Bread water content

Bread doughs become heated by the mixing process, and the yeast may begin to work too soon. The water content of the mix maybe chilled, or the larger machines may have water-cooled jackets to take away this heat. 

These soft pretzels are bread and have a shelf life like bread. The only way of extending the shelf life is to reduce the water content to around 2-3%. They remain popular and are still made. 

Fig. 16.—Mass, Q (mg/mL), of water-soluble products as a function of the content of amylose in starch. Variety of starch P, potato AM, amylomaize M, maize R, rice H, haricot bean MN, manioc WM, waxy maize B, bread wheat. Point P relates to potato starch after correction of the result attributable to high water content in that source (from Ref. 102).

Thermo-mechanical analysis (TMA)26 and DMTA292 have been used to study the viscoelastic properties of bread, a composite two-phase system. The moisture dependence of Tg was similar to that of pure amorphous starch and gluten.242,282 293-295 At the moisture content of bread, water exerts its full plasticization effect on the composite polymer matrix, reducing the effective Tg to about -10° to - 12°C,26,292 well below normal shelf life storage temperatures of this product. 

Figure 1-16 Specific Heat of Bread of Different Water Contents (Indicated as %) as a Function of Temperature. Source. From L. Riedel, Calorimetric Studies of the Freezing of White Bread and Other Flour Products, Kaltetechn, Vol. 11, pp. 41—46, 1959.

The lipids, although present in a very small amount, are also of critical importance for the bread making process. The lipids themselves form Hu, La and L3 liquid-crystalline and liquid phases respectively with increasing water content. 

Four formulations were used to produce French bread dough with different ascorbic acid quantities, as listed in Table 27.1. AACC 54-21 (AACC, 1995), a commercial bakers flour (Moinho Pacifico, Brazil) with a water content of 13.60% and farinograph water absorption of 65.60%, was used for all formulations. 

The water content of the French bread dough was determined according to AACC 44-15A in five replicates (AACC, 1995). This analysis provided the total amount of water of the dough (Wtot)-... 

Matuda, T.G., Parra, D.R, Lugao, A.B., and Tadini, C.C. Influence of vegetable shortening and emulsifiers on the unfrozen water content and textural properties of frozen French bread dough, Lebensm. Wiss. TechnoL, 38, 275, 2004. 

As the temperature is lowered further, a point is reached where many physical properties of the polymer, such as elastic moduli, viscosity, and specific volume, fall dramatically over a narrow temperature range. This is the glass transition temperature, Tg, which was discussed in Chapter 6. At this temperature, segmental motions of polymer molecules practically cease. It appears that the temperature of around -20°C, at which crumb firming rate becomes negligible, may correspond closely to the Tg of amy-lopectin at the water content of bread. 

YH Roos. Phase transitions and unfreezable water content of carrots, reindeer meat and white bread studied using DSC. J Food Sci 57 684-686 (1986). 

Fig. 15.43. The reducing sugar content in wheat bread crumb as affected by water content of dough (according to Wassermann md Doerfner, 1971).

The water content of aU cereals is virtually the same as the water content in flours and dry pasta products (9-14%). White bread usually contains 35-36% of water there is more water in rye bread (38-45%). 

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