Mining diversity of cereal (wheat) fibre to improve the nutritional quality of wheat

小麦是英国种植的主要粮食作物。很大一部分用于人类消费，使其成为人类饮食中卡路里、蛋白质、矿物质、维生素和膳食纤维的重要来源。食用纤维与降低心血管疾病、某些类型的癌症（如结肠癌和乳腺癌）和2型糖尿病的风险有关。谷类食品，尤其是面包，是英国人饮食中的主食，也是碳水化合物的主要来源之一。虽然有动力增加全谷物和全麦产品的消费，但许多消费者仍然更喜欢白面包的质地和外观。制造商正在通过加工来解决这个问题，使用新型纤维衍生成分和白小麦，让添加了麸皮的面包看起来像白面包。然而，这样做的营养价值还有待于对每种产品进行证明。白面包是英国的一种重要食品，但由于它是淀粉类食物，会迅速分解为葡萄糖，因此血糖生成指数（GI）很高。全麦面包含有更高水平的膳食纤维，被认为更健康，但在英国只占面包的一小部分。膳食纤维含有两种成分；可溶性和不可溶性，小麦中的主要可溶性成分是阿拉伯木聚糖（AX），它占小麦胚乳细胞壁聚合物的70%。纤维起作用的机制尚不清楚，尽管有证据表明它的作用是改变胃和肠道中物质的粘度，减缓营养物质的吸收。这项资助的目的是通过研究改变AX结构和溶解度的影响来确定纤维的作用机制。我们将首先（在洛桑）种植四种小麦系，这些小麦系在之前的洛桑和IFR合作工作中已经显示出具有非常不同的AX含量。这些将被磨成面粉，并在英国坎登BRI烘焙中心使用标准方法制成面包。研究人员将使用IFR和洛桑研究所开发的新方法，研究谷物、面粉和面包在制作面包的过程中AX发生了什么变化。此外，我们将开发和统一IFR和伯明翰的现有设备；将IFR的模型胃和伯明翰的模型肠制成一种可以用来模拟胃和十二指肠消化的形式，并研究细胞壁成分在模拟消化过程中的行为。通过这些方法，我们将能够识别和解释AX的影响，然后设计出更健康的面包。该项目的最后阶段将是对这些面包进行人体试验，这将使我们能够验证我们的方法。因此，结果将是(i)了解使白面包更健康的一些方法，以及（ii）一个经过验证的消化模型，以及（iii）了解AX在膳食纤维中的作用。这种理解可以用于健康声明的验证以及新谷物，工艺和产品的开发，模型消化系统将帮助食品工业以更具成本效益的方式探索新的更健康的食品配方。

Wheat is the major food crop grown in the UK. A substantial proportion is used for human consumption, making it an important source of calories, protein, minerals, vitamins and dietary fibre in the human diet. Consumption of fibre is linked to decreased risk of cardiovascular diseases, certain types of cancer, (such as colon and breast) and type-2-diabetes. Cereal-based foods, in particular bread, are a staple in the UK diet and represent one of the major sources of carbohydrate. Whilst there have been drives to increase consumption of wholegrain and wholemeal products, many consumers still prefer the texture and appearance of white bread. Manufacturers are addressing this through processing, using novel fibre-derived ingredients and white wheats to give breads supplemented with bran the appearance of white loaves. However, the value of doing this nutritionally has yet to be demonstrated for each product. White bread is an important UK foodstuff, but being a starchy food which is rapidly broken down to glucose it has a high glycaemic index (GI). Wholemeal bread contains a higher level of dietary fibre, which is considered to be healthier, but forms only a small fraction of the bread eaten in the UK. Dietary fibre contains two components; soluble and insoluble, with the major soluble component in wheat being a fraction known as arabinoxylans (AX), which make up ~70% of wheat endosperm cell wall polymers. The mechanism by which fibre acts is not clear - although there is evidence that its effect is to change the viscosity of the material in the stomach and gut, slowing absorption of nutrient into the body. The aim of this grant is to identify the mechanism for the effect of fibre by studying the effect of changing AX strucutre and solubility. We will first grow (at Rothamsted) four wheats lines which have been shown in previous Rothamsted and IFR collaborative work to have very different AX contents. These will be milled into flour and made into loaves using standard methods at Campden BRI, the UK centre for baking. Grains, flour and breads will be studied to find out what happens to the AX during the breadmaking process, using novel methods developed at IFR and Rothamsted. In addition, we will develop and unify existing equipment at IFR and Birmingham; a model stomach at IFR and a model gut at Birmingham, into a form where it can be used to simulate gastric and duodenal digestion, and study how the cell wall components behave through simulated digestion processes. Using these methods we will be able to identify and explain the effects of AX, and then design breads which have a healthier human response. The final stage of the project will be a human trial of these breads which will allow us to validate our approach. Outcomes will thus be (i) understanding of some of the ways to make white bread more healthy, as well as (ii) a validated model for digestion, and (iii) understanding the role of AX in dietary fibre. This understanding can be used in the validation of health claims as well as in the developments of new grains, processes and products and the model digestion systems will help the food industry to explore new healthier food formulaitons in a more cost-effective manner.