A Device for the Preparation of Cereal Endosperm Bricks

Abstract

sp. L.) endosperm hardness (kernel texture) has been a topic of intense interest for the past ≈100 years (Pomeranz and Williams 1990; Morris 2002). One of the first recorded devices for measuring wheat kernel texture was that of Roberts (1910), which determined the force required to crush individual kernels. There are two reasons why the assessment of kernel texture in wheat, in particular, is of great interest: 1) wheat exhibits distinct classes of kernel texture, namely soft, hard, and durum; and 2) the differences in kernel texture among these classes has a profound effect on flour milling, starch damage, particle size distribution, water absorption, and end-use quality (Morris and Rose 1996; Morris 2002). As we will describe, our objective was to produce a geometrically defined subsample of the endosperm as opposed to studying the whole kernel. The measurement of wheat kernel texture has been largely empirical because kernels and endosperm are difficult to work with due largely to their diminutive size. Current methods (AACC International 2000) such as near-infrared reflectance (Approved Method 39-70A), particle size index (Approved Method 55-30), and single kernel characterization System (Approved Method 55-31) provide measurements in arbitrary unitless proportions or scales. Generally, to obtain objective measures of material proper-ties in universal units of force, work, etc., complex geometries must be simplified, and in the case of wheat, the bran, germ, and pigment strand should also be eliminated. A few researchers have been successful in achieving this goal. Glenn of the USDA devel-oped a method of “turning” on a lathe endosperm cylinders of defined geometry, and then subjecting them to testing in both com-pression and tension (Glenn et al 1991; Jolly 1991; Jolly et al 1996; Delwiche 2000; Osborne et al 2001; Dobraszczyk et al 2002). This same technique was studied in the senior author’s lab and found to be exceedingly tedious. The centering of the kernel “cheek” on the lathe stub was particularly problematic. Haddad, Abecassis and co-workers (Haddad et al 1998, 1999, 2001; Sam-son et al 2005) eliminated the problems associated with “turning” cylinders, by preparing through sanding rectangular parallelepi-pedal test samples. Here we term such specimens “bricks”. We have devised and constructed a similar device that eliminates the need for adhesive paper and glue to hold specimens during their preparation (see Haddad et al 1998). Furthermore, one of the pro-cessing steps in the technique described by Haddad et al (1998) as “Two machined half-grains are placed between two sheets, and a wedge is set at height l of the extremities of the sheets” has been eliminated. We have used the device described here to prepare hundreds of bricks of various wheat (