The science of barley, particularly as it pertains to the brewing of beer, is a subject of immense complexity and historical significance. Barley is one of the oldest cultivated grains, dating back thousands of years, and has been used in various culinary applications ranging from bread-making to beverage production. In the context of beer brewing, barley serves as a foundational element that contributes to the beer’s flavor, aroma, color, and alcoholic content. Understanding the intricate details of barley’s biology, chemistry, and processing is therefore essential for anyone seeking to master the art and science of brewing.
Barley is a cereal grain that belongs to the grass family. It has a unique set of characteristics that make it ideal for brewing, including a high starch content, sufficient enzymatic activity, and a husk that aids in the filtration process during brewing. The grain consists of several key components: the endosperm, which contains the majority of the starches and proteins; the germ, which is the reproductive part of the grain; and the husk, which encloses the other parts of the grain. Each of these components plays a distinct role in the brewing process and affects the final quality of the beer in specific ways.
The starch in barley’s endosperm serves as the primary source of fermentable sugars, which are necessary for the production of alcohol and carbon dioxide during fermentation. Enzymes, which are proteins that catalyze chemical reactions, facilitate the conversion of these starches into simpler sugars like glucose and maltose. This enzymatic activity is critical, as it dictates how efficiently the starches are converted, ultimately impacting the beer’s alcoholic content and body.
Before barley can be used for brewing, it must undergo malting, a controlled germination process that activates the enzymes in the grain and makes the starch more accessible. Malting begins with soaking the barley grains in water, followed by a period of germination where the activated enzymes start breaking down the starches and proteins. This is then halted by drying the malt in a kiln, a process that also develops the color and flavor of the malt. The degree of kilning can significantly affect the malt’s characteristics; for example, a lightly kilned malt will produce a pale beer with a delicate flavor, while a heavily kilned malt will result in a darker beer with robust flavors.
Barley (Hordeum vulgare) is a tall grass, usually ranging from 2 to 4 feet in height, that grows annually. It has two kinds of root systems: seminal roots, which are the first to grow from the seed, and adventitious roots, which develop later. How deep these roots go into the ground depends on several factors, such as soil quality and temperature. Usually, the deepest roots come from the original seed, while the roots closer to the surface are the later-developing adventitious ones.
If you plant the barley seed deep into the soil, a special kind of stem called a ‘rhizome’ forms. This stem grows underground until it reaches the surface, where it starts to produce leaves. This rhizome can also have its own adventitious roots and can vary in length.
The stem of the barley plant stands upright and is hollow inside. It is made up of sections called internodes, which are separated by nodes that hold the leaves. A fully grown barley plant has one main stem and 2 to 5 smaller stems called ’tillers.’ Each of these stems and tillers ends in a spike, which is the part of the plant that contains the grains. Near the ground, the part of the stem that holds the base of the leaves swells to form what is known as the ‘crown.’ This crown is where new roots and tillers start to grow.
As for the leaves, they are long and narrow, measuring about a half-inch to a little over half an inch in width. The leaves grow out from alternating sides of the stem. Each leaf is made up of several parts: the sheath, which wraps around the stem; the blade, which is the flat part; and two smaller parts called the auricles and ligule. What sets barley apart from other cereal grains are its smooth ligule and auricles. These parts wrap around the stem and can sometimes even have a purplish color due to the presence of pigments called anthocyanins.
The flowering part of the barley plant is known as the ear, head, or spike. It has a central stem-like structure called the rachis, which holds the spikelets, or the small flowering units. These spikelets grow in groups of three at each bump or “node” on the rachis, and they alternate from one side to the other.
Each spikelet contains two empty leaf-like parts called glumes and a small flower called a floret. This floret has several parts, including the lemma and the palea, which surround the actual reproductive parts of the flower. Some types of barley have spikelets with long, hair-like extensions called awns, while others do not. Some types of barley also have grains that are covered by the lemma and palea, known as hulled barley. In other varieties, these coverings are easily separated, and these are known as hull-less or naked barley.
There are two main kinds of barley based on the fertility of the spikelets: six-row and two-row barley. In six-row barley, all three spikelets at each node can produce grains. These grains can vary in shape; the central grain is usually round, while the side grains might be a bit uneven. In two-row barley, only the middle spikelet at each node is fertile and can produce a grain, while the two side spikelets are sterile. This gives two-row barley a flatter appearance. Depending on the type, a single barley spike can produce anywhere from 15 to 60 grains.
When you pull up a fully grown barley plant from the ground, you can usually still see the remains of the original grain that grew into the plant. This is found among the plant’s roots and is identifiable by a part called the scutellum. Starting from this original grain, you’ll see about 5 to 10 thin roots. These first roots grow straight and also have some tiny offshoots. They help the young plant get nutrients and stay anchored to the soil until the plant can grow more complex roots.
As the barley plant matures, these first roots fade away and lose their role in transporting nutrients. On the opposite side of the grain, there’s a stem-like part called the mesocotyl. It varies in length and connects the original grain to the base of the plant, known as the crown. From the crown, the plant grows its main stems and a new set of roots. The length of the mesocotyl depends on how deep the grain was planted in the soil. Sometimes it can even be missing, which has led some experts to question if it really exists in barley plants.
The new roots that grow from the base of the stem are different from the first roots. They are thicker and don’t grow straight; instead, they twist and turn and have many branches. These roots can penetrate deep into the soil, sometimes nearly a meter down if the soil is loose enough. Both the first roots and these new roots have hair-like extensions that help the plant absorb water and nutrients.
Under a microscope, the structure of barley roots is quite intricate but hasn’t been extensively studied. It’s known that the roots contain two kinds of wood-like vessels that help transport water and nutrients. These vessels are arranged in a specific pattern inside the root and are surrounded by other tissues.
The barley stem is similar to other grasses and is made up of seven to eight segments, each separated by a node, which is a joint-like structure. These nodes are noticeable because they are slightly swollen. This swelling comes from the leaf tissue that attaches at these points, and the leaf also wraps around most of each segment for added support. The stem grows mainly at the lower end of each segment, which stays flexible even after the plant has flowered. This flexibility helps the plant correct itself if it leans over.
The length of each segment increases as you move from the base of the stem to the top. If you look at a cross-section of a segment, you’ll find several layers. The outermost layer is a skin of tough cells. Below this are fibrous cells that provide strength. You’ll also see two rings of tubes that help transport water and nutrients; one ring is near the outer layer and the other is more towards the center. In between these tubes are various other cells, some of which become hard as the plant gets older.
The stem is actually quite delicate and not very stiff. This means barley plants are more likely than other grains to fall over, especially under certain conditions. The plant’s structure allows it to have multiple stems, which can vary depending on the growing conditions and the specific type of barley. Each stem usually produces a flowering head, known as an ear, although late-developing stems may not do so.
Some unique barley plants have a “branching” form. In these plants, stems don’t just grow from the base but also sprout from various points along other stems, leading to a complex network of stems, each capable of producing an ear. This feature can influence how much the plant yields.
Grass leaves, including those of barley, are different from leaves of other types of plants in their structure and functions. They not only play the typical roles of taking in and releasing substances but also protect the grain and give support to the stem. In grasses, it’s hard to distinguish between the main flat part of the leaf, called the blade, and the stalk-like part called the petiole, which you can easily identify in other plants.
A barley leaf wraps around the stem at its base in a part known as the leaf sheath. Above that, the blade sticks out at an angle. Where these two parts meet, there is a thin, transparent strip called the ligule. There are also two flap-like structures called auricles at the base of the blade, which can sometimes be colored purple in certain barley varieties.
The bottom part of the leaf sheath forms a collar-like structure called the pulvinus at the point where it attaches to the stem. Unlike other areas, it doesn’t have pores for gas exchange, known as stomata, and it may contain colored pigments but usually lacks the green pigment chlorophyll. Some barley types may have hairs on the leaf sheath, especially the winter varieties.
The blade of the leaf has a ribbed structure, with a central rib and several secondary ones running parallel to it. The blade can be V-shaped in its cross-section. Different barley varieties have blades that differ in size and angle relative to the stem, which is particularly noticeable in the last leaf, known as the flag leaf. This flag leaf has a well-developed sheath that protects the young grain as it develops.
At a cellular level, the leaf’s anatomy resembles that of the stem. The surface of the leaf is lined with rows of stomata, which are separated by cell rows lacking stomata. Below the surface, there are specialized cells that provide support and are similar to those found in drought-resistant grasses. The internal structure of the leaf is mostly made up of cells containing the green pigment chlorophyll and has air spaces in between.
The barley ear is actually a specialized part of the stem designed to hold the flowers and later the grains. In grasses like barley, the flowers are quite simple, lacking many features commonly seen in other flowering plants. Instead of having petals and sepals, the barley flower is primarily protected by leaf-like structures called bracts.
A barley ear is made up of multiple smaller flower clusters, known as spikelets. Each spikelet is attached to the main stem, or axis, of the ear by a small stalk. The spikelet itself has two main bracts at its base, known as glumes. Inside these glumes, the stalk extends to form another axis, on which the actual flower sits, protected by additional bracts called paleae.
Barley ears follow a few specific characteristics:
Overall barley ear is a complex but organized structure that is optimized for protecting and supporting its grains.
The rachis is the part of the barley stem that holds the grain. Unlike the main stem, its segments are short and symmetric. It also doesn’t have a hollow center. At the point where the rachis connects to the main stem, there’s a thicker area known as the “collar.” This collar is a leftover part of a leaf that didn’t fully grow, and its shape can help identify different types of barley. The first segment of the rachis is different from the others; it’s less flat and more like the segments in the main stem.
Along the collar, you’ll find small groups of grain buds that usually don’t grow fully. The number of segments in the rachis can vary based on growing conditions and the type of barley. Usually, each ear of barley has similar-looking segments. The length of these segments affects how tightly the grains are packed. They’re usually trapezoid-shaped, and the grain buds attach to the wider top part. The segments aren’t perfectly aligned; they overlap slightly, making the rachis a fragile structure. In some wild barley species, the rachis breaks apart easily when the grains are mature.
Some variations exist in cultivated barley types. For example, some have a branching rachis, a feature passed down through generations. Sometimes this occurs by chance, especially when spring barley is planted in the winter. There are also some barleys with irregularly shaped rachis segments. This is common in a specific mutation and rare in certain American varieties. Chemicals like 2-4-D can also cause these irregular shapes.
In barley plants, the small flower-like structures called spikelets appear in groups of three at each joint of the stem, also known as the node on the main axis or rachis. This set of three is the basic building block of the barley’s ear. Due to this arrangement, the protective outer layers, known as glumes, are positioned on the side facing away from the main stem.
Among these groups of three spikelets, the one in the middle is the most straightforward in design and often contains a fertile flower that can reproduce. The two on the sides can be a bit irregular; they can twist in opposite directions and may contain a flower that may or may not be fertile. When describing these structures, it’s best to start with the middle spikelet and discuss the side ones later.
At the base of each spikelet, there are two glumes that protect it. In most common types of barley, these glumes are quite small and uniform in shape. They are narrow, about one millimeter wide, and often have long, hair-like projections called awns. However, the fragility of these awns makes them unreliable for identifying specific varieties of barley.
Some rare varieties of barley have unusually large glumes. For instance, in a specific type of six-row barley from Morocco, the glumes grow so large that they almost completely enclose the grain, resembling another protective layer. This phenomenon of larger glumes can also be found in some two-row barley varieties.
In the Hordeae tribe, a group of plants including barley, the palea plays a significant role. It serves as a protective covering for the flower. The bottom part of the palea, known as the lemma, is large and lance-shaped, and it usually has a long, pointed extension called an awn. These awns and other features, such as small pointed structures called spicules and hairiness, can help identify different barley varieties. The awns can differ in length within the same barley ear, being shorter at the top and bottom. This length can also help categorize different types of barley, especially the six-row varieties.
Awns serve a dual purpose: they protect the barley grains from predators like birds and help release water as the grain matures. Some barleys don’t have traditional awns but instead have a complex structure often called a “hood” by English authors or “Kapuze” by Germans. This hood has additional structures that look like secondary awns, giving it a forked appearance.
Interestingly, in some barley varieties, the place where the hood joins the normal part of the palea is unusually thick. This area may also develop additional small scales and even extra stamens or ovaries, although these rarely turn into actual grains. This is unusual because it shows that flower buds can sometimes develop in leaf-like organs, not just in the main stem of the plant.
The ventral palea, also known simply as the palea, is a leaf-like structure with three ridges and a blunt top. It doesn’t have a pointed extension known as an awn. A deep groove is present in the middle of this structure, which holds another part called the rachilla. This rachilla is pressed closely against the main stem, known as the rachis. The rachilla is usually shorter than half the length of the barley grain and can have different types of hair on it—either long and silky or short and stiff.
Understanding the structure of a barley flower is not straightforward when trying to fit it into the standard framework used for flowers of plants with one initial leaf, known as Monocotyledons. This traditional framework usually includes three sepals, three petals, six stamens, and two ovaries. The barley flower doesn’t neatly fit into this pattern. To better understand it, one should look at other types of grasses, especially Bamboos, where the flower structure is less simplified.
In barley, after the seed is fertilized, the ovary expands to fill the space between the paleae, which are like protective husks. In many European barley varieties, the ovary wall sticks closely to the paleae, leading to a “covered” grain. This characteristic sets European barley apart from other grains like wheat and rye, but it’s not a universal trait. In some Asian varieties, for example, the ovary and the paleae don’t stick together, leaving a “naked” grain. Interestingly, it seems that “naked” grains were more common in ancient times.
The barley grain is actually a type of dry fruit known as a caryopsis. It’s made up of different parts including the paleae and a structure called the rachilla. As the grain matures, it shrinks, causing the paleae to wrinkle. These wrinkles can tell us about the quality of the barley for brewing; even, fine wrinkles usually mean the barley is good for making beer.
If you cut the grain open, you’d see that the endosperm cells are full of simple and complex starches. As the grain matures, these cells break down into a network that holds the starch grains. Around the edge of the endosperm is a layer called the aleurone layer, rich in proteins and enzymes that help the young plant use the starch.
The barley grain is a complex structure with various components that play crucial roles in its development and its suitability for brewing. Its unique features, such as the multi-layered aleurone and specialized embryo, make it a preferred choice for brewing since ancient times.
ALEURONE: The aleurone is a specialized layer of cells that surrounds the endosperm in a barley grain. This layer plays a pivotal role in the germination and development of the barley plant, as well as in the brewing process. During germination, the aleurone layer becomes active and secretes enzymes that help break down the starches stored in the endosperm into simpler sugars. These sugars serve as an energy source for the growing embryo. The aleurone layer is rich in proteins and other nutrients. When it comes to brewing, the enzymes produced by this layer are particularly important for starch conversion, a process that is essential for the production of malt and, ultimately, beer. In barley, the aleurone layer is unique because it often consists of multiple rows of cells, as opposed to the single row commonly found in other cereal grains. This feature contributes to barley’s suitability for brewing, as the extra layers typically result in higher levels of enzymes conducive to efficient starch-to-sugar conversion. Additionally, the aleurone cells contain small reserves of fatty substances and are free from starch, distinguishing them from the starch-rich cells of the endosperm. Because of its role in providing essential enzymes and nutrients, the aleurone is considered a crucial component in both the biological development of the barley grain and its practical application in brewing.
EPITHELIUM: The epithelium is a specialized layer of cells situated at the interface between the endosperm and the scutellum of the embryo. The scutellum is a shield-like organ that is part of the embryo and is essential for the seed’s development. The epithelium serves a crucial role in secreting enzymes that help break down the starches in the endosperm into simpler sugars. These sugars are then absorbed by the scutellum and used by the growing embryo for nourishment and development. The epithelium shares this enzymatic function with the aleurone layer, another layer of cells that surrounds the endosperm. Both layers produce enzymes that catalyze the conversion of complex carbohydrates into simpler forms, a key process particularly during the malting stage of brewing, where the starch needs to be converted into fermentable sugars. However, the epithelium is more directly associated with the embryo and is essential for its nourishment.
SCUTELLUM: The scutellum is a specialized structure that is part of the seed’s embryo. It serves as a critical intermediary between the embryo and the endosperm, the starchy portion of the seed. In botanical terms, the scutellum is considered a modified cotyledon, or seed leaf, although its functions in monocots like barley differ somewhat from the cotyledons found in dicots, such as beans. The primary role of the scutellum is to facilitate the transfer of nutrients from the endosperm to the growing embryo during germination. It is situated adjacent to the endosperm and is involved in secreting enzymes that break down the starches and proteins in the endosperm into simpler molecules like sugars and amino acids. These simpler substances are then absorbed by the scutellum and transferred to the developing embryo, providing the energy and building blocks it needs to grow. The scutellum also has a unique morphology. It is typically shield-shaped and is in contact with specialized tissues that are capable of producing enzymes. These enzymes are pivotal in the conversion of the stored materials in the endosperm into forms that can be utilized by the emerging seedling.
PLUMULE: The plumule refers to the embryonic shoot that will eventually develop into the first true leaves of the plant. It is a crucial part of the barley embryo and represents the initial structure from which the above-ground parts of the plant will grow. In the embryonic stage within the seed, the plumule is typically covered by a protective sheath, allowing it to safely emerge when conditions are favorable for germination. The emergence of the plumule is a significant milestone in the life cycle of a barley plant. When the seed germinates, the plumule breaks through the protective layers surrounding the seed and begins to grow upwards, eventually forming the leaves and the stem. This upward growth allows the young plant to access sunlight, which is essential for photosynthesis, the process by which plants convert light energy into chemical energy stored as carbohydrates. Therefore, the plumule serves as a critical structure in the early development of the barley plant, initiating the growth of the above-ground vegetative structures that are essential for the plant’s survival and eventual reproduction.
RADICLE: The radicle refers to the initial root that emerges from the seed during the process of germination. In the context of a seed, the radicle is part of the embryo, which is the young plant contained within the seed. Upon the appropriate conditions for germination, including the availability of water, the radicle is the first structure to emerge from the seed coat. Its primary function is to anchor the seed in the soil and to begin absorbing water and nutrients, thus facilitating the further growth and development of the plant. The emergence of the radicle is often considered the first visible sign of successful germination and serves as a preliminary step for the later emergence of other parts of the plant, such as the shoot, leaves, and additional roots. Overall, the radicle plays a vital role in the early stages of plant development by establishing the plant’s connection to the soil environment, setting the stage for further growth and maturation.
TESTA (SEED COAT): The testa is essentially the seed coat that lies immediately adjacent to the endosperm and embryo inside the grain. It serves as a semi-permeable membrane, meaning that it allows some substances to pass through while blocking others. Specifically, the testa is permeable to water but generally impermeable to dissolved salts and other solutes. This selective permeability is important for the germination process, as it allows water to enter the seed, thereby activating the enzymes and other biochemical processes that enable the seed to sprout into a new barley plant. The testa is derived from the inner integument of the ovule, which is the part of the seed that becomes fertilized to eventually develop into the grain. In barley, the testa often fuses with the outer layer, known as the pericarp, and sometimes also with the protective husks, or paleae, that surround the grain. This fusion creates a more or less continuous outer covering for the seed, offering an additional layer of protection and contributing to the grain’s overall structure.
ENDOSPERM: The endosperm is a tissue that serves as a primary storage reserve of nutrients, primarily in the form of starch granules. This starch is intended to provide the growing embryo with the energy it needs until the young plant can develop leaves and initiate photosynthesis. The endosperm is situated within the seed, and it is surrounded by other key components like the germ, or embryo, and the seed coat, which includes the hulls.
The cells of the endosperm are unique in that they are generated from the fusion of three different nuclei—a process that results in a tissue with a triploid genetic makeup. This feature makes the endosperm somewhat unusual in the plant world. During the grain’s maturation, the cellular structure of the endosperm undergoes significant changes, breaking down to form a complex network that holds the starch granules. These granules are semi-crystalline, meaning they have both crystal and non-crystal regions, and they are each surrounded by a protein-rich matrix. Additionally, the endosperm is encased by a layer known as the aleurone layer. This layer is rich in proteins and enzymes, particularly those that are capable of converting starch into simpler sugars. This enzymatic activity is crucial during the malting process, where the breakdown of starches into fermentable sugars is a key step. In barley, the aleurone layer often consists of multiple rows of cells, making it especially rich in enzymes that facilitate starch hydrolysis.
PERICARP: The pericarp is the outermost layer of a barley grain, originating from the ovary wall. Its primary function is to act as a shield for the seed, offering protection from both physical harm and microbial threats. In barley, this layer typically merges with other protective layers, such as the testa and paleae, creating a multifaceted barrier around the inner elements of the grain—specifically the endosperm and the embryo. Although the pericarp is not a significant source of nutrients or starch, its protective role is crucial for the integrity of the grain’s inner contents. Within the scope of brewing and malting, the characteristics of the pericarp are important because they can influence how water is absorbed during the malting stage. This, in turn, affects enzyme functionality and the conversion of starch into sugars. Consequently, a thorough understanding of the pericarp’s properties and functions is key to optimizing the brewing process.
LEMMA, PALEA: The lemma and the palea are specialized bracts that enclose the seed or grain, acting as protective coverings. Together, they form the floret, which is a part of the spikelet, the basic unit of the inflorescence in grasses. The lemma is the lowermost and usually the larger of the two bracts. It is often lanceolate (shaped like a lance’s tip) and may have various surface textures. The lemma might also have an extended structure called an “awn,” sometimes referred to as a “beard,” which can aid in the dispersion of the seed and protect it from herbivores. The palea, on the other hand, is positioned opposite the lemma and is generally smaller. It is found on the inner side of the floret, closer to the seed or grain itself. Like the lemma, the palea can have a variety of forms but is usually more simple in structure compared to the lemma. Both the lemma and the palea play a crucial role in protecting the developing seed and can be significant for the plant’s reproductive success. They also serve as valuable taxonomic features, as different species of grasses can often be distinguished by the unique characteristics of their lemmas and paleas. Furthermore, in the case of barley, the form and texture of these components can also have implications for its suitability for various uses, including brewing.
EMPTY CELLS: The term “empty cells” generally refers to the cells in the endosperm region that are located close to the embryo. During the growth and maturation phase of the barley grain in the field, these cells are emptied of their contents, which are utilized by the developing embryo. In other words, the nutrients and other substances within these cells are consumed to support the growth and development of the new plant that will arise from the embryo. In a typical barley grain, the endosperm serves as a storage reservoir for starch, which provides the energy needed for the embryo to germinate and grow until it can carry out photosynthesis on its own. The endosperm is actively engaged in nourishing the embryo, especially during the critical phases of germination. As a result, the cells close to the embryo are often emptied of their content, as the stored materials are mobilized and transported to support the young plant. The emptying of these cells is an essential part of the natural growth cycle of the barley grain and plays a pivotal role in ensuring that the embryo receives the nutrients it requires for successful germination and subsequent growth. Therefore, the presence of empty cells near the embryo is an indicator of this natural process of resource allocation within the grain.
EMBRYO: The embryo is the part of the seed that will develop into a new barley plant. Located at the base of the grain, the embryo contains the genetic material and the initial structures needed for germination and growth. When the conditions are right, such as the presence of water and suitable temperature, the embryo activates and begins to grow. During this process, it relies on nutrients stored in another part of the seed called the endosperm. The embryo consists of several components including the radicle, which will grow into the root system of the plant, and the plumule, which will develop into the shoot and eventually produce leaves. In barley and other grasses, the embryo also has a unique structure called the scutellum. The scutellum is a shield-shaped organ that lies next to the endosperm and helps in absorbing nutrients from it. This is particularly important in the initial stages of germination where the embryo needs energy and nutrients for rapid growth but has not yet developed leaves for photosynthesis. The complexity and efficiency of the barley embryo, especially its capacity to effectively utilize stored nutrients in the endosperm, are part of what makes barley such a valuable crop for purposes like brewing. In brewing, the embryo’s role is mostly indirect; it is the endosperm that mainly provides the starches which are converted to sugars and then fermented. However, the overall health and quality of the embryo can be indicative of the grain’s viability and its potential to produce high-quality malt for brewing.
STARCH GRANULES: Starch granules are essentially compact structures that store starch, which is a carbohydrate. These granules reside within the cells of the endosperm, the part of the grain that serves as an energy reservoir for the developing plant. The stored starch in these granules can later be converted into sugar, either to nourish the growing plant or during the malting and brewing process to produce beer. The starch granules are of particular interest in both agricultural science and food technology because their size, shape, and how they are packed can influence their properties, including how easily they can be broken down into sugars. These factors can affect not only the growth and vitality of the barley plant but also the efficiency of the malting and brewing processes. In the brewing industry, the ability to break down these starch granules into fermentable sugars is a critical aspect of beer production. The conversion is facilitated by enzymes, primarily produced by the aleurone layer surrounding the endosperm. The starch granules are hydrolyzed, meaning broken down by water, into simpler sugars that can be fermented by yeast to produce alcohol and carbon dioxide. Starch granules are also noteworthy for their semi-crystalline nature. They are partly organized in a crystalline structure and partly in a disorganized, or amorphous, structure. This characteristic impacts how readily water and enzymes can penetrate the granules, affecting their digestibility and the efficiency of their conversion to sugars.