Use of sulphur analysis in the prediction of the protein value of middle‐eastern diets

A rapid procedure for the analysis of sulphur in foodstuffs is described and is compared with the barium chloranilate procedure. The prediction of the protein value of Middle‐Eastern diets from the S : N ratio has been compared with that obtained by rat‐feeding experiments. the agreement found depends more on the relationship with protein quantity than with any quality measurement. Furthermore, the correlation between S : N ratio and SAA (sulphur‐containing amino acid) score was not significant for 22 diets where SAA data were available. Calculation shows that the proportion of total sulphur from methionine and cystine can show large variations both for individual food components and also for mixed diets. the S : N prediction procedure does not appear to be suitable for Middle‐Eastern diets.