
Last modified: Monday, 16 April 2012, 10:24 AM