The role of lipids in determining gas bubble retention in wheat dough

面包是一种基本的主食，它在能量摄入、脂肪和盐的消耗方面对人群的营养状况有重大影响。英国每周生产约8000万条面包，每年价值约25亿GB。由于蛋白质含量和质量更高，英国仍然进口大量用于面包制作的小麦。面包品质由面筋强度和面团气泡稳定性决定，它们分别对面包体积和面团结构有影响。面团中形成的面筋网络控制着面团的弹性，而弹性又控制着面团在证明过程中的上升能力，以及在烘焙过程中的行为。气泡稳定性控制气泡在这段时间内聚合的程度，使其具有典型的英国切片面包的细腻质地。然而，尽管人们现在已经很好地了解了面团强度，植物育种者经常选择特定的面筋蛋白来赋予面团弹性，但气泡稳定性仍然鲜为人知。因此，如果我们能找到改进英国种植的小麦以提供更好的气泡稳定性的方法，我们将能够：--育种者开发质量更好的小麦，--制造商生产质量更好的面包，--减少对进口小麦的依赖--开发更健康的面包，降低盐分和脂肪含量。气泡可以通过在表面形成稳定层的蛋白质、表面活性剂或脂类来稳定。稳定层的分子性质将决定气泡是破裂还是合并。当面团变大时，这一点尤其重要，因为为了增加面包的体积，面团中的气泡会膨胀，最终接触到面包。正是在这一点上，它们要么保持稳定，生产出结构精细的优质面包，要么气泡相互结合，导致面团部分坍塌，质量不佳的面包。研究的重点是小麦面粉中的蛋白质和脂肪成分，但具体情况尚不清楚，因为面团很脆弱，但具有粘弹性，因此在不破坏气泡结构的情况下很难直接研究。然而，正在形成的共识是，小麦脂在很大程度上控制着泡沫的稳定性。小麦面粉含有一系列脂类，所有这些脂类都会吸附在气泡表面，但它们不同的分子结构会对气泡的稳定性产生不同的(正面或负面)影响。因此，面粉的脂肪成分对面团的稳定性至关重要。使用最先进的脂类分析技术，我们将识别稳定面团中气泡的脂类。使用新的表面和生物物理技术，我们将确定不同的脂类如何稳定气泡，以及它们对面团的稳定性和所生产的面包质量的影响。我们将确定不同小麦品种不同脂肪含量的差异，为育种人员制定目标，以改善英国种植的小麦的面包制作质量。此外，改善面包面团中的气泡稳定性将使制造商能够降低面包中的盐、脂肪和乳化剂的水平。这是因为需要盐来改善面团的强度，添加脂肪(如起酥油)和乳化剂来提高气泡的稳定性。提高气泡的自然稳定性将减少对目前生产消费者所希望的面包质量所需的盐和脂肪水平的需求。

Bread is an essential dietary staple, which has a significant influence on the nutritional profile of the population in terms of energy intake, fat and salt consumption. Approximately 80 million loaves are produced in the UK each week in a business worth around £2.5 billion per year. The UK still imports significant amounts of wheat for bread making due to higher protein content and quality. Bread quality is determined by gluten strength and dough bubble stability, which have impacts on loaf volume and crumb structure, respectively. The gluten network formed in dough controls the elasticity of the dough which in turn controls the dough's ability to rise during proving, and its behaviour during baking. Bubble stability controls the extent to which bubbles coalesce during this time, enabling the fine texture typical of UK sliced bread. However, while dough strength is now well understood, with plant breeders routinely selecting for specific gluten proteins which confer high dough elasticity, bubble stability is as yet still poorly understood. Therefore if we can identify ways by which UK grown wheat can be improved to give better bubble stability, we would enable:- - breeders to develop better quality wheats, - manufacturers to produce better quality bread, - reduced reliance on imported wheat - development of healthier bread with reduced salt and fatThe proposal focusses on how the gas bubbles in dough are stabilised. Gas bubbles can be stabilised by proteins, surfactants or lipids forming a stabilising layer on the surface. The molecular properties of the stabilising layer will determine whether the bubbles burst or coalescence. This is particularly important as the dough rises or proves, because to increase the volume of the loaf, the gas bubbles in the dough expand, and eventually come into contact. It is at this point when they will either remain stable, producing a good quality bread with fine structure, or the bubble will coalesce with each other, leading to partial collapse of the dough, and poor quality bread. Research has focused on both protein and lipid components in wheat flour, but the story is not clear, as dough is fragile but viscoelastic and therefore difficult to study directly without destroying the gas cell structure. However, the consensus is emerging that it is the wheat lipids largely control bubble stability. Wheat flour contains a range of lipids, all of which will adsorb to the surface of the bubble, but their differing molecular structures will have different (positive or negative) effects on bubble stability. The lipid composition of the flour will therefore be critical for dough stability. Using state of the art lipid analysis techniques we will identify the lipids which stabilise gas bubbles in dough. Using novel surface and biophysical techniques we will determine how the different lipids stabilise the gas bubbles, and what their effect is on the stability of the dough and the quality of bread produced. We will determine the variations in the amounts of the different lipids occurring different wheat varieties to develop targets for breeders to improve the bread making quality of UK grown wheat. In addition, improving the gas bubble stability in bread dough will allow manufacturers to reduce the levels of salt, fat and emulsifiers in bread. This is because salt is required to improve dough strength, and fat (as shortening) and emulsifiers are added to improve gas cell stability. Increasing the natural stability of the gas bubbles will reduce the need for the levels of salt and fat currently required to produce the quality of bread desired by consumers.