Effects of Grinding Strength on Physicochemical Properties and Protein Extraction of Rapeseed Meal Powder

In order to explore the effects of grinding strength on the physicochemical properties and protein extraction of rapeseed meal powder, cryogenic superfine milling was used to prepare six kinds of rapeseed meal powders according to the grinding time (5, 10, 15, 20, 30, 40, and 60 min), namely SGR-5, SGR-10, SGR-15, SGR-20, SGR-30, SG-40, SG-60, and conventional crushing one was used as a control, named GR. The results showed that the structure of the rapeseed meal was easily destroyed by a moderate superfine grinding compared with the conventional crushing, which was followed by a reduction in their particle size distribution, insoluble fiber content, and water/oil holding capacity, thereby increasing the protein extraction rate. While the grinding process had almost no effect on their total fiber content. Specially, a minimum particle size of the powder would be gotten when grinding for 40 min, about 16 μm (D₅₀), and further grinding would cause the aggregation of powder particles. Moreover, 30 min of superfine grinding was the optimal condition for the extraction of rapeseed meal protein by alkali-extraction. In addition, the alkali pH was another important parameter for the extraction of rapeseed protein.