Inclusion of dietary fiber in gluten-free breads

Summary Four gluten-free bread formulations were developed, with the inclusion of soluble and insoluble dietary fiber. Physical properties, chemical composition, acceptance and purchase intent of consumers were evaluated. The standard sample (1) had rice flour, cassava starch, egg, powdered milk, sunflower oil, salt, sugar, dry yeast and water as ingredients. In the other samples, the starch was partially replaced by inulin (2), defatted rice bran and inulin (3), and defatted rice bran (4). The color of bread 2 differed only in the crust, which was less red and yellow than standard sample (1). The inclusion of rice bran yielded a darker, red and yellow color to the crust and the crumb of the breads 3 and 4. Only bread 2 had loss of weight and lower yield, compared to the other samples, probably due to the dough structure collapse, which was not sustained at the growth stage. The cost of the breads with inulin was greater, for this is a well known prebiotic ingredient, acquired in pharmaceutical establishments; whereas the cost of bread with bran decreased, since it is an industrial by-product obtained from the extraction of rice oil. Regarding chemical composition, there was an increase in ash, protein and dietary fiber contents, especially insoluble, in breads 3 and 4; whereas bread 2 had lower protein and higher dietary fiber content, especially soluble. Nutritionally, an increase in the nutritional value over digestible carbohydrates and caloric value is accepted. Sensorily, breads 3 and 4 were less preferred regarding color and flavor attributes, but did not differ from breads 1 and 2 in odor and texture attributes, and consumers purchase intent. It was concluded that the consumption of breads with partial replacement of starch ensures food functional quality, nutritional and sensorial, especially in the celiac case.

研究摘要：本研究开发了四种无麸质面包（gluten-free bread）配方，均添加了可溶性膳食纤维与不溶性膳食纤维（soluble and insoluble dietary fiber）。研究对面包的物理特性、化学成分、消费者接受度与购买意愿进行了系统评价。标准样品（1号）的配料包括米粉、木薯淀粉、鸡蛋、奶粉、葵花籽油、食盐、白砂糖、干酵母与水。其余样品中，淀粉分别被菊粉（inulin）（2号）、脱脂米糠（defatted rice bran）与菊粉（3号）、脱脂米糠（4号）部分替代。面包2仅表皮颜色存在差异，其表皮的红度与黄度均低于标准样品1号。添加米糠的3号与4号面包，其表皮与面包瓤（crumb）的颜色更深，红度与黄度更高。相较于其余样品，仅面包2出现重量损失且出品率更低，这可能是由于面团结构在发酵阶段无法维持而坍塌所致。添加菊粉的面包成本更高，因菊粉是已知的益生元（prebiotic）成分，需从医药机构采购；而添加米糠的面包成本更低，因米糠是稻米油提取过程中产生的工业副产物。化学成分方面，3号与4号面包的灰分（ash）、蛋白质与膳食纤维（尤其是不溶性膳食纤维）含量均有所提升；而2号面包的蛋白质含量更低，膳食纤维（尤其是可溶性膳食纤维）含量更高。营养学层面，可消化碳水化合物与热量值的提升可有效增益面包的营养价值，这一点已获公认。感官评价结果显示，3号与4号面包在颜色与风味属性上的接受度更低，但在气味与质地属性上与1号、2号面包无显著差异，消费者购买意愿也无明显区别。综上，通过部分替代淀粉制备的面包可兼具功能特性、营养与感官品质，尤其适用于乳糜泻（celiac disease）患者。