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.

研究概述：本研究开发了四款无麸质面包（gluten-free bread）配方，均添加了可溶性膳食纤维（soluble dietary fiber）与不溶性膳食纤维（insoluble dietary fiber）。对面包的物理特性、化学成分、消费者接受度及购买意愿开展了评价。1号标准样品的配料包括大米粉、木薯淀粉、鸡蛋、乳粉、葵花籽油、食盐、白砂糖、干酵母与饮用水。其余三款样品中，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。仅2号面包的外皮（crust）颜色与1号标准样品存在差异，其红黄色调相较于1号更浅。添加米糠可使3号与4号面包的外皮及内部组织（面包瓤，crumb）颜色更深，红黄色调更显著。相较于其余样品，仅2号面包出现重量损失且成品率更低，推测原因是面团结构在发酵阶段无法维持，发生塌陷。添加菊粉的面包成本更高，因菊粉是公认的益生元（prebiotic）原料，需通过医药渠道采购；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。化学成分层面，3号与4号面包的灰分、蛋白质及膳食纤维含量均有所提升，尤以不溶性膳食纤维为甚；而2号面包的蛋白质含量更低，膳食纤维含量更高，尤以可溶性膳食纤维为甚。从营养学视角而言，此类面包在可消化碳水化合物相关营养及热量价值上均实现了提升。感官评价层面，3号与4号面包在颜色与风味属性上的接受度更低，但在气味与质构（texture）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，采用部分替代淀粉工艺制备的无麸质面包可兼具食品功能特性、营养特性与感官特性，尤其适用于乳糜泻（celiac disease）患者。