Prediction of Breakage During Roller Milling of Wheat Kernels, Based on Single Kernel Measurements

Abstract

Pengilangan tepung gandum melibatkan pengisaran bijirin secara berulang-kali (menggunakan roller mill) dan pemisahan (secara pengayakan) bagi perolehan semula hasilan tepung yang berkesan yang secara bandingannya bersih dari pencemaran bran. Satu permulaan bagi membina model perlakuan terhadap campuran bijirin gandum ialah keupayaan bagi menentu-ukur kelainan ciri-ciri yang wujud dalam campuran tersebut. Alatan Perten Single Kernel Characterisation System (SKCS) dapat memberikan taburan kuantitatif bagi jisim, kandungan lembapan, garis pusat dan nilai kekerasan bagi campuran bijirin tersebut, berdasarkan pengukuran 300 kernel dalam masa 5 minit. Cabarannya ialah menghubungkaitkan taburan yang telah ditentukur kepada ramalan keupayaan pengilangan. Pada tahap ini, satu bentuk kefungsian pengisaran (breakage function) dalam konteks parameter tentu-ukuran bagi setiap kernel bijirin telah diterbitkan, dan diintegrasi kepada taburan sifat kernel menggunakan persamaan proses pengisaran (breakage equation). Dengan menggunakan model tersebut, satu jangkaan boleh dilakukan ke atas taburan saiz partikel hasil keluaran pengisaran siri pertama atau First Break roller milling bagi kernel bijirin yang berbeza saiz, kekerasan dan kelainannya, berdasarkan hanya pada ciri-ciri taburan yang diberikan oleh SKCS. Model tersebut telah diuji ke atas hasil keluaran pengisaran pada disposisi (roll disposition) pengisaran sharp-to-sharp dan dull-to-dull, dan didapati menunjukkan keseragaman dengan data bebas (independent data). Kata kunci: Tingkah laku pengisaran, taburan saiz partikel, pemecahan, pengujian satu–kernel, bijirin Wheat flour milling involves repeated breakage (by roller milling) and separation (by sifting) of flour particles to give efficient recovery of fine flour relatively free from bran contamination. A starting point for modelling the behaviour of mixtures of wheat kernels is to be able to measure the variation in kernel properties within the mixture. The Perten Single Kernel Characterisation System (SKCS) gives the distributions of kernel mass, moisture content, diameter and hardness within a mixture, from 300 kernels within 5 minutes. A challenge remains to relate these measured distributions to predictions of milling performance. To this end, a breakage function in terms of these measured parameters for individual kernels has been constructed, and integrated over the distribution of kernel properties using the breakage equation. These models allow prediction of the output particle size distribution delivered by First Break roller milling of kernels varying in size, hardness and variety, based entirely on SKCS characteristics. Predictions have been developed for both sharp-to-sharp and dull-to-dull roll dispositions, and show encouraging agreement with independent data. Key words: Milling behaviour, particle size distribution, breakage, single kernel testing, wheat

Influence of wheat kernel physical properties on the pulverizing process

“…Beside of this the SKCS measures the weight, diameter, and moisture of (usually) 300 individual kernels within 5 min, and provides information in the form of means and distributions (Muhamad and Campbell 2004). The numerous workers have applied the SKCS to a range of studies and have concluded that it gives useful results, especially for prediction wheat milling performance (Osborne et al 1997;Muhamad et al 2008). However there are no studies concerning the relation between SKCS parameters and impact grinding results, especially in relation to wholemeal flour production.…”