Bread, brown/white

One property of the flour that is controlled by the miller is the extraction rate. Wholemeal flour has a 100% extraction rate, with brown, white and patent white having progressively reduced extraction rates. One obvious difference is the colour. Another is that the quality of the protein increase towards the middle of the wheat berry from which patent flour is produced. Thus, patent flour is sometimes used not to produce whiter bread but in products like hlo pastry or West Indian patties where the strength that patent flour gives is important and the colour is irrelevant. 

Describe the reaction engineering of a kitchen toaster. The reactions are thermal drying (which alone makes stale bread) and thermal decomposition and oxidation of starch, which requires temperatures of -300°C. [Recall that the bread appears white until it is nearly done, and then it browns quickly and blackens if left in too long. Recall also that good toast has a brown layer < 1 mm thick while the interior is still white and soft. The control of temperature profiles and heat transfer aspects are essential in producing good toast.]... 

A number of studies have shown that zinc, as compared to other minerals, is poorly utilized from phytate-contalning foods. The relative BV of zinc in a number of phytate-contalning foods was recently examined by Franz et al ( ). Each product was prepared as for human consumption and Incorporated into a semi-purifled diet fed to rats. Whole corn and brown rice had a low relative BV (0.58 or less compared to 1.00 for zinc in zinc sulfate) while wholewheat flour and unleavened wholewheat bread had medium values (0.63-0.74). Refined cereal products such as white flour, leavened and unleavened white bread and white rice (all low in phytate) had high relative BV (0.89-1.08) as did leavened wholewheat bread... 

Current British fortification of bread and flour is restricted to fortifying white and brown flour and bread with those materials that would be present in wholemeal bread or flour. 

Brown flour is a term that covers the extraction rates above 70% and below 100%, i.e. between white and wholemeal flour. Unlike wholemeal flour the full range of flour improvers are legal. The sale of brown bread is lower than that of wholemeal. Some nutritional thinking points to... 

Brown and wholemeal bread are generally made in a similar way to white bread except that a higher level of fat is normally used, e.g. 1.5% of the flour weight as fat, compared with 1 % for white bread. In making wholemeal or brown bread by the CBP process the fat level must be raised. It is only possible to make wholemeal bread by the CBP because... 

These products were developed to offer the consumer a fibre-enhanced bread that still tasted like white bread rather than brown or wholemeal. Various kibbled grains, e.g. kibbled rye and kibbled wheat are added. The addition can be made either in the bakery or at the flour mill. 

The brown or whole meal bread diets employed by previous investigators were often variable in calcium and phytate intakes, not only between individuals, but by the same individual subjected to different diet treatments. Nevertheless an estimate of the molar ratio of phytate/calcium in the brown or whole meal bread diets used by McCance and Widdowson (UO), Walker et al. (11) and Reinhold et al. (2, 12) is 0.25 or greater. These investigators observed either negative or less positive calcium balance and apparent absorption when the brown bread diets were consumed compared to white bread diets with phytate/calcium molar ratios less than 0.05. Our results support their findings. Reinhold et al. (2) and McCance and Widdowson (33) used sodium phytate in some studies as well as whole wheat bread and observed similar results. 

More than 40 years ago, calcium absorption from brown (whole wheat) bread which was fed to human subjects was found to be poorer than was that when white (extracted wheat flour) was fed 04,5). Since then, many studies have sought to define the extent of inhibition of calcium intestinal bioavailability by various forms of dietary fiber with mixed results and conclusions (6-18). 

Since in particular the cracker-like crust odor note was lacking in the synthetic mixture, it was concluded that the character impact compound for this odor note occurs in a concentration in the bread too low to be detected by headspace analysis. Later on the basis of its aroma quality and its very low odor threshold of 0.04 ppb (water), Mulders et al. (19) proposed 2-[(methyldithio)methyl] furan (4 in Figure 1) as the compound which should be responsible for the "golden brown" crust aroma of white bread. 

Be wary of brown bread and whole-grain products—if it doesn t say 100% whole grain, it s probably predominantly white flour. As a better option, try one of the bread recipes in chapter 8. 

Based on USDA estimates of per capita consumption of wheat flour, one-third of the adult woman s Recommended Dietary Allowance (RDA) for iron could be obtained if we consumed whole wheat products Q). The iron in wheat, however, is thought to be poorly bioavailable to humans, primarily attributable to the effect of phytate. British investigators found that the iron balance of individuals was lower when they ate largely whole meal bread than when they ate bread made with white flour (2). When the test bread made with white flour contained either sodium or ferric phytate, postprandial serum iron rise was depressed ( ). They theorized that the phytate present in the brown bread formed an insoluble iron salt and rendered the iron unabsorbable. That theory was supported by the work of Moore et al. (4) at Washington University, who tested the response of anemic individuals administered therapuetic doses of ferric... 

The color of the semiconductor in your computer chip or the color of your implanted biomaterial or pharmaceutical tablet is of little consequence. The color of your toothpaste, face cream, beverage, or food is another matter. Consumers are used to the manufactured brands of brilliant white toothpaste with blue, red, or green stripes. Brown is not a popular color for bathroom products (see the handbook review Porous Silicon for Oral Hygiene and Cosmetics ). There are brown and even black popular foodstuffs - think of bread, peanuts, cereals, chocolate, coffee, and marmite (see handbook chapter Porous Silicon and Functional Foods ). However, these are in the minority, and once again the consumer associates specific foods with specific colors. 

The relative merits of white versus brown bread have been disputed since the time of Hippocrates. The subject was once again brought to the fore in the early 1970s as the result of work by Cleave, Burkitt and others who suggested that dietary fibre, or rather its lack, is implicated in a great variety of diseases. 

Controversy has been raging for many years as to whether, from the nutritional point of view, white or brown bread is better. Brown bread made from high extraction flour contains more protein, calcium, iron, B vitamins and fibre than white bread but its nutrients tend to be less well digested and absorbed. The case for white bread is based on its more attractive appearance, finer texture, better baking and keeping qualities and also its lower content of fibre and phytic acid which are responsible for the poorer utilization of nutrients. In Britain, where bread is only one of many articles of diet, nutritional differences between wholemeal and fortified white flours are of little practical significance. However, such differences could become important if bread ever became the single staple food. 

Fig. 15.50. Formation of 2-acetyl-l-pyrroline ( - ) and 2-acetyltetrahydropyridine (o-o) on toasting white bread (according to Rychlik and Grosch). Abscissa intensity of browning (8 very strong).

BREAD, WHITE CORNMEAL. DEQERMED RICE, BROWN RICE. WHITE... 

---