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VII. Requirements of Malting Barley

VII. Requirements of Malting Barley

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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

United States.






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-



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



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.


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

from malt.




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



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.





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



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

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VII. Requirements of Malting Barley

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