Dairy Products

I J Buttriss, British Nutrition Foundation, London, UK © 2005 Elsevier Ltd. All rights reserved.

Introduction

Dairy products are traditional dietary items in many parts of the world, in particular regions such as northern Europe where the cooler climate is especially suited to dairying. The history of milk as a food has been documented over the centuries and examples of early dairying are depicted in Egyptian friezes such as that from the sarcophagus of Queen Kawit from Der-al-Bahri, between Luxor and Karnak, dating back 4000 years. There is an even earlier Mesopotamian frieze from the temple of Ninkhasarg, near Ur, which is thought to be 1000 years older.

The popularity of milk as a staple food over the centuries must partly be due to its versatility. Early humans discovered that milk could be churned to make butter and fermented with bacterial cultures to produce cheese and yogurt, all of which were methods of preserving some or all of the nutrients in milk for consumption at a later date.

Variety

The range of dairy products on the market is immense. In most countries, a range of milks with differing fat contents is available. For example, in the UK consumers can choose between Channel Islands milk, with 4.9 g per 100 g fat, whole milk (3.9 g per 100 g), semiskimmed (1.6 g per 100 g fat), and skimmed milk, which has virtually no fat. Similarly, a wide range of cheeses exists with varying fat contents: at one end of the spectrum are soft fresh cheeses, made with skimmed milk, and at the other, hard cheeses such as Cheddar. Also available is cheese made with nonanimal rennet, suitable for vegetarians. In the UK alone, about two hundred different cheeses are produced, and cheese is particularly popular in countries such as France, where an even greater variety is available.

Fermented milk products such as yogurt, smetana, and kefir have always been popular in Middle Eastern countries, but their popularity, particularly that of yogurt, is increasing dramatically in Europe. Again, a wide range of yogurts exists, from very low-fat varieties to the creamier, whole milk or Greek-style product. Today, the range includes set yogurts, stirred yogurts, fruit yogurts, frozen yogurts, drinking yogurts, fromage frais, and the newer 'bio' yogurts with their milder flavor.

Traditional products such as cream and butter are still in demand, in spite of their high fat content, and are being joined by other 'luxury' products such as real dairy ice creams, fresh cream desserts, and luxury mousses. To meet the demand for a spread with a buttery flavor, products have been developed which incorporate butterfat for taste but often have a lower fat and energy content than butter.

A number of products also exist to which nutrients have been added, such as calcium-enriched milks and yogurts fortified with additional vitamins.

Nutrient Composition of Milk and its Products

Milk can be described as one of the most nutritionally complete foods. It provides a wide range of essential nutrients, in particular protein, and a range of vitamins and minerals (Table 1). It is, however, a poor source of iron and vitamin D, and contains no starch or dietary fiber. By volume, water is the major constituent of milk, comprising just over 87%. The remainder consists of milk fat and solids-not-fat (SNF)-principally comprising protein, lactose and minerals.

Protein

The principal proteins found in milk and its products are casein, lactalbumin, and lactoglobulin. Milk protein has a high biological value since it contains all of the eight essential amino acids, which cannot be synthesized in the body and so need to be provided by diet. In addition, milk can

Table 1 Nutrient composition per 100g of pasteurized milk in the UK
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