Production: Quality control

John James and Mary Ann Sainsbury began trading at a time when tainted and adulterated food was a national concern. Sainsbury's founding principle was reflected in the Chapel Street, Islington shop sign, which read 'Quality perfect, prices lower'.

When Sainsbury's new factory opened in 1936 it included quality control laboratories so that the goods produced could be regularly tasted and analysed. Arthur Sainsbury also insisted that production line workers be provided with a clean hand cloth each day. Quality was tightly controlled in the factory - whole batches of pies would be rejected if just one was not up to standard.

As Sainsbury's range of own-brand products increased, the quality control systems developed. By the mid-1950s, the Blackfriars headquarters included separate chemical and microbiological laboratories and undertook research as well as development and testing. Equipment was also kept up-to-date and included an electronic polarograph for detecting trace metals which 'does in minutes, work which once required analyses lasting several days'.

In 1964, laboratories were also introduced at the new Basingstoke depot to carry out 'on-the-spot' analyses before distribution to the shops. Quality control was equally important in stores: in 1968 perishable items were given a shelf life code using a systems of letters from the phrase 'JS for Quality'. By 1976, Sainsbury's described its Blackfriars lab as 'probably the most modern laboratory of any food retailer in Europe'. As well as the food technologists, there was also a dedicated Home Economics department for testing recipes under domestic conditions.

Today, Sainsbury's continues to ensure it products are of the highest quality, through its Food Centre at Holborn and team of Food Safety Managers who carry out frequent visits to all suppliers. There are also 'mystery shoppers' who buy products from stores for testing as an additional check. Sainsbury's was the first supermarket to conduct large-scale trials of BSE tests and maintains an active role in trialling and developing new technologies.