CARACTERISTICAS GEOGRAFICAS

The important constituents of spreads are milk fat, milk proteins, emulsifiers, stabilizers, emulsifying salts, acidiluants, common salts, colouring and flavouring materials, vitamins, preservatives, antioxidants, etc. Each ingredients has specific importance in production of good quality spread.

7.1.1 Function of fat

Fat provides structure, energy and taste including creaminess. It act as carrier of flavour and vitamins and also source of essential fatty acids. The physical properties of spreads, namely spreadability, firmness, plasticity and thixotropy are mainly determined by the ratio of liquid to solid fat content. Fat are usually selected from milk fat and its fractions or vegetable fats/oils or combination of both. Milk fat include cream, butter and butter oil.

On the basis of flavour and composition corn, safflower, sunflower, soybean and groundnut oils have been preferred for spread.

7.1.2 Function of proteins

Milk proteins are added to the spread for their organoleptic functional and nutritional properties. They imparts creamy taste, thereby improving consumer acceptability. They contribute viscosity and water holding capacity to the aqueous phase, thereby improving emulsion stability during processing and storage. Milk proteins supply the essential amino acids and improve the nutritional value of the product. The main source of milk proteins are skim milk, butter milk, caseinates, whey solidsin the form of concentrated or dried or retentate form. Use of cheese in spread would not only provide protein but also help in imparting cheese flavour to the product (Shiller et al., 1977 and Sprenger, 1981). Soy protein isolate, vegetable proteins, can be used in manufacture of spread because of high water holding capacity (Kinsella,1978), high protein quality (Gupta and Kapoor, 1978). It can be also used in the form of protein-lipid concentrate so as to utilize the polyunsaturated soys oil as well.

7.1.3 Emulsifiers

In combination with milk proteins (when used) emulsifiers are generally of the fat soluble type and primarily help to reduce the size of aqueous droplets and contribute a dairy like taste to the product. Mostly they function by creating stabilizing films at the water/oil interface and by altering the other characteristics such as the wettability by water of the fat crystals. They have ability to yield the softer and more easily spreadable product with stable emulsion. Various emulsifiers used in spread are monoglycerides (MG) of saturated and unsaturated fatty acids, egg yolk solids, lecithin, combination of lecithin and MG, etc. The proportion of emulsifier in spread varies from 0.1 to 0,6%.

7.1.4 Emulsifying salts

In addition to assisting the emulsification process, emulsifying salts also improve the texture of the spreads. These salts are believed to modify the emulsification of fat. They are known to contribute to the texture of products like spreads especially of O/W type. The

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common emulsifying salts used are tri sodium citrate, di-sodium phosphate and their combination, etc. and are added at he rate of 1to 4%.

7.1.5 Stabilizers

Stabilizers are especially important in reduced/low fat spreads and help to promote water in W/O by inhibiting coalescence of aqueous phase droplets during product processing and in use situations, and by balancing the viscosity of the two phases which make up the spread, namely water and fat. High water holding ability of stabilizers play an important role in improving body and texture of spreads. Various stabilizers like gelatin, carboxyl methyl cellulose, starch, modified starch, sodium alginates, carrageenan, etc. can be used alone or in combination at the rate of 0.1 to 0.5 %.

7.1.6 Plasticizer

Plasticizers like glycerol, sorbitol, glycol, etc. may be used in spreadable products to impart pliability or plasticity to them. They have an ability to depress the water activity of the aqueous phase (Holscher and Dijkshoorn, 1980). This may help in extending the shelf life of the product. Addition of glycerol and sorbitol at the rate of 0.5 to 1.0 % in soy based low fat spread, improve the mouth feel without any adverse effect on firmness of the spread (Patel and Gupta, 1988). According to Seas and Spurgeon (1975), use of 2 to 4 % sorbitol in cheese flavoured dairy spread could partially limit lactose crystallization.

7.1.7 Acidifying agent:

Spreads, particularly low fat types, have low storage stability because of their high moisture content. A low pH in the food system retards bacterial growth and thus helps in extending the shelf life. Best body and least ‘weeping’ have been obtained with pH 5.7- 5.9 (Spurgeon et al., 1973). Lactic, acetic, citric acid, glucono- delta- lactone etc. can be use as acidifying agent.

7.1.8 Common salts

Sodium chloride or table salts usually added in spreads, which not only provides taste and palatability to the spread but also retards the growth of bacteria and thereby acting as preservative. Generally the salt content in spreads varies from 0.25 to 2%.

7.1.9 Colouring materials

In order to simulate the colour of the spreads, the colouring matters used are annatto and beeta carotene. Use of beeta carotene enhances not only the nutritive value but also the oxidative stability t the product.

7.1.10 Flavouring material

Dairy spreads are blend of different ingredient, dairy or non-dairy, it may or may not have the desired flavour. It is thus essential that external flavouring are added to evelop or impart desired flavour. Butter starters, butter culture flavour concentrate, starter distillate, synthetic butter flavour etc. used successfully for butter flavoured spreads. Diacetyl, lactones, phenols, delta-lactone etc. can be used in such spreads.

Cheese flavoured spreads involve the use of cheese flavour concentrate, aged Cheddar cheese, smoked aged Cheddar and blue cheese. Shiller et al., (1977) added melted cheese as a protein ingredient and obtained a low fat spread with a flavour of matured ripe cheese and high overall quality.

According to Lang and Lang (1970), other flavours used which include ham, herbs, shallots, garlic cocolate, vanilla, honey, nuts, etc.

7.1.11 Preservatives

To inhibit the growth of spoilage organisms and yeast and mold , in addition to heat treatment, addition of various preservatives is required. The various preservatives used include sorbic acid, salts of sodium, potassium and calcium , nisin, propionates, sodium benzoate etc. and can be added at the rate of 0.03 to 0.1%.

Other additives like anti-oxidants, vitamins, sweeteners, etc. can be incorporated to spreads.

7.2 Processing

The formulation and processing of spreads generally determine the final product quality such as appearance, taste, spreadability and keeping quality. The processing of spreads making involve preparation of aqueous and fat phase and their mixing, heat treatments, emulsification, cooling/crystallization, working, filling, packaging and setting.

7.2.1 Preparation of Phases

Aqueous phase preparation involves of dissolving of water soluble dairy and non dairy ingredients namely protein, stabilizer, salt, etc., Blending temperature between 40 to 80°C is generally used for faster dispersion and solubilization of ingredients. Flavouring ingredients should be incorporated at the end of heating to minimize the loss of volatile flavour. Pasteurization, homogenization and cooling are given before addition/blending into fat phase.

Desired flavour and melting characteristic is very important in spread making and is influenced by the fat phase preparation. Blending involves melting of fat, mixing it with other fat soluble vitamins and colouring ingredients.

Spreads preparation also involve mixing of all required ingredients together rather than preparation of two phases separately. The temperature used for mixing varies from 15 to 65°C.

7.2.1 Heat treatment

It is suggested to pasteurize the aqueous and fat phase before emulsion formation to minimize microbial contamination and to make the product safe for human consumption. The time temperature combinations used are 75°C for 30 min., 85°C for 5 min. and 95°C without holding.

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7.2.2 Cooling of fat phase

It is commonly known to prepare fat compositions by cooling liquid fat or aqueous emulsion of fat, very often during cooling the desired crystal structure is not obtained and, therefore, taste, spreadability and other physical properties are impaired. In order to obtain outstanding properties of the final product a very specific crystal structure is required. This can be achieved by rapid cooling of the fat phase (Prajapati et al., 1991 and Verma, 1996).

7.2.3 Emulsification

Emulsification is an important process to get stable product during handling and storage. Emulsification process can be carried out by blending, homogenization, shearing action, churning, heat shock cooling etc. Blending of two phases can be carried out using Hobart Food Mixer, high shear mixer, etc. Various other methods have been suggested, namely Stephan thermizing unit, kneading action, plasticizing by cutting action with sharp blades, SRS vacuum cooler and colloidal mill methods.

7.2.4 Working

The process of working ideally disperse the fat crystals throughout the emulsion and if the process is carried out satisfactorily, the product will be plastic and spreadable; if not it will be greasy. Degree of working by scraped surface cooling affects the characteristics of low fat spread. Preparation of high moisture spreads of W/O type emulsion requires more intensive working at high refrigeration temperature than margarine. Maximum working at low temperature produces the hardest product. By churning method, butter with additional water requires working to manufacture low fat butter.

7.2.5 Packing

Water and air proofs Containers are required for packaging of spread. Various kind of packaging materials namely ice-cream cups, plastic coated cartoons, semi-plastic containers, plastic coated paper packs, polyethylene lined paperboard containers, parchment paper, colorued glass containers and polystyrene cups are used.

7.2.6 Setting

Setting is the phenomenon where the spread is usually kept at low temperature for several hours to get desired degree of consistency. Crystallization of fat during setting helps in attainment of final body characteristics. Setting temperatures govern the rheological properties of the product by influencing the number of crystal particles. Number of crystal particles vary even with slight changes in temperature. Higher temperature of setting yields a butter with lower hardness in comparison those set at lower with temperature. Setting temperature and duration varies from 0 to 15 C for 4 hours to 48 hours, respectively.