CHEMICAL-CHANGES DURING COOKING OF WHEAT

Chemical changes occurring during the cooking of wheat have been measured in whole grains and in ground wheat. Changes in the gross composition of whole wheat (decreases in the levels of reducing sugars and amino acids) suggested that the Maillard reaction was taking place. Since the water activity of wheat changes during cooking, experiments were performed to study the effect of initial water activity on a number of parameters. Water production, which is symptomatic of early stages in the Maillard reaction, was greatest at a(w) = 0.45. Addition of sulphur dioxide had no effect on these results. Volatile production was greatest at a(w) = 0.64 but comparison of the volatile profiles at different water activities was not possible due to high intra- and inter-sample variation. There was little sign of typical Maillard volatiles in these samples. Colour development decreased with increasing water activity and sulphur dioxide had little effect, suggesting that Maillard and phenolic oxidation play minor roles in colour formation. Although the Maillard reaction seems to occur in heated wheat samples, its role in colour and volatile formation during cooking appears to be minor.