Ascorbic flour improvement

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. 

There are a few areas in the subjects covered by this book where unfortunately the same words or are used to describe different things. They are gluten and flour improver. In food law a flour improver would cover a substance added to flour to improve its performance, usually in bread. Such a substance is ascorbic acid. In a bakery, the expression flour improver covers a mixture that is added to the dough. In this context a flour improver will contain not only substances like ascorbic acid but also, for example, enzyme active soya flour, emulsifiers and possibly fat. 

After the milling process, any gaseous treatments are applied, any powder treatments, e.g. ascorbic acid, are added, as well as any fortifying ingredients such as calcium sulfate. Different countries have various policies on fortifying flour. In the UK, white flour is fortified with calcium to make up for the calcium lost by not making a wholemeal flour. In the USA, bread is fortified with folic acid. It is possible for an untreated flour to be mixed with a flour improver containing the powder treatments. 

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. 

L-Ascorbic acid is also added to food in essentially a non-nutrient capacity such as a preservative or oxygen acceptor, as an acidulant, as a stabilizer of cured meat color, or as a flour improver. Because of the ene-diol group, it has a marked inhibitory influence on the oxidation-reduction reactions responsible for undesirable color, flavor, and odor development. Its mechanism of action is dependent upon the characteristics of the food or food ingredient, the associated environments, the processing technology, and the storage expectancy of the product. 

Table XXIX. Legal Status of L-Ascorbic Acid as a Flour Improver...

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. 

Some countries have a legal maximum for the amount of L-ascorbic acid used as a flour improver. These may be as high as 200 mg kg in Canada, or as low as 20 mg kg in Uruguay. Many other countries, however, such as the United Kingdom leave the amount added to Good Manufacturing Practice. 

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 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. 

A 6-month-old infant has been fed unmodified cow s milk supplemented with com flour. He was healthy except that he was severely anemic, and an X-ray of his wrist showed retarded bone development. His hemoglobin was only 4.5 g/dL, and he had an elevated serum alkaline phosphatase. He was treated with iron supplements, folate, and ascorbic acid to no avail. Then serum copper analysis was done, and it showed a level of 9 fig/dL (normal is 85-163 /ig/dL). Thereupon his diet was supplemented with copper sulfate, and he showed dramatic improvement. Address the following questions ... 

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