On Predicting Roller Milling Performance IV: Effect of Roll Disposition on the Particle Size Distribution from First Break Milling of Wheat

Abstract

The breakage equation for roller milling allows prediction of the output particle size distribution from the feed particle size distribution in terms of a breakage function. Breakage functions were determined for First Break milling of hard and soft wheats under four roll dispositions: Sharp-to-Sharp (S-S), Sharp-to-Dull (S-D), Dull-to-Sharp (D-S) and Dull-to-Dull (D-D). The breakage functions were then used to predict the particle size distribution resulting from milling whole wheat samples at different roll gaps, for comparison with experimental results. First Break milling of both hard and soft wheat samples under a S-S disposition gave an even distribution of particle sizes over the range 250±2000 mm, which could be described by linear breakage functions. The effect of changing roll gap was to change the slope of the line i.e. to change the balance between small and large particles, with larger roll gaps giving a greater proportion of large panicles. Milling under S-D, D-S and D-D dispositions gave progressively more`Ushaped' distributions; these were described by quadratic functions that indicated large quantities of small and large particles, but fewer in the middle size range. Again, increasing roll gap changed the balance towards more large particles, but had little effect on the quantity of particles in the middle size range. Predictions of output cumulative particle size distributions using the breakage equation gave excellent agreement with independently derived experimental results, with R 2 in excess of 0Á99 in all cases. The trend in wheat quality testing is to measure distributions of single kernel parameters. The breakage equation approach allows the link to be made between distributions of single kernel parameters and milling performance.

Dry processing of oats – Application of dry milling

“…flour extraction rate (material <212 lm) and a corresponding increase in proportion of material larger than 2000 lm. This is as expected, as less breakage occurs at larger roll gaps, although the linear relationships are in contrast with the quadratic relationships observed for wheat milling (Campbell, Bunn, Webb, & Hook, 2001;Fang & Campbell, 2003). Milling at a roll gap of 0.1 mm released more than 18% flour, while maintaining 32.6% of the starting material as particles larger than 2000 lm.…”

“…The effects of roller milling parameters on oat breakage were investigated using the versatile Satake STR-100 test roller mill (Satake Corporation, Hiroshima, Japan) Fang & Campbell, 2002, 2003, using a feeding rate equivalent to 300 kg h À1 , and fitted with either corrugated or smooth rolls. All rolls were manufactured to industrial configurations for wheat flour milling, having diameters of 250 mm, but only 100 mm in length (compared with 1000 mm typically for industrial roller mills).…”

Effects of kernel hardness and moisture content on wheat breakage in the single kernel characterisation system

“…The cumulative percentage of undersize particles was also respectively, while x , just beyond the particle size 75 range measured, was estimated to be 3434 mm. These particle sizes are much larger than would be expected from First Break roller milling, for which the x is 50 typically in the range 500-1500 mm (Fang & Campbell, 2003a). This suggests that the mechanism of breakage in the SKCS is primarily compression, which tends to produce larger particles, in contrast to roller milling in which shear contributes significantly, as well as compression, the relative contributions depending on roll disposition (Fang & Campbell, 2002a,b, 2003a.…”

Specific median flour particle size distribution of Japanese common wheats; comparison with Chinese common wheats

“…Flour particle size distribution is an important indicator of the quality of high-ratio flour (Posner and Hibbs 1997), and commercial wheat flour samples are often characterized according to their particle size properties (Gaines 1985;McDonald 1994). It would therefore be useful to determine the relationship between flour yield and flour particle size distribution (Wu et al 1990;Fang and Campbell 2003;Kim et al 2004) and, revealed the effect of median flour particle size (µm) in wheat flour yield, so that the median flour particle size could be used as an index of flour yield in Japanese wheat breed programs, and developed a suitable method to evaluate flour yield of Japanese wheat (Nakamura 2014). Therefore, the aims of the current study are to investigate the differences of a median flour particle size between Japanese and Chinese common wheats, and could simply and quickly identify wheat genetic resources with high flour yielding in a systematic evaluation of N.A.R.O.…”