Staling of Bread: Role of Amylose and Amylopectin and Influence of Starch‐Degrading Enzymes

Abstract

Cereal Chem. 80(6):654-661The present investigation aims at understanding the mechanism of bread firming during staling. Changes in the starch fraction due to the addition of amylases and their influence on the texture of bread crumb were studied during aging and after rebaking of stale bread. Pan bread was prepared by a conventional baking procedure. The influence of three different starch-degrading enzymes, a conventional a-amylase, a maltogenic a-amylase, and a b-amylase were investigated. The mechanical properties of bread were followed by uniaxial compression measurements. The microstructure was investigated by light microscopy, and starch transformations were assessed by differential scanning calorimetry (DSC) and wide-angle X-ray powder diffraction. Firming of bread crumb and crystallization of starch are not necessarily in agreement in systems with added amylases. Reorganization of both starch fractions, amylopectin and amylose, and the increase of starch network rigidity due to increase of polymer order are important during aging. Starch-degrading enzymes act by decreasing the structural strength of the starch phase; for instance, by preventing the recrystallization of amylopectin or by reducing the connectivity between crystalline starch phases. On the other hand, starch-degrading enzymes may also promote the formation of a partly crystalline amylose network and, by this, contribute to a kinetic stabilization of the starch network. Based on the results, a model for bread staling is proposed, taking into account the biphasic nature of starch and the changes in both the amylose and amylopectin fraction.

Changes in the Texture and Viscoelastic Properties of Bread Containing Rice Porridge during Storage

“…Bread staling is a significant factor that leads to decreases in bread texture quality. 8) Little information is available as to how the physical properties of bread containing gelatinized rice starch change over time. Our objective in this study was to investigate the effects of rice porridge on the texture and viscoelastic properties of bread and to compare them with those of wheat flour and rice flour bread during storage.…”

Effect of Brea Gum on the characteristics of wheat bread at different storage times

“…This indicates that the water absorption of the dough with BG was higher. This effect was due to the water retention ability of this polymer resulting from the hydrophilic nature of most gums (GUARDA et al, 2004;CHRISTIANSON et al, 1981;COLLAR;ARMERO;MARTÍNEZ, 1999;GURKIN, 2002;TWILLMAN;WHITE, 1988). Perhaps, this behavior can demonstrate that during cooking, the hydrocolloid forms a network that could act as a barrier to the diffusion of gases, which in turn would reduce vapor losses resulting in higher moisture content of crumb bread Crumb moisture content Moisture content was determined in fresh and stored samples, according to the AACC official method (method 925.10) (AMERICAN..., 1995).…”

“…The starch in the crumbs supplemented with BG, is provided with a certain amount of water that is less than that of the control crumb, but enough to act as a plasticizer in the reorganization of the amylopectin molecule. Rogers et al (1988) concluded that starch retrogradation and hardening of the crumb are uncorrelated with each other in a certain range of moisture contents and, according to several authors, the moisture content close to 40% would highly favor starch retrogardation and bread firming (DAVIDOU et al, 1996;HE;HOSENEY, 1990;ROGERS et al, 1988;). …”

“…Bread quality loss takes place due to staling that begins just when loaves are taken out from the oven (BÁRCENAS; ROSELL, 2005). Staling involves several physical and chemical phenomena, recristallyzation of the amylose, and amylopectin (HUG-ITEN; ESCHER; CONDE- PETIT, 2003;ZOBEL;KULP, 1996), loss and redistribution of water (CZUCHAJOWSKA; POMERANZ, 1989;LAI, 1986), and protein-starch interaction (CHAMP; FAISANT, 1992;ELIASSON;LARSSON, 1993;EVERY et al, 1998) are the most important ones.…”

Application of amylographic method for determination of the staling of bakery products

“…Some other authors obtained seemingly contradicting results when either decreases (Yasunaga et al 1968) or increases (Xu 1985) were found out in viscosity with storage times. Bakery improvers such as enzymes (amylases, lipases, proteases, pentosanases), emulsifiers, hydrocolloids, and their blends serve as additives to improve technological (rheological) and texture properties of dough and slow down the staling of bread and bakery products (Hug-Iten et al 2003;Bárcenas & Rosell 2005;Jiang et al 2005;Moayedallaie et al 2010;Rosell & Santos 2010;Patel et al 2012, etc.). The addition of improvers (mostly in ppm amount) affects the standard quality of dough and bread and also the staling process of bread.…”