the kjeldahl method was developed in 1883 by a brewer called johann kjeldahl. A food is digested with a strong acid so that it releases nitrogen which can be determined by a suitable titration technique. The amount of protein present is then calculated from the nitrogen concentration of the food. The same basic approach is still used today, although several improvements have been made to speed up the process and obtain more accurate measurements. It is usually considered to be the standard method of determining protein concentration. Because the kjeldahl method does not measure the protein content directly a conversion (F) is needed to convert the measured nitrogen concentration to a protein concentration. A conversion factor of 6.25 is used for many applications, however, this is only an average value and each protein has a different conversion factor depending on its amino acid composition. The kjeldahl method can conveniently be divided into three steps: digestion, neutralization, titration