Pasteurisation Health Dictionary

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Pasteurisation: From 1 Different Sources

A method of sterilising milk (see also MILK – Preparation of milk). In many parts of the world, pasteurisation has done away with milk-borne infections, of which the most serious is bovine TUBERCULOSIS, affecting the glands, bones and joints of children. Other infections conveyed by milk are SCARLET FEVER, DIPHTHERIA, ENTERIC FEVER (typhoid and paratyphoid), undulant fever (BRUCELLOSIS), and food poisoning (e.g. from CAMPYLOBACTER, or the toxins of the STAPHYLOCOCCUS).

High-temperature short-time (HTST) pasteurisation consists of heating the milk at a temperature not less than 71·7 °C (161 °F) for at least 15 seconds, followed by immediate cooling to a temperature of not more than 10 °C (50 °F).

Low-temperature pasteurisation, or ‘holder’ process, consists in maintaining the milk for at least half an hour at a temperature between 63 and 65 °C (145–150 °F), followed by immediate cooling to a temperature of not more that 10 °C (50 °F). This has the e?ect of considerably reducing the number of bacteria contained in the milk, and of preventing the diseases conveyed by milk as referred to above.

Health Source: Medical Dictionary
Author: Health Dictionary

Milk

The natural food of all mammalia for a considerable period following their birth. It is practically the only form of animal food in which protein, fat, carbohydrate and salt are all represented in su?cient amount, and it therefore contains all the constituents of a standard diet. Milk is important in human nutrition because it contains ?rst-class animal protein of high biological value; because it is exceptionally rich in calcium; and because it is a good source of vitamin A, thiamine and ribo?avine. It also contains a variable amount of ascorbic acid (vitamin C) and of vitamin D – the amount of the latter being higher during the summer months than during the winter months. Raw milk yields 67 Calories (see CALORIE) per 100 millilitres, in which are present (in grams) 87·6 of water, 3·3 of protein, 3·6 of fat, 4·7 of carbohydrate, and 0·12 of calcium. Heat has no e?ect on the vitamin A or D content of milk, or on the ribo?avine content, but it causes a considerable reduction in the vitamin C and thiamine content.

Preparation of milk Milk may be prepared for food in various ways. Boiling destroys the bacteria, especially any Mycobacteria tuberculosis which the milk may contain. It also partly destroys vitamin C and thiamine, as does pasteurisation. Curdling of milk is e?ected by adding rennet, which carries out the initial stage of digestion and thus renders milk more suitable for people who could not otherwise tolerate it. Souring of milk is practised in many countries before milk is considered suitable for food; it is carried out by adding certain organisms such as the LACTIC ACID bacillus, the Bulgarian bacillus, and setting the milk in a warm place for several hours. Sterilisation, which prevents fermentation and decomposition, is usually carried out by raising the milk to boiling temperature (100 °C) for 15 minutes and then hermetically sealing it. Condensed, unsweetened milk – usually known as evaporated milk – is concentrated in vacuo at low temperature; the milk is then placed in tins, which are sealed, and is sterilised by heat at a temperature of 105 °C. This destroys 60 per cent of the vitamin C and 30–50 per cent of the thiamine. Sweetened condensed milk is not exposed to such a high temperature. The sugar, which prevents the growth of micro-organisms, is added before the condensing, and ?nally reaches a concentration of about 40 per cent.

Dried milk is prepared by evaporating all the ?uid so that the milk is reduced to the form of powder. Humanised milk is cow’s milk treated to render it closely similar to human milk.... milk


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