Citric acid was isolated from lemon juice in 1784, but its composition was made clear only after almost a century. The procedure for obtaining citric acid from citrus juice (above all, lemon, lime and bergamot), also known as the Scheele process, consists of two parts: the precipitation of citric acid in the form of calcium citrate, and then the 'decomposition' of the citrate itself, which permits the production of a citric solution of sufficient purity to allow its crystallization. For a long time the Scheele process was used, above all, in England. From the eighteenth century onwards, there was the production in Sicily of agrocotto, a dark liquid obtained by concentrating lemon juice, containing around 40 per cent citric acid. This production was aimed at supplying the industry that was developing in England. In truth, it seems to have been a sort of agrocotto that was produced in Roman times for medicinal purposes, prepared from the endocarp of the citrus fruit. Later, with the aim of having available a more suitable raw material, English manufacturers encouraged the production of calcium citrate (corresponding to the first phase of the Scheele process). This production was begun in Sicily around I860, and in the course of a few decades had replaced that of agrocotto. At the end of the nineteenth century, the production of agrocotto and calcium citrate had also gained importance in the British West Indies. In the years preceding the First World War, Italy was capable of supplying 90 per cent of world demand for calcium citrate. In 1913 in Sicily, production was equivalent to 6,000 metric tonne, in addition to around 250 metric tonne of agrocotto\ in 1918 production was 9,087 tons. In the same period, direct production of citric acid also started in Sicily. In 1908 Italy imported citric acid (164 tons), whereas, in 1916 it exported over 1,000 tons. In the period between 1899 and 1915 citric acid was also produced in California (Braddock, 1999). Starting from 1918, processes for the production of citric acid were put into operation that were based on the fermentation of molasses from sugar cane and sugar beet. The biological product became more and more popular, so that, in practice, today citric acid is no longer produced from citrus fruit.
Was this article helpful?