Cysteine flour improvement

The flour improver would contain sufficient L-cysteine hydrochloride to give 35 mg kg-1 of flour (equivalent to around 27 mg kg-1 of L-cysteine) with sufficient potassium bromate to give 25 mg kg-1 of flour and sufficient ascorbic acid to give 50 mg kg-1 of flour. The above assumes a flour of 12% protein that has had added to it up to 20 mg kg-1 potassium bromate. Alternatively, with an untreated flour all the potassium bromate would be in the improver. 

Fig. 15.34. Reactions involved in flour improvement by ascorbic acid (according to Grosch and Wieser, 1999) Asc, ascorbic acid DHAsc, dehydroascorbic acid AO, ascorbic acid oxidase GSH-DH, glutathione dehydrogenase GSH, reduced glutathione GSSG, oxidized glutathione CSH, cysteine CSSC, cystine PSSP, gluten proteins...

The permitted use level in bread flour in the UK is 75 mg kg 1 in all bread flour except wholemeal and biscuit flour. The use in biscuit flours is permitted at 300 mg kg-1, except where sulfur dioxide or sodium metabisulfite is used. L-Cysteine is also used in pastry as a pastry relaxant. In both pastry and biscuits, not too surprisingly as the chemical action is the opposite of that in bread improvers, the reducing agents... 

L-Cysteine is normally added as L-cysteine hydrochloride or L-cysteine hydrochloride monohydrate. When the ADD process was in use it was incorporated in a compound improver. If L-cysteine is used as a pastry relaxant it is supplied mixed with either soy flour or an inactivated wheat flour. This of course aids dispersion and the measurement of very small quantities. 

Chemical additives used in baking and not already present in flour in the required quantities are added to the dough in the form of a premix. Osborne [17] used NIR in a model experiment to determine three bread improvers (ascorbic acid, L-cysteine, and azodicarbonamide) in admixture in a starch diluent. Although the accuracy of each calibration was not satisfactory for their determination at the levels encountered in bakery premixes, the results were sufficient to indicate the potential of NIR for this type of application. This potential has been realized in the determination of nicotinamide in nutrient premixes where Osborne [18] obtained excellent results by NIR compared with high-performance liquid chromatography. The NIR calibration involved a ratio of second derivatives at 2138 nm, corresponding to a nicotinamide absorption band, and 2070 nm as a reference. 

Additives are used in flour milling and bread-making to improve the texture and colour of breads ( improvers such as potassium bromate and cysteine—a naturally occurring amino-acid), and the texture of cakes " (chlorine, bromate and various emulsifying agents). 

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