Butter

Butter is the smooth, fatty substance obtained from churning cream with fat content of at least 35 per cent. Simple agitation of this cream in machines known as churns ruptures the membranes of fat globules and these globules then group into granules of butter. Because only the milkfat is used, ten litres of whole milk are required to produce 500 g of butter. The majority of butter made in Canada is salted after churning, using sodium chloride during the creaming process. The salt performs two main functions: enhances the taste and prolongs the preservation of the product by inhibiting the growth of microorganisms.

The packaging used for butter further protects it against light, oxidization, odour absorption, evaporation and discolouration. Good quality butter which is then frozen at minus 17.C following its manufacture can be stored in excess of one year at that temperature. However, once opened, butter must normally be used within three weeks. For the sake of consistency and appearance, butter should be refrigerated at a temperature of 5.C.

Prepared in accordance with strict manufacturing practices, butter is produced from milk or milk products, and contains no less than 80 per cent milk fat. Commercial butter contains 80 to 82 per cent fat, which is of animal origin, 14 to 16 per cent moisture and 0 to 4 per cent salt. The butterfat is composed of 62 per cent saturated fatty acids and contains lecithin (0.25 per cent) and cholesterol (2.2 mg/g of butter).

Butter is an excellent source of vitamin A since it contains more than 30 IU per g and is generally considered to be safe from pathogens. The latter fact is attributed to the low water content of butter, which is a water-in-oil emulsion that contains numerous microscopic droplets of water that are relatively high in sodium chloride concentration. The fat portion of butter is generally safe from microbial degradation.

Features and appearance: The quality of butter is based on its body, texture, flavour and appearance. It owes its characteristic and individual flavour to its own particular saturated fatty acid known as butyric acid. The colour and flavour may vary according to the type of cattle, season of the year, method of manufacture and amount of salt added. The colour of butter further varies with the content of carotenoids, which make up 11 to 50 per cent of the total vitamin A activity of milk. As the carotenoid content of milk normally fluctuates between winter and summer, butter produced in winter has a brighter colour. Carotene is added to ensure a uniform colour and consistent vitamin A content.

Butter should also be dense and taste fresh. The moisture content should be dispersed in fine droplets so that the butter looks dry. The consistency should be smooth, so that the butter is easy to spread and melts readily in the mouth. Butter provides 7.2 calories/g.

Butter plays a prominent role in the cooking of many countries, as it gives an unequaled taste to food and its ability to absorb helps to concentrate flavours. It is used particularly in sauces (Béarnaise, Hollandaise, kneaded butter, red), pastries (butter cream, puff pastry), creams and potages. It is a basic ingredient in breads, canapés and sandwiches.

In baking and grilling, butter must not be heated at a high temperature - it burns at a lower heat than oil or margarine, and its fat decomposes between 120 and 130.C. Butter heated at a high heat will have an indigestible and unappealing brownish colour. However, when combined with oil, butter will decompose less rapidly (heat the oil before adding the butter). Butter is more easily digestible fresh than melted, as it is still in its emulsified form.

In addition to imparting an "upscale/gourmet" image, butter performs a variety of functions in baked products (cakes, pastries, laminated doughs, breads and biscuits). It contributes to flavour, mouthfeel, texture and shelf life.

• Flavour: Butter's pleasant flavour is made up of many volatiles and nonvolatile compounds. It gives a distinctive flavour to all kinds of prepared foods. It also absorbs natural flavours and consequently, helps in the uniform distribution of flavourings. Reaction flavour compounds (lactones) are generated from the fatty acids of butterfat during baking. Lecithin is instrumental in stabilizing fat emulsions, leading to the uniformity of texture, aroma and flavour in baked foods.
• Mouthfeel: Butter provides highly desirable mouthfeel characteristics to baked products. Mouthfeel is related to the ratio of the crystalline (solid) and noncrystalline (liquid) fractions of butter as a function of temperature. It melts completely at37.8.C and, when introduced to the mouth, only five per cent is in solid form, and therefore it does not have a "waxy" mouthfeel.
• Texture: Butter serves a useful function in creating flakiness in laminated dough like croissants, Danish and puff pastries. Flakiness is caused by trapped carbon dioxide. When the pastry is baked, moisture in the butter turns into steam. Carbon dioxide is released from the leavening, making the dough layers rise. The rise (or volume) of baked pastry is directly proportional to the percentage of solid fat. For pies and tarts, flakiness is increased by mixing part of the butter into the dough. Cold butter works well. In the production of cookies, cakes, breads, and icings, butter is warmed to room temperature. For cake batters, sugar is thoroughly mixed with butter at room temperature to achieve a uniform distribution in the batter or dough. Butter contributes tenderness to bread by interfering with the development of the gluten network.
• Other benefits: Milk fat from butter acts as abarrier to preventing loss of moisture in finished baked goods. It gives an attractive appearance to bread when spread on the loaf surface. Furthermore, it is claimed to slow retrogradation of starch (which is associated with staling). Thus, tenderness and flakiness are maintained during the shelf life of baked goods. This effect on shelf life is observed in cakes as well as in yeast or chemically leavened breads.

For more information on butter, please visit the University of Guelph's Dairy Science and Technology Web site.