Wheat. Peter R. Shewry. Читать онлайн. Newlib. NEWLIB.NET

Автор: Peter R. Shewry
Издательство: John Wiley & Sons Limited
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Жанр произведения: Биология
Год издания: 0
isbn: 9781119652595
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status in Central Asian culture; it must be kept upright and cannot be placed on the ground or thrown away. It must be torn by hand rather than cut. At a wedding ceremony, the bride and groom both take a bite from a non and finish it the next day as part of their first meal as man and wife. Similarly, when a soldier goes to war, he takes a bite of non as he leaves. His family will then hang the bread up and only take it down once he is safely home. Uzbek‐style non is old enough to have been mentioned in the Epic of Gilgamesh (tales of the ruler of the Sumerian Kingdom of Uruk), dating from over 4000 BP.

Photos depict a few examples of breads consumed around the world.

      Source: All images from the author's collection except (d), which was provided by Dr. Anil Gaddameddi (Hyderabad, India).

      1.4.3 Bread Today

      Breads are produced in a vast array of forms, many of them restricted to specific geographical regions. They can be broadly divided into two types: high specific volume breads such as Western pan breads (although some such as French baguettes, have lower volumes) and low specific volume flat breads, which are dominant in the Middle East and Asia. Flat breads include both leavened and unleavened types, while both Western and flat breads can be leavened with yeast or sourdough systems. They also vary in how they are cooked. Although baking is the most common method, they may also be steamed or fried.

      High‐volume Western breads are baked on the bottom or shelves of an oven, either unsupported (hearth breads) or in a pan which supports the loaf leading to a higher volume (pan breads). Most Western breads are produced using bakers' yeast ( Saccharomyces cerevisiae ) for fermentation, but sourdough systems are becoming increasingly popular, usually as artisanal hearth breads. Yeast‐based systems use well‐defined genetic strains of yeast that are purchased from commercial producers and, in most cases, used fresh for each batch of bread. Hence, their effects are well understood and reproducible across processes. By contrast, sourdough systems use combinations of natural lactobacilli and yeasts. In artisan systems, the sourdough cultures are perpetuated by carrying starters over between batches of dough, while for large‐scale production they may be purchased from ingredient supplies. In both cases there is wide variation in the compositions of microorganisms and their corresponding effects on the dough and bread. This poses a major challenge for researchers and food manufacturers as research carried out on one sourdough system may not apply to other systems. Nonetheless sourdough systems have become more widely used in Western‐style wheat breads over the past two decades, as part of the trend towards increased consumption of traditional foods (with perceived health benefits). Hence, there is a flourishing sourdough research community with a rapidly increasing number of publications. However, because of the issues discussed above, the generic significance of much of the work is difficult to assess.

      The effects of fermentation, whether using yeast or soughdough systems, will depend on the conditions employed. In traditional breadmaking systems, the dough may be fermented overnight, or even longer. By contrast, most of the high‐volume factory bread produced in the UK and many other Commonwealth countries is produced using the Chorleywood Breadmaking Process (CBP), or processes related to this. This is a very rapid method, with the mixing and dough development being carried out in a single operation using a large amount of yeast, high energy, and control of the headspace pressure during mixing. After this, only short intermediate and final proving periods are required before baking. The effects of fermentation on the health benefits of breads are discussed in Chapter 9.

      Faridi (1988) lists over 50 major types of flat bread; only a few of these can be mentioned here. Arabic bread (often called pita) is a yeast‐leavened flat bread from the Middle East and North Africa, which can be produced from white or high extraction (bran‐enriched) flours. It is baked for a short time on the bottom of an oven at high temperature; this turns the water into steam, causing the bread to puff up, separating the two sides to form a pocket in the baked loaf (Figure 1.19d).

      Other flat breads in the region are Yemeni maloung, which is cooked on the inner wall of a tandoor (Figure 1.19b), and sangak, which is a large thin sourdough white bread baked on a bed of small stones in Iran (Figure 1.19f). One of the most popular breads in Iran is lavash, a white sourdough bread that exists in a range of forms including in thin crispy sheets which can be dried and stored in plastic bags for weeks (Figure 1.19h).

      About 80% of the bread consumed in the Indian sub‐continent is chapati (Figure 1.19d), an unleavened bread which is made from atta flour (about 95% flour extraction) and water and is cooked on a hotplate. Puri is made from a similar recipe to chapati but is fried, whereas paratha is cooked on a hotplate but contains salt and about 40% fat. Unlike these breads, naan is made from white flour, is yeast fermented, and then cooked on the inside of a tandoor.

      1.4.4 The Fall and Rise of Whole Grain Foods

      The adoption of roller milling made white flour available to all the population. This led to massive changes in the diet of working people with coarse wholemeal or brown breads being almost completely replaced by white products in the UK by 1880 CE. Although the science of nutrition was then in its infancy, concerns were nevertheless expressed about the impact of this change in diet on the health of the population.

      An early supporter of wholemeal bread was Sylvester Graham (1794–1851), an American Presbyterian minister, who proposed a lifestyle that combined temperance, vegetarianism, and the consumption of whole‐grain bread. His views were expounded in his preaching and in publications, notably Lectures on the Science of Human Life, published in 1849. They led to a movement referred to as Grahamism and inspired the development and marketing of Graham flour, Graham bread, and Graham crackers. The last of these are still widely consumed in the USA. However, Graham did not endorse any products or benefit financially from their sale.