Barley Types: Classifications, Forms, and Uses

Barley is classified along several overlapping axes: the number of fertile rows on its seed head, its growth habit, whether its hull clings to the grain, its starch profile, and even its color. These biological classifications shape how each variety performs in the field, in the malt house, and on the plate. Add the many ways barley is processed after harvest and you get a crop with an unusually wide range of end uses, from animal feed and bread flour to biofuel pellets and tea.

Two-Row Versus Six-Row

The most visible way to sort barley is by its spike, the cluster of grain at the top of the stalk. In two-row barley, only the central floret at each node develops into a plump kernel, producing two neat lines of grain running down the head. In six-row barley, all three florets at each node are fertile, so six lines of kernels spiral around the spike. The difference is governed primarily by a single gene locus on chromosome 2 known as vrs1, along with a secondary locus on chromosome 4 called int-c. Research on doubled-haploid lines from a cross between the two-row cultivar Harrington and the six-row cultivar Morex confirmed that regions on both chromosomes influence kernel size and shape, and that the genetic architecture of grain dimensions differs between the two types even when they share much of their genome.¹

Two-row barley generally produces larger, more uniform kernels with a higher starch-to-protein ratio, which is why the malting and craft-brewing industries favor it. Six-row barley tends to be higher in protein, which increases its enzymatic power during malting and makes it useful in mashes that include unmalted grains. Feed barley, where uniformity matters less, often comes from six-row cultivars as well. For a home cook or someone shopping for pot barley, the row number rarely appears on the label, but it quietly determines the kernel shape and cooking characteristics of what ends up in the pot.

Growth Habit

Barley also divides into winter, spring, and facultative types based on how the plant transitions from leafy growth to flowering. Winter barley is sown in autumn and requires a prolonged period of cold before it will flower, a process called vernalization. Spring barley skips that requirement and can be planted after the last frost. Facultative barley occupies a middle ground: it tolerates cold like a winter type but does not need it to flower.

The molecular basis for these habits centers on two main gene loci. The candidate gene for one of them, VRN-H1, encodes an identical protein across all three growth habits, but spring varieties carry a deletion in a regulatory region that changes when the gene is expressed.² The second locus, VRN-H2, is physically deleted from the genome of both facultative and spring types, which is why neither group needs a cold spell to flower. A study of recombinant lines showed that these known vernalization genes account for only about 38% of the variation in cold requirements, with unknown genes explaining the rest.³ That gap matters to breeders: it means simply stacking the “right” alleles at the big-name loci does not fully predict how a variety will behave in the field.

For farmers, the choice between winter and spring barley is partly about climate and partly about market. Winter barley generally yields more because it has a longer growing season, but it risks winterkill in harsh climates. Spring barley dominates in short-season northern regions and is the standard choice for premium malting grain.

Hulled Versus Hulless (Naked) Barley

After threshing, hulled barley retains a tough outer husk that is fused to the grain. Hulless, or naked, barley sheds its hull freely during threshing, much like wheat does. The difference comes down to whether the palea and lemma adhere tightly to the seed’s outer surface at maturity.⁴ Most commercial barley worldwide is hulled, and the hull plays an important practical role in brewing: it forms a natural filter bed during lautering, the step in which liquid wort is separated from spent grain.

Hulless barley is more appealing for direct food use because it needs less processing to become edible. It also stores better in some respects. Imaging studies using X-ray and infrared techniques found that hulled barley varieties showed more deterioration in microstructure during storage than hulless varieties, and that those structural changes correlated with nutrient losses.⁵ For anyone buying whole barley to cook at home, hulless types cook faster and deliver more of the grain’s original nutrients with less prep.

Starch Types and Why They Matter

Within any row type or hull classification, barley can also vary dramatically in its starch composition. Normal barley starch contains roughly 25–30% amylose, the straight-chain component, and 70–75% amylopectin, the branched component. Waxy barley has almost no amylose, while high-amylose varieties push their amylose content above 40%.⁶

These differences ripple through the grain’s behavior in cooking, baking, and digestion. Waxy barley is stickier when cooked and gelatinizes at a similar temperature to normal barley but with different viscosity. High-amylose barley resists digestion more, producing what nutritionists call resistant starch, which passes through the upper gut largely intact and ferments in the colon. Growth conditions further tune starch properties: higher growing temperatures raise gelatinization temperatures across all starch types.⁷ So the same cultivar planted in a cool maritime climate versus a hot continental one can yield grain with meaningfully different cooking behavior.

Colored Barley Varieties

Most barley is pale yellow, but pigmented varieties in purple, blue, and black have attracted growing research interest. The pigments are anthocyanins, the same class of compounds found in blueberries and red cabbage, and their concentration varies strongly by color. Purple barley carries the highest total phenol, flavonoid, and anthocyanin levels among the four color groups, with its dominant anthocyanin being cyanidin-3-glucoside.⁸ Blue and black barley, by contrast, are richer in delphinidin-3-glucoside.⁹

The practical relevance goes beyond antioxidant scores in a lab assay. Purple barley phenolic fractions showed the strongest ability to inhibit alpha-glucosidase, an enzyme involved in carbohydrate digestion, while black barley anthocyanins were even more potent when isolated. Transcriptomic work comparing black and blue barley found that the dramatic difference in cyanidin-3-O-glucoside content between the two colors traces to differential expression of genes in the anthocyanin biosynthesis pathway.¹⁰ Colored barley varieties are still niche, but they are increasingly turning up in specialty flour blends and whole-grain products marketed for their polyphenol content.

What Pearling Does to the Grain

Pearled barley is the form most people recognize from grocery shelves. Pearling is an abrasive milling process that strips away the outer bran layers in stages. The more you pearl, the whiter and smoother the grain becomes, and the faster it cooks. But you also lose nutrients unevenly. Protein, oil, ash, total phenolics, and total flavonoids all drop with increasing pearling, while starch and amylose increase because the starchy endosperm makes up a larger share of what remains.¹¹

Beta-glucan, the soluble fiber that gives barley its health reputation, behaves differently from most other nutrients during pearling. It is concentrated in the inner endosperm cell walls rather than the outer bran, so its proportion actually rises slightly as outer layers are removed.¹² Dietary fiber more broadly, however, follows the usual pattern: highest in the outer fractions and declining inward. One study that pearled two hulled barley varieties in eight sequential 5% passes showed fiber dropping from the outside in, while beta-glucan rose.¹³ That same study noted that mycotoxin contamination, specifically deoxynivalenol, concentrated in the outermost fractions, so pearling also has a food-safety benefit.

For home cooks, the trade-off is straightforward: pot barley (lightly pearled) keeps more fiber and cooks in about 40–50 minutes, while fully pearled barley cooks in around 20–30 minutes but loses some of its nutritional edge. Hulless barley sold whole splits the difference.

Barley Flour in Baking

Barley flour lacks the strong gluten network that wheat flour builds, which limits its use in leavened bread. When hulless barley flour replaces 10–40% of wheat flour, the dough’s gluten microstructure is partially disrupted and development time shortens, producing weaker, less elastic dough.¹⁴ The doughs also rupture at lower extensions under stretching tests. But at moderate levels, around half or less of the flour blend, the effect on loaf volume and crumb texture is not dramatic, and the loaves gain a meaningful bump in dietary fiber and beta-glucan.¹⁵

Beyond bread, barley flour and flakes work well in flatbreads, noodles, cookies, and muffins, where a towering rise is not the goal. Barley has been described as having great potential as a partial or full replacement for wheat, oats, rice, or corn in a wide range of cereal-based products.¹⁶ Flatbreads, in particular, are a natural fit because they do not depend on gluten strength for their structure.

Malting Barley and What Brewers Look For

Malting converts raw barley into malt by soaking the grain, allowing it to germinate briefly, and then kilning it dry. The germination phase activates enzymes that break down the grain’s starch reserves, and the overall enzymatic power of the resulting malt is measured as diastatic power. Across 11 Australian cultivars grown in six locations, grain nitrogen content was the strongest single predictor of diastatic power, largely through its relationship with beta-amylase activity.¹⁷ However, high nitrogen also correlated with smaller grains and lower extract yield, which is the amount of fermentable sugar the brewer actually gets. That tension between enzyme activity and extract is one reason maltsters are so particular about the barley they accept.

A study of Indian cultivars found that malting boosted diastatic power roughly twofold, from an initial range of about 59–81 to 116–142 degrees Lintner, and increased soluble protein while dramatically raising alpha-amylase activity.¹⁸ Beta-glucan content dropped 70–80% during malting across genotypes, which is desirable because residual beta-glucan causes filtration problems in the brewery. Two-row barley is the workhorse of craft and European brewing for its plump kernels and cleaner flavor profile, while six-row barley, with its extra enzyme reserves, traditionally supports the high-adjunct mashing schedules common in large-scale North American brewing.

Barley as Livestock Feed

Globally, more barley goes to animal feed than to any single human food category. For ruminants like cattle and sheep, barley is the third most rapidly degradable cereal after oats and wheat. Its faster starch fermentation compared with corn leads to a more synchronized release of energy and nitrogen in the rumen, which improves how efficiently microbes assimilate nutrients. That efficiency can reduce the need for expensive bypass-protein supplements, but only if rumen pH stays above roughly 5.8 to 6.0; below that threshold, the benefit disappears as microbial maintenance costs rise and wastage increases.¹⁹

There is also a ceiling on how much barley starch a ruminant diet can comfortably contain. In fattening sheep, total tract digestibility of dry matter, fiber, and starch all declined as the proportion of barley starch in the diet increased, with a particularly sharp drop when the diet was entirely barley-based.²⁰ Moderate inclusion levels performed nearly as well as corn-based controls, but pushing to 100% barley starch undermined digestion. The practical takeaway for livestock producers: barley is an excellent and often cheaper energy source than corn, but ration formulation matters.

Barley, the Gut Microbiome, and Beta-Glucan

Much of barley’s nutritional reputation rests on beta-glucan, a soluble fiber concentrated in the endosperm cell walls. In animal studies, whole-grain barley increased the pool of short-chain fatty acids in the cecum and shifted the microbial community toward beneficial species like Lactobacillus while reducing inflammatory markers in blood.²¹ Highland barley fiber fed to mice on a high-fat diet significantly reduced weight gain and improved glucose tolerance, while restoring gut microbiota disrupted by the fatty diet, with increases in beneficial groups like Akkermansiaceae and Lachnospiraceae.²²

Human data points in a similar direction. When people consumed pasta containing about 3% barley beta-glucans, their fecal samples showed higher levels of short-chain fatty acids, more culturable lactobacilli, and lower counts of several potentially harmful bacterial groups compared to a standard pasta diet.²³ A trial in mildly hypercholesterolemic adults found that concentrated barley beta-glucan reduced hunger levels and modestly shifted the cholesterol-to-HDL ratio, though the effects differed depending on whether the beta-glucan had high or low molecular weight.²⁴ The molecular weight distinction is worth knowing about: processing that chops beta-glucan chains into shorter fragments can change the physiological response.

Barley Tea and Other Beverages

Beer gets most of the attention, but barley has a long history in non-alcoholic beverages as well. Barley tea, made by steeping roasted barley grains in hot or cold water, is a staple in China, Japan, and Korea. Often called “Oriental coffee” for its toasty, malty flavor, barley tea contains phenolic compounds that have shown antioxidant activity in lab assays.²⁵ In the Ethiopian highlands, barley’s beverage repertoire is even broader. Ethnobotanical surveys documented more than 20 distinct barley-based dishes and drinks prepared from boiled, roasted, or cracked grain, earning barley the local title of “king of crops.”²⁶

Salt Tolerance and Climate Resilience

Barley stands out among cereals for its tolerance to salt stress. It has been called the fourth most important cereal crop in the world and possesses outstanding salinity tolerance relative to other cereals, a trait linked in part to greater diversity in a family of stress-response genes called DREBs.²⁷ Wild Tibetan barley accessions push this resilience even further. When subjected to drought and salinity simultaneously, two wild genotypes maintained higher potassium levels, lower sodium-to-potassium ratios, and stronger antioxidant enzyme activity than a cultivated variety, resulting in less oxidative damage.²⁸

These traits have real implications as arable land faces rising salinity from irrigation and climate shifts. Wild barley relatives are essentially a genetic toolkit for breeding tougher cultivated varieties, which is one reason gene banks and in-situ conservation of wild barley populations in places like Tibet and the Fertile Crescent remain a priority.

Domestication and the Deep History of Barley

Barley was one of the very first crops humans domesticated, roughly 10,000 years ago, in the Fertile Crescent. Analysis of 400 polymorphic loci across hundreds of wild and cultivated lines demonstrated that domestication was monophyletic, meaning it happened once, and that wild populations from the Israel-Jordan area are the most genetically similar to the cultivated gene pool.²⁹ Genomic sequencing of 6,000-year-old barley grains excavated from a cave near the Dead Sea confirmed this picture: the ancient samples were most closely related to present-day landraces from the southern Levant and Egypt, and current Israeli landraces have not experienced major lineage replacement over six millennia.³⁰ That continuity is remarkable and highlights how stable barley cultivation has been in the region where it began, even as gene flow between cultivated and neighboring wild populations continued throughout that time.

Industrial Uses Beyond Food and Feed

Barley straw, the stem residue left after grain harvest, is finding new roles in energy and materials. Torrefied and pelleted barley straw, especially with a biochar and polymer binder, can reach heating values above 28 MJ per kilogram, approaching the energy density of low-grade coal.³¹ The treatment also reduces moisture absorption, which is a practical advantage for storing biofuel pellets in humid climates.

Barley straw fiber has also been tested as reinforcement in biobased plastic composites. Its high cellulose content and favorable fiber aspect ratio make it a candidate to replace wood fiber in applications where deforestation and forest degradation are concerns.³² These are still early-stage applications, but they illustrate how every part of the barley plant, not just the grain, is a usable resource.

Mycotoxin Risk in Stored Barley

One issue that cuts across all barley types is Fusarium infection and the mycotoxin deoxynivalenol (DON) it produces. Fusarium can infect a high percentage of kernels in the field, and the contamination persists through storage. A study that tracked infected malting barley over seven months under different storage conditions found that all conditions reduced Fusarium viability to some degree, but forced-air ventilation at 24°C was the most effective, dropping infection rates from 85% to 66%. DON levels did not change during storage itself, but malt produced from barley stored at elevated temperatures had lower DON levels than malt from cold-stored grain, suggesting that warm on-farm storage can be a practical strategy for reducing mycotoxin risk in finished malt.³³

Pearling offers a complementary defense: because Fusarium and its toxins concentrate in the outermost grain layers, removing even the first 15% of the kernel by pearling strips away a disproportionate share of the contamination. For end users buying whole or lightly pearled barley, sourcing from reputable suppliers who test for DON remains the most reliable safeguard.