Barley for Food and Health: Science, Technology, and Products

WHOLE-GRAIN PROCESSING 111
contained high levels of β-glucan and an intermediate level of arabinoxylan,
whereas bran exhibited the opposite ratio of β-glucan and arabinoxylan, which
is representative of the outer layers of the kernel.
Andersson et al. (2003) presented data on the tocol content of the milling
fractions. The tocol levels in the whole barleys are shown in Table 4.4. Analyses
of the milling fractions showed the highest levels of each of the eight tocol
isomers in bran, intermediate in shorts, and least in flour. Tocotrienols (T3) were
significantly higher than tocopherols (T) in each milling fraction. Totals of T3
and T (mg/kg) in flour, shorts, and bran were 9.6, 6.0; 45.3, 13.1; and 55.7, 14.0,
respectively. The ratios of T3 to T in flour, bran, and shorts were 1.6 : 1, 3.5 : 1,
and 4.0 : 1, respectively.
Other research centers have evaluated the nutritional and functional characteristics
of hulless barley. Ames et al. (2006) milled 10 hulless barley genotypes
in a Bühler mill producing straight-grade flour, shorts, and bran. Composition of
the straight-grade flour and shorts and bran fractions exhibited wide genotypic
variation. Seven of the genotypes had straight-grade flours with low levels of
β-glucan (6.5% β-glucan, >18%
dietary fiber, and less than 60% starch. The shorts and bran fractions of all genotypes
contained higher concentrations of β-glucan and total dietary fiber than
those of the straight-grade flour. The shorts and bran fractions from the two
genotypes with the high levels of β-glucan and dietary fiber were also higher in
these components than in comparable fractions from the other genotypes.
Barley β-glucans present major problems to overcome if barley is to be
roller-milled successfully to produce straight-grade flour. Starch type also presents
challenges, as in addition to having different granule sizes, the waxy and highamylose
types also contain higher-than-normal levels of β-glucans. Shorts and
bran fractions offer possibilities of use to enhance the nutritional components
in certain types of baked goods, such as cookies, muffins, cakes, and specialty
breads. Major improvements in roller-milling techniques have been made to produce
flour from barley that can be used in a multitude of food products.
Malting
Barley has been malted, or germinated, prior to consumption for thousands of
years. It has been documented that any barley having a sound, viable kernel will
produce malt, but quality factors would be sacrificed in most cases. Commercial
malt is defined as a modified kernel from which the dried rootlets and sprouts
have been separated and removed. In modern malting operations, strict criteria
are observed in the selection of barley for malting, not the least of which are the
desires and wishes of the brewery, distillery, and/or the brewmaster. A number
of major considerations paramount in the choice of a barley for malting include
genotypes, kernel size, soundness, color, brightness, a germinating capacity of ≥
96%, relatively low protein (≤12.0%), and the absence of insect, microbial, heat,
and weather damage. Observations on the rate of modification of various barleys