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

102 BARLEY PROCESSING: METHODS AND PRODUCT COMPOSITION
higher levels of tocopherol (132.6 mg/kg) and tocotrienol (224.8 mg/kg). The different
findings between the two studies may in part be explained by differences in
analytical techniques, barley cultivars, and method of sample preparation. In the
study reported by Wang et al. (1993), the pearlings were produced with a model
6K572 laboratory-type barley pearler (Dayton Electric Manufacturing, Chicago,
Illinois), whereas Moreau (2007) used a laboratory seed scarifier (Forsberg, Thief
River Falls, Minnesota). Phytosterols as well as the vitamin E components have
been shown to have positive health benefits. Lampi et al. (2004) reported that
pearling fines of hulless barley contained about 2 mg/g phytosterol compounds,
which was at least double that in the whole grain. In addition to the evaluation of
barley pearlings for tocols, Moreau et al. (2007) examined the phytosterol contents.
They reported an average of 2.35 mg/g total phytosterols in the pearlings,
a 209% increase over the level in the whole barley grain.
Commercially pearled barley usually represents approximately 60 to 70% of
the original barley kernel and is the typical product used for soups and pilafs. It is
also the material for further processing, including grinding, flaking, cutting, and
roller milling. Blocked and pearled barley may be used for soups, stews, pilafs,
and other dishes and also as a rice extender, as noted without further processing.
Pearled barley may be lightly cooked or roasted through various processes to
produce “quick-cooking” barley products. Pearling fractions can be produced
utilizing various extraction rates that vary widely in their physical, chemical, and
functional characteristics. Thus, the various layers removed as by-products in the
pearling process can be utilized in formulating numerous end products, especially
for the production of functional foods with defined health benefits. When used as
a rice extender, pearled barley adds β-glucans and increases the SDF significantly
in recipes with rice.
Most experimental studies of pearling barley generally used laboratory-scale
pearling machines such as that from Seedburo Equipment Co., Chicago, Illinois or
Satake, Tokyo, Japan. The laboratory equipment used in research produces pearl
barley and pearlings that are comparable to those produced by large commercial
pearling equipment, as evidenced by the similar findings reported by Marconi
et al. (2000), thereby negating the need for large quantities of barley for initial
evaluations.
Grinding
Grinding of cereal grains in the broad sense can range from simple abrasion,
producing whole-meal flour in a stone mill, to a complex mechanical system
utilizing various methods for separation and regrinding. Grinding is a form of
dry milling for the production of whole-grain flour or meal that may be used
as received from the grinder or separated into fractions having different particle
size and/or density using air classification and/or sieving techniques.
Stone mills developed by the Romans in the second century b.c. wereusedfor
over 1000 years in Europe to grind barley into whole meal and flour. A typical
stone mill consists of at least two abrasive stone disks positioned on a vertical