POWERHOUSE COLLECTION

Portable pH meter used by Westons Foods

Object No. 2005/98/1

This pH meter was made in Melbourne in the 1950s and used at the George Weston biscuit factory in Sydney. Quality control scientists randomly selected partly cooked dough from the production line, mixed it with distilled water and inserted the meter's glass electrode into the resulting solution. The pH reading, a measure of the acidity of the solution, indicated the proportion of leavening agent left in the dough and hence the time required to complete the cooking process. Debbie Rudder This Australian made pH meter represents an early model of accurate pH determination. Although no date is marked on the instrument, its design is similar to the first easy to use and commercially successful pH meter invented by Dr Beckman in the USA in 1934 and manufactured from 1935 to around 1950. From comparing phone directory information to the N. L. Jones Company's address information in the unit, the date of this instrument may be from 1952-1957. The pH of food and drinks often yields information about the quality of food such as its freshness and whether it will taste sweet or bitter. pH measurement was the prime control method of the baking operation employed in the manufacture of biscuits. This instrument was used for between 20-30 years by George Westons Foods Ltd, Biscuit and Cake Division, 4 Lyons Road, Camperdown, New South Wales, as a critical control of their biscuit baking operations. This type of pH meter was replaced by much faster technologies for monitoring food production. In association with the Marconi moisture meter also donated by Westons, the pH meter represents one of the basic devices used for quality control testing by this section of the food industry. While not rare, this pH meter is representative of Australian multiple production of a widely used type of scientific instrument and is an example of instrument design from the 1950s.