麦麸酚基木聚糖对发酵面团特性和馒头品质的影响

为了提高麦麸的附加值、馒头的品质以及增强馒头的营养价值,该试验以小麦粉为原料,采用2个分子量的麦麸酚基木聚糖（820、581 kD）,研究不同添加量（0.25%、0.5%、1.0%、2.0%）对发酵面团特性以及馒头品质的影响。结果表明：随着麦麸酚基木聚糖添加量的增加,发酵面团的弹性模量、质子密度A22先增加后下降,黏性模量、质子密度A23增加,弛豫时间T22下降;馒头的亮度下降,红度和黄度增加,比容、黏聚性、回复性先增加后下降,硬度、咀嚼性先下降后上升,黏附性下降,馒头的感官得分先上升后下降。高分子量的麦麸酚基木聚糖,其发酵面团的弹性模量和黏性模量变幅较大,弛豫时间T22、T23较大、质子密度A21较小,低分子量的麦麸酚基木聚糖,其馒头比容和弹性较大,但馒头硬度和咀嚼性相对也较大。麦麸酚基木聚糖添加量在0.5%时,对发酵面团以及馒头品质改善效果最好。添加量在1.0%内,发酵面团特性以及馒头品质均可接受。高分子量的酚基木聚糖对发酵面团以及馒头品质改善效果高于低分子量的酚基木聚糖。研究结果为麦麸酚基木聚糖广泛应用于馒头中,提高馒头品质及营养价值提供理论依据。

Effects of phenolic xylans from wheat bran on fermented dough properties and qualities of steamed bread

Abstract: In order to develop a natural, safe improver of steamed bread and nutrition fortifier, as well as increase the added value of wheat bran, phenolic xylans from wheat bran with different addition level (0.25%, 0.5%, 1.0%, 2.0%) and molecular weight (82°, 581kD) were chosen and their effects on fermented dough properties and qualities of steamed bread were investigated. Low molecular weight phenolic xylans were obtained by ultrasonic degradation of phenolic xylans. The rheometer and low-field nuclear resonance (NMR) were used to observe the changes of fermented dough properties with phenolic xylans. The texture profile analyzer was used to observe the changes of qualities of steamed bread with phenolic xylans. The viscoelasticity, water distribution and mobility of fermented dough, color, texture, sensory evaluation score of steamed bread were evaluated in the experiment. The results showed that along with the increase of phenolic xylans from wheat bran, the elastic modulus and proton density A22 increased then decreased, viscous modulus and proton density A23 increased, relaxation time T22 of fermented dough decreased. The lightness and adhesiveness decreased, redness and yellowness increased, specific volume, cohesiveness, resilience and sensory score of steamed bread increased and then decreased, hardness and chewiness of steamed bread decreased and then increased with increasing addition level of phenolic xylans from wheat bran. The higher molecular weight of wheat bran phenolic xylans was, the larger quantitative change of the elastic modulus and viscous modulus would be. The high molecular weight wheat bran phenolic xylans had long relaxation time T22 and small proton density A21 of fermented dough. When the molecular weight of wheat bran phenolic xylans was low, the specific volume and springiness of steamed bread were large, but the hardness and chewiness of steamed bread were relatively large. Compared with the control group, the addition of phenolic xylans from wheat bran could improve the rheological properties and water properties of fermented dough and quality of steamed bread. When the content of wheat bran phenolic xylans was 0.5%, the improvement effect of fermented dough and steamed bread qualities was best. When the addition level of wheat bran phenolic xylans was lower than 1.0%, the properties of fermented dough and qualities of steamed bread were improved. However, the properties of fermented dough and qualities of steamed bread deteriorated when phenolic xylans content was 2.0%. The improvement effect of properties of fermented dough and qualities of steamed bread with high molecular weight wheat bran phenolic xylans was better than low molecular weight wheat bran phenolic xylans. The method and data stated in this study were useful and valuable to the industry and can provide the theoretical basis for phenolic xylans widely application to the flour products.