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VII. Requirements of Malting Barley
MALTING BARLEY I N THE UNITED STATES
may represent an improvement in the malting quality of the barley. However, these changes are accepted rather reluctantly, if at all, by industry
because modification of their operation may result in a slightly different
end product or affect the economics of production. Thus, specifications
for malt often include the amounts of the barley varieties desired as the
raw material, along with standards for other properties.
Certain factors are used to evaluate malting quality. Some of these
factors can be determined ,from the barley grain while others are evaluated
on the malt. Anderson et al. (1943) gave an excellent discussion of malting quality characteristics for Canadian barleys. A report from the Brewing
and Malting Barley Research Institute, Winnipeg, Manitoba, in 1967, defined the standards for many of the malting quality properties. Specific
standards for malting quality factors desired by the United States industry
have not been published, but the general requirements have been discussed
by Dickson and Burkhart (1956), Sfat (1963), Olson (1963), Rosenbusch (1966), Hunt ( 1968), and Seidl ( 1972). Various committees involving industry, state, and federal personnel have attempted to establish
desirable ranges for the measured quality factors. Eflbrts coordinated by
the Malting Barley Improvement Association, Milwaukee, Wisconsin, are
continuing toward this objective.
Grain buyers at the local market and malting barley merchandisers at
the terminal grain markets use characteristics of the barley grain to determine price and quality premiums. Barley variety, protein content, kernel
plumpness, and kernel discoloration are the major factors involved. Other
values established through assignment of the official grade of barley provide supplemental information for the malting barley merchandisers and
the maltsters purchasing barley.
General requirements of desirable malting barley as defined by industry
representatives will be discussed. Major emphasis will be devoted to standards for midwestern grown six-rowed barley used for brewer's malt because this represents over three-fourths of the total malt production in the
A list of acceptable malting barley varieties is established as a result
of collaborative quality testing programs of Agricultural Experiment Stations from malting barley-producing states with industry, represented by
the Malting Barley Improvement Associaton, Milwaukee, Wisconsin. Varieties show distinct differences in the way they react during malting and
brewing and acceptable varieties can be processed more efficiently. Carload
lots of a single variety are desired by industry, which provides a raw mate-
0. A. PETERSON AND A. E. FOSTER
rial of known genetic performance within a range of environmental variability. Processing a known variety by the maltster is less difficult than
processing a mixture and allows blending of different finished malts to meet
specifications of malt users.
Kernel size of malting barley is defined by two different agencies.
Country elevators and malting barley buyers in areas of production or major terminal markets near production areas define “percent plump” barley
as those barley kernels staying on top of a sieve having slotted perforations
of 8/04 inch by 5/4 inch. Official grain standards of the Consumer and Marketing Service, Grain Division, USDA, define “percent thin” barley in the
class Barley as “barley and other matter that will pass readily through a
744 )( 5/4 (inch, slotted perforations) sieve” and “percent thin” in the
class Western Barley shall be “barley and other matter that will pass readily through a 51/,/64 X % (inch, slotted perforations) sieve.” “Thin
barley” is determined after the removal of dockage in official grading by the
Licensed Inspector. Probably “plump barley” also is determined after the
removal of dockage in the country elevator or before the malting barley
buyer applies a plump percentage in the central or terminal market. Thin
barley and other matter that passes through a %j4 X % inch sieve is not
used for brewers malt and represents an economic loss. Uniformity in kernel size, obtained through use of seives, and in kernel shape through handling of single variety lots, is important for uniform steeping, germination,
and grinding in the malt mill.
Test weight is used to determine the suitability of barley for malting
as an approximate indicator of malt extract potential. Although test weight
has some merit as a measure of extract potential, it is less accurate than
kernel plumpness. Test weight can be influenced greatly by closeness of
threshing with higher values obtained by skinning or hull removal.
Skinned kernels are those in which one-third of the lemma or palea is
removed, or which have the lemma loosened or removed over the embryo.
A broken kernel of barley is one that is broken regardless of the extent
or size of the pieces. The official grain standards of the United States allow
a maximum of 8% skinned and/or broken kernels within the subclasses
for six-rowed malting barley and 10% within the special grades of tworowed malting barley. A lower level of skinned kernels is preferred since
the hull (lemma and palea) helps regulate water and oxygen absorption
MALTING BARLEY I N THE UNITED STATES
and prevents mechanical injury of the coleoptile during the malting process. Greater uniformity of germination among the kernels and a more
complete modification of the barley to malt is experienced with nonskinned
kernels. Also, the brewer uses the hull as a filter aid in the brewing process so that a low hull percentage may give an undesirable separation of
the solubilized wort. Broken kernels which cannot be removed in the cleaning process will reduce the quality of the malt because they will seldom
Germination is basic to the malting process. The germination percentage
should be above 95% to assure that the proper chemical and physical
changes occur to produce high quality malt. The vigor and uniformity of
germination among the barley kernels is important in the rate and the
degree to which the changes take place. The percentage and vigor of germination are influenced by the many factors that determine soundness of the
kernel and by post-harvest dormancy.
Since barley usually is stored for at least 3 months prior to malting,
kernel moisture content should be 13% or less. Storage above 13% moisture may result in damage due to the growth of microorganisms on or
within the kernel, or from an increase in temperature within the grain.
These factors may cause loss of viability and of germination vigor, or cause
undesirable chemical changes within the kernel to render the barley unsuitable for malting.
F. SOUND BARLEY
Sound barley refers to whole kernels and pieces of kernels of barley
which are not classified as “damaged.” There are many factors that influence soundness, such as disease, heat, sprouting, frost, ground damage, and
weathering. The standards of the maltster for soundness are higher than
those listed for malting barley in the official grain standards of the United
States. Low tolerances are set by maltsters because most of the damaging
factors reduce germination or cause chemical changes in the kernel which
affect flavor, or color, or cause processing difficulties in products made
OTHER GRAINSAND FOREIGN
The use of barley which is not contaminated with other agricultural crop
seeds, with weed seeds, or with foreign material of any type is the goal
0. A. PETERSON AND A. E. FOSTER
of the maltster. Economic loss as a result of dockage removal or a reduction in the quality of the malt may occur if contaminants cannot be separated from the barley.
Protein content of malting barley is one of the most important considerations because of the effect protein has on the malting and brewing processes as well as on the resultant end products of these processes (Olson,
1963). High kernel protein tends to lengthen the steeping time and causes
uneven germination in the malthouse. Blends of high and low protein barley increase the problem of uneven germination. High protein barley increases malting losses from higher respiration and rootlet losses. Also, high
protein may cause a flinty appearance within the endosperm and as a result, mellowness of the malt is reduced. Protein is necessary for the development of many of the key analytical properties of malt. Excessive levels
of kernel protein in barley decrease the amount of soluble material that
can be extracted from both fine or coarsely ground malt and ultimately
decreases the percent of extractable material. Enzymatic activity, as measured by diastatic power and u-amylase in the malt, and soluble protein
in wort obtained from the filtered extract of malt, increase with the use
of high-protein malting barley. These increases may cause undesirable
changes in the processing and end products of malt.
The malting and brewing industry has defined protein specifications for
barley that meet the standards desired in their raw material, barley. Acceptable upper protein limits for barley on a percent dry basis are 13.5% for
the Midwestern six-rowed type, 13.0% for the Western two-rowed type,
and 11.O% for the Western six-rowed type, which includes the Coast and
Winter Tennessee groups. However, preferred levels for these three types
are 12.5%, 12.0%, and 9.0%, respectively. Protein levels of barley that
is grown in the United States are rarely too low (Olson, 1963).
Soluble protein is that portion of the nitrogenous compounds in malt
which is solubilized in the mashing process. Although determination of
soluble protein is made after malting, the amount of barley protein and
proteolytic activity potential is basic to this factor. Fermentation efficiency, related to yeast metabolism, and amount of soluble protein. in the
finished product of brewing are important factors dependent on the soluble
protein in the wort. Individual brewers specify ranges for soluble protein,
but standards for the industry as a whole have not been established.
MALTING BARLEY IN THE UNITED STATES
The amount of extractable material in barley or malt can be measured.
The requirements for extract have no upper limit since this factor is associated with brewhouse yield. Among the acceptable varieties, the tworowed varieties tend to have higher extract levels than six-rowed types.
The difference between extracts obtained from finely and coarsely ground
malts is used as an indication of the efficiency with which extractable solids
can be recovered in the brewing process and is a measure of the degree
of modification. A barley which can produce a well-modified malt would
have a low fine-coarse extract difference. The fine grind extract measures
the yield potential, but the coarse grind extract relates to the yields obtained in actual brewhouse practice.
One of the main reasons why barley is used more extensively than other
grains for malting is the presence of or ability to develop acceptable levels
of the proper enzymes. The amylases or starch-splitting enzymes are of
major importance since they must act on the starch of the barley endosperm as well as on the adjunct of other grains added in the mashing process during brewing. Diastatic power, determined on barley or malt, and
a-amylase determined on malt, are measures of the activity of these amylolytic enzymes. Industry-wide standards have not been established for diastatic power and a-amylase, but individual companies have specified requirements. Normally, the acceptable enzymatic activity ranges are within
those that can be provided by the widely grown acceptable malting varieties. Specifications for the proteolytic enzymes are not given for barley
or malt but are reflected in the soluble protein or percentage of soluble
protein relative to total protein values. Other enzyme systems are known
to be important in malting barley, but requirements have not been established for conventional commercial malting. As they become better understood with further research, additional enzyme specifications may be added
by the users of malt. One of these may be p-glucanase because of its importance in modification of the kernel during malting.
Sources of Variability in Malting Quality Factors
The sources of variation associated with chemically determined malting
quality factors have not been studied as extensively and are less understood
than agronomic characteristics and most of the physical quality factors of
G . A. PETERSON AND A. E. FOSTER
malting barley. However, studies on varieties (Shellenberger and Bailey,
1936; Anderson et al., 1943; Harris and Banasik, 1952) and experience
by industry (Kneen and Dickson, 1967) have established that both genotype and environment influence the chemical composition of the barley
kernel. The range of values for quality characteristics, such as percentage
of barley or malt protein, extract percentage, and diastatic power of a malting barley variety over environments, usually would be expected to be
greater than for several malting barley varieties grown under one environment. As an example, Anderson (1944) indicated that protein content
of varieties grown under identical conditions rarely differs by more than
1.5 percentage units, but the protein content of the same variety grown
under widely different conditions may vary by as much as 10 percentage
The influence of environment on malting quality of barley has been
categorized as the effects of location and season (Harris and Banasik,
1952; Rasmusson and Glass, 1967). The environmental factors that cause
the greatest amount of variability in malting quality is not consistent among
all studies. Undoubtedly, soil moisture levels, temperatures during the
growing period, and availability of essential nutrients for plant growth are
three of the most important constituents in determining the physical and
chemical properties of malting barley. A relatively universal generalization
exists, that any limitation or deficiency among these constituents which
stress the barley plant growth normally renders the resulting barley grain
less suitable to meet desirable malting barley standards. This deficiency
or limitation may cause a lowering of the level of one or more quality
factors or a disruption of the balance of factors essential in the raw material for malt. Studies on the effects of environment on malting quality factors show that kernel protein content is among the factors affected to the
greatest extent and that diastatic enzymatic level is among those factors
affected least. Because of the seasonal effect on physical and chemical
properties of malting barley, the commercial malting industry periodically
adjusts its raw material procurement standards in order to obtain the
best material available. This adjustment, of course, causes some changes
in malt user specifications and commercial plant operations in order to
produce their desired end products.
As expected for any biological entity, the genotype x environment component of variability contributes to levels of performance of barley quality.
References listed previously in this section indicate the significance of
many first-, second-, and third-order interactions, and genotypes usually are
involved in these interactions. Although agreements are noted among certain interactions, discrepancies can be expected because varieties of different maturities and physiological types are involved, and because of very