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Influence of Hydrocolloids on the Quality of Major Flat Breads: A Review 时间:2017-07-05 13:08   来源:未知   作者:admin   点击: 次 Abstract:Flat breads are popular all over the world. There are several forms of flat bread, which differ in their methods of preparation. In comparison to pan breads, the leavened flat breads have shorter fermentation period. Nowadays, the use of additives has become a common practice in the baking industry. In this paper, supplementation of several hydrocolloids having different chemical structure and diverse origin to the flatbread making process is presented. Hydrocolloids comprise a number of water-soluble polysaccharides providing a range of functional properties that make them suitable to this application. They provide proper texture, control moisture, improve overall product quality and stability, reduce cost, and facilitate processing in the flat breads. Various gluten-free formulations have applied hydrocolloids to mimic the viscoelastic properties of gluten. Hydrocolloids have been used for retarding the staling and for improving the quality of the fresh products. In addition to this, good sensory properties for visual appearance, aroma, flavor, crunchiness, and overall acceptability were obtained.
1. Introduction
In India, Pakistan, Middle East, and North African countries, a large segment of population depends upon whole wheat meal (atta) for production of “chapattis,” whereas refined flour (maida) finds greater application in manufacture of bakery products, for example, breads and biscuits. Wheat (Triticum aestivum) is a common ingredient used in many types of flat breads due to the special functional properties of its constituent protein, gluten. Improving the nutritional value of bread with whole grains has become popular due to its documented positive health effects. The replacement of gluten presents a major technological challenge, as it is an essential structure-building protein. To tackle this problem, hydrocolloids like xanthan gum and guar gum were incorporated in gluten-free flour to mimic the viscoelastic properties of gluten [1].
  (1) Effects of Hydrocolloids on Pasting Properties of Starch Granules. Nonstarch polysaccharides used in formulated food systems are usually called hydrocolloids. Starches and gums (hydrocolloids) are often used together in food systems to provide proper texture, control moisture, and water mobility, improve overall product quality and/or stability, reduce cost, and/or facilitate processing. It is therefore important to understand interactions between starches and food gums that are critical to the functionalities they impart to food products [2]. Hydrocolloids modify gelatinization of starch and extend the overall quality of the product during storage [3].
  Hydrocolloid molecules have a variety of different structures, including differences in branching, flexibility, molecular weight ranges, and ionic charge, all of which influence their behaviour and the rheology of their solutions. This also influences their interaction with leached starch polymer molecules which in some cases increases network formation and in other cases decreases or weakens the network formed by starch polymer molecules. In the rapid-visco-analyser, pasting occurs with continued heating (normally to a 95°C hold temperature) under the shear of the instrument till all order is lost in granules. During pasting, considerable granule swelling and leaching of starch polymer (primarily amylose) molecules occur. A peak viscosity, primarily resulting from swollen granules, is reached. During the 95°C hold, the fragile swollen granules disintegrate under the shear conditions of the instrument, and the viscosity decreases to a trough viscosity (a process called breakdown). As the hot pastes, especially of amylose-containing starches, begin to cool, they become more elastic and develop distinct solid properties; that is, gelation occurs. The transition from a viscous liquid to a gel, when determined by one of the instruments, is called setback; the molecular process that produces setback is known as retrogradation [4].
  The hydrocolloid reduced the availability of water for granule swelling. The increased viscosity thereby increased the shear forces exerted on the swollen granules, thus increasing the breakdown viscosity. Associations between starch polymer molecules and hydrocolloid molecules could be responsible for increase in setback and final viscosity. Hydrocolloid molecules bound water reduced the mobility of the starch chains and thereby retard retrogradation [5]. Effects of guar (GG) and xanthan (XG) gums (0.35–1.0% w/w) on pasting and rheological properties of waxy corn starch (WCS) (6.0% w/w) were studied by Achayuthakan and Suphantharika [6]. Rapid-visco-analyser results indicated that addition of GG or XG to WCS significantly () increased the peak, breakdown, final and setback viscosities, and pasting temperatures. This effect was more pronounced as the concentrations of GG or XG increased. GG had a higher molecular weight but lower intrinsic viscosity than did XG; thus GG chain was more flexible (Table 1).