Flour ascorbic acid addition

Vitamin C, or ascorbic acid, is surely the best known of all vitamins. It was the first vitamin to be discovered (1928), the first to be structurally characterized (1933), and the first to be synthesized in the laboratory (1933). Over 200 million pounds of vitamin C are now synthesized worldwide each year, more than the total amount of all other vitamins combined. In addition to its use as a vitamin supplement, vitamin C is used as a food preservative, a "flour improver" in bakeries, and. an animal food additive. 

The situation with wholemeal flour is refreshingly simple. Flour treatments are banned and there are no statuary additions. The addition of ascorbic acid to wholemeal flour is forbidden but the use of ascorbic acid in wholemeal bread is allowed. Presumably, it was thought beneficial to allow the change so that the Chorleywood plants could make wholemeal bread. The ascorbic acid presumably goes in as an improver with other ingredients. 

It has been found that glucose, sucrose, casein, albumin, sodium chloride, flour groats, and starch stabilize ascorbic acid (vitamin C).771 The addition of 5% of starch inhibits the decomposition of ascorbic acid.772 Studies on the stability of ascorbic acid, sodium ascorbate, erythorbic acid, and sodium erythorbate showed that some stabilization is observed after the addition of 8% starch.773 It was reported that the interaction is purely physical in nature.774... 

L-Ascorbic acid may also be used as a food additive in circumstances where it is not expected to provide any increase in the nutritious nature of the food, but where it is present to prevent oxidation, as a preservative, to increase acidity, as a stabiliser, or as a flour improver. It is very often used as an additive for all these purposes. 

L-Ascorbic acid is very widely used in bread baking, where it is present as a flour improver . In practice, this means that the addition of L-ascorbic acid improves the bread texture and the size of the resulting loaf, the dough has greater elasticity, increased gas retention. 

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. 

An ascorbic acid oxidase (AO) occurs in wheat flour (Table 15.25), which oxidizes L-threo- and D-erythro-2iSCOYhic acid at comparable rates. In addition, a substance has been found in flour extracts which oxidizes L- /ir 6>-ascorbic acid at pH 10 at a maximal rate. In comparison with AO, this activity does not decrease on incubation with proteases nor is it inhibited by the addition of the AO inhibitors KCN and NaF. It obviously catalyzes a nonenzymatic oxidation of ascorbic acid. 

Fig. 15.31. Rheological properties of wheat dough as a function of different concentrations of added L-threo-ascorbic acid (Asc) (according to Kieffer, unpublished). Tensile tests with dough made of 10 g of flour of the variety Flair. Addition of Asc (mg/kg) 20 o-o), 40 ( - ), 80 and 120 (A-A), 160 (A-A). Control without additive —...

Flours are commonly treated with additives and enrichment premixes to standardize quality and meet regulations. The treatments commonly consist of flour bleaching, maturing or aging, enzyme supplementation, and addition of the enrichment to supplement selected minerals and vitamins. Hard wheat flours are, in some instances, oxidized with azodicarbonamide, ascorbic acid and/or, in some countries, with potassium bromate in order to improve functionality. Soft wheat flours are in some instances chlorinated to produce bleached cake flours. The normal range of chlorination ranges... 

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