Review of Literature Different Hydrocolloids as Bread Improvers and Anti Staling Agents .

Abstract

Some definition of staling:Broadly speaking, bread staling refers to all changes that occur in bread after baking. Changes occur in both the crumb and the crust of the bread. The increase in crumb firmness has probably been used to the largest extent by investigators following bread staling. Other changes, however. Such as loss of flavor, decrease in water absorption capacity, amount of soluble starch and enzyme susceptibility of starch, increase in starch crystalline and opacity.Firmness is an important sensory attribute of bread. Bice and Greddes (1949) concluded that firmness and crumbliness are related closely to organoleeptic assessment of staleness . Literature on the staling of bread and on the methods for the measurements of the extent of the staling are scare. Type of anti-staling :Today, several anti-staling agents are used in the bread making industry. These anti-staling agents have different mechanisms, which provides the opportunity to influence the properties of the product: 1-Water content of dough and bread :Water content of dough and bread affects the properties of different chemical components of dough and bread. In the oven, heating rate of the dough piece and baking temperature affect the swelling and gelatinization of starch and, as a consequence the crumb structure .Water is assumed to have a significant role in the staling process. Water is more abundant in the swollen amorphous regions of starch,facilitating local polymer chain mobility (plasticization) and sub-sequent crystallization and retrogradation (Chinachoti and Vodovotz,2001).Water distribution within regions in gluten, amorphous and crystalline starch is assumed to play an important role in starch and gluten rigidity. 2-Sourdough fermentation :Sourdough fermentation is used to improve the texture, volume and shelf-life of breads (Brummer and Unbehend, 1997;Corsetti et al., 1998 ). Combined use of exogenous enzymes and sourdough in the same baking process has been reported to enhance rate of acidification, improve bread volume and retard white wheat bread staling (Martınez-Anaya et al., 1998;Corsetti et al., 2000 ). 3-Hydrocolloids and its role:Hydrocolloids are widely used as additives in the food industry, because they are useful for modifying the rheology and texture of aqueous suspensions (Dziezak, 1991). Hydrocolloids due to their high water retention capacity confer stability to the products that undergo successive freezethaw cycles (Lee,et al. 2002;Sanderson, 1996). Today, several antistaling agents are used in the bread making industry. These antistaling agents have different mechanisms, which provides the opportunity to influence the properties of the product. Locust bean gum (LBG), methyl cellulose and