超微粉碎后粒径对大麦全粉品质特性的影响

本研究主要以大麦为主要原料,探究不同粒径对超微粉碎大麦粉品质特性的影响.研究结果表明,随着粒径的降低,大麦全粉水分、淀粉含量、溶解性、亮度值及白度值显著增加(P<0.05),而膨润力、吸油性、持水性、峰值黏度和回生值则显著降低(P<0.05).微观结构结果表明,随着粒径的降低,大麦全粉粉体的颗粒形状由圆形或椭圆形转为不...     

Some factors affecting sieving performance and efficiency

Sieving or screening has been the oldest yet most important unit operation for industrial separation of solid particles or as a laboratory method in size analysis. A stack of sieves with decreasing mesh size is usually used. Alternatively, particles can be sifted in a fine to coarse order by multiple sieving steps with each step using a single sieve. The latter is referred to as reverse sieve method. This study compared the two methods for sieving performance and efficiency using flours made from soft white and hard white wheat, hulless barley and medium grain rice. Additional factors, including milling method (impact vs. abrasive), flour moisture (7% vs. 11%), duration of sieving (60 vs. 120 min), and tapping (percussion during sieving), were also investigated. Mass frequency and protein content of oversize fractions were measured. Results show that all the variables and their interactions had significant effects on sieving performance and efficiency. Among them, tapping was most important, followed by sieving duration, sieving method, milling method, flour type, and flour moisture. When other conditions were equal, the reverse sieve method always gave improved sieving efficiency over the stacked sieve method. The observation can be attributed to the beneficial effect of oversized particles on reducing sieve blinding by near or sub-sieve sized particles. Furthermore, the reverse sieve method also expanded the difference in protein content among sieved fractions. Because of its practical significance, this so far unreported effect would bear further confirmation of other sieving and screening conditions.     

Phenolic Acids and Antioxidant Capacity of Distillers Dried Grains with Solubles (DDGS) as Compared with Corn

Three sets of ground corn and the corresponding distillers dried grains with solubles (DDGS) were collected from three commercial plants and analyzed for individual phenolic acids and antioxidant capacity. This study was undertaken to investigate the influence of processing on phenolic acids content and antioxidant capacity of corn and the corresponding processed DDGS samples. The five phenolic acids identified in corn and DDGS were vanillic, caffeic, p-coumaric, ferulic, and sinapic acids. Ferulic and p-coumaric acids accounted for about 80% of the total identified and quantified phenolic acids. The phenolic acids profile of DDGS was comparable to that of corn. The content of total phenolic acids per gram basis, in DDGS was 3.40 fold higher and antioxidant capacity was 2.58 fold more than that of corn. These observations suggest that there was little degradation in individual phenolic acids content during dry grind processing. Furthermore, significant variation in measured individual and total phenolic acids, and antioxidant capacity among processing plants existed for both corn and DDGS. Results from this study will be valuable to bioethanol manufacturers and the feed industry.