home *** CD-ROM | disk | FTP | other *** search
- Treatment of food to reduce the number of
- microorganisms it contains and so protect
- consumers from disease. Harmful bacteria are
- killed and the development of others is
- delayed. For milk, the method involves
- heating it to 72 degrees C/161 degrees F for
- 15 seconds followed by rapid cooling to 10
- degrees C/50 degrees F or lower. The
- experiments of Louis Pasteur on wine and beer
- in the 1850s and 1860s showed how heat
- treatment slowed the multiplication of
- bacteria and thereby the process of souring.
- Pasteurization of milk made headway in the
- dairy industries of Scandinavia and the USA
- before 1900 because of the realization that
- it also killed off bacteria associated with
- the diseases of tuberculosis, typhoid,
- diptheria, and dysentery. In Britain,
- progress was slower but with encouragement
- from the 1922 Milk and Dairies Act the number
- of milk-processing plants gradually increased
- in the years before the World War II. In the
- 1990s nearly all liquid milk sold in the UK
- is heat treated and available in pasteurized,
- sterilized, or ultra-heat-treated (UHT) form.
- UHT milk is heated to at least 132 degrees
- C/269 degrees F for one second to give it a
- shelf life of several months.
-