VTT Technical Research Centre of Finland, Ltd., P.O. Box 1000, FI-02044 VTT, Finland.
Food Res Int. 2021 Jan;139:109971. doi: 10.1016/j.foodres.2020.109971. Epub 2020 Dec 8.
Dry milling and air classification were applied to produce three different ingredients from wheat and rye brans. Dried and pin disc-milled brans having particle size medians of 89-131 µm were air classified to produce protein- and soluble dietary fibre-enriched hybrid ingredients (median particle size 7-9 µm) and additionally brans were ultra-finely milled (median particle size 17-19 µm). The samples were characterised in regard to their composition and techno-functional properties. In air classification, protein content increased from 16.4 and 14.7% to 30.9 and 30.7% for wheat and rye brans, which corresponded to protein separation efficiencies of 18.0 and 26.9%, respectively. Concurrently, the ratio between soluble and insoluble dietary fibre increased from 0.22 to 0.85 for wheat and from 0.56 to 1.75 for rye bran. The protein- and soluble dietary fibre-enriched wheat bran fraction showed improved protein solubility at alkaline pH when compared to pin disc- and ultra-finely-milled wheat bran, whereas less difference between the wheat ingredients was observed at native and acidic pH. The protein- and soluble dietary fibre-enriched rye bran fraction exhibited lower solubility than the pin disc- or ultra-finely-milled rye brans at all the studied pH-values. Ultra-fine milling alone decreased protein solubility and increased damaged starch content when compared to the pin disc-milled brans. Both protein enrichment and ultra-fine milling improved colloidal stability in comparison to the pin disc-milled raw materials. The lowest water and oil binding capacities were obtained for the protein-enriched fractions. Ultrasound-assisted emulsification of the protein- and soluble dietary fibre-enriched fractions and the ultra-finely-milled brans revealed no major differences in the visual quality or stability of the emulsions. The results suggest that modification of the techno-functional properties of cereal brans may be acquired via both air classification and ultra-fine milling.
干法粉碎和空气分级被应用于从小麦和黑麦麸皮中生产三种不同的成分。将干燥并通过圆盘磨粉碎至粒径中值为 89-131 µm 的麸皮进行空气分级，以生产富含蛋白质和可溶性膳食纤维的混合成分（粒径中值为 7-9 µm），此外还可以将麸皮进行超微粉碎（粒径中值为 17-19 µm）。对这些样品进行了组成和工艺功能特性方面的表征。在空气分级过程中，蛋白质含量从 16.4%和 14.7%分别增加到 30.9%和 30.7%，这对应于蛋白质分离效率分别为 18.0%和 26.9%。同时，可溶性膳食纤维与不溶性膳食纤维的比例从 0.22 增加到 0.85，小麦麸皮从 0.56 增加到 1.75，黑麦麸皮。与圆盘磨和超微粉碎的小麦麸皮相比，富含蛋白质和可溶性膳食纤维的小麦麸皮部分在碱性 pH 下具有改善的蛋白质溶解度，而在天然和酸性 pH 下，小麦成分之间的差异较小。与圆盘磨或超微粉碎的黑麦麸皮相比，富含蛋白质和可溶性膳食纤维的黑麦麸皮部分在所有研究的 pH 值下的溶解度都较低。与圆盘磨粉碎的麸皮相比，单独进行超微粉碎会降低蛋白质溶解度并增加受损淀粉含量。与圆盘磨粉碎的原料相比，蛋白质富集和超微粉碎均提高了胶体稳定性。蛋白质富集部分的水和油结合能力最低。对富含蛋白质和可溶性膳食纤维的部分以及超微粉碎的麸皮进行超声辅助乳化，发现乳液的外观质量和稳定性没有明显差异。结果表明，通过空气分级和超微粉碎可以获得谷物麸皮的工艺功能特性的改性。
