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This is the complete lecture note for BST311 Raw Materials in Brewing. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS • Course code: BST311 • Course title: Raw Materials in Brewing • Course credit load: 3 Series 1: Barley and Grain Biochemistry Series outline • Part 1: Morphology of the Barley Plant o Sub-Part 1.1: Structure and Growth Stages o Sub-Part 1.2: Position of Barley within the Graminae • Part 2: Biochemistry of the Barley Grain o Sub-Part 2.1: Composition of the Grain o Sub-Part 2.2: Enzymatic Constituents and Their Roles • Part 3: Barley Varieties and Classification o Sub-Part 3.1: Nature of Barley Varieties o Sub-Part 3.2: Classification Systems • Part 4: Brewing Relevance of Barley o Sub-Part 4.1: Contribution to Beer Composition o Sub-Part 4.2: Influence on Sensory Properties Introduction Barley has been cultivated for thousands of years and remains one of the most important cereal crops in the world. Within brewing, it is the principal raw material that shapes the quality, flavour, and character of beer. By examining barley from both a biological and biochemical perspective, you will gain insight into why it is uniquely suited for brewing and how its properties influence the sensory attributes of the final product. This Series therefore provides the foundation for understanding the science behind beer production. The aim of this Series is to equip you with the knowledge and skills needed to analyse the morphology, biochemistry, and classification of barley, and to evaluate its relevance to brewing practice.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS We shall commence this Series by exploring the morphology of the barley plant and its position within the Graminae family. Next, we will examine the biochemistry of the barley grain, focusing on its composition and enzymatic constituents. Following that, we will study the nature and classification of barley varieties. Finally, we will conclude by considering the brewing relevance of barley, highlighting its contribution to beer composition and sensory properties. Series Learning Outcomes Upon completing this Series, you should be able to: • SLO 1.1 define the morphology of the barley plant and explain its position within the Graminae family, • SLO 1.2 analyse the biochemical composition of the barley grain and describe the roles of its enzymatic constituents, • SLO 1.3 classify barley varieties using recognised systems and evaluate their distinctive features, and • SLO 1.4 assess the relevance of barley to brewing by explaining its contribution to beer composition and sensory properties. 1.1 Morphology Of The Barley Plant 1.1.1 Structure and growth stages The barley plant is a cereal crop belonging to the genus Hordeum. It is characterised by its slender stems, narrow leaves, and distinctive seed heads known as spikes, which contain rows of grains. The plant typically grows to a height of 60 to 120 centimetres, depending on the variety and environmental conditions. Barley is an annual plant, meaning it completes its life cycle within one growing season. The growth of barley can be divided into several stages: germination, seedling development, tillering, stem elongation, heading, flowering, and grain filling. Each stage is critical to the eventual yield and quality of the grain. For example, during tillering, the plant produces side shoots that increase the number of potential grain-bearing stems. During heading, the spike emerges from the stem, and this stage is particularly important for determining grain number and size.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Diagram of barley plant showing roots, stem, leaves, and spike. Figure 1.1: Morphological structure of the barley plant Fill in the blank: The seed head of the barley plant is called a __________. 1.1.2 Position of barley within the Graminae Barley belongs to the Graminae family, also known as the Poaceae, which is the family of grasses. This family includes other important cereal crops such as wheat, rice, maize, and sorghum. Members of the Graminae are characterised by their jointed stems, narrow leaves arranged alternately, and flowers grouped in spikelets. Within the Graminae, barley is classified under the genus Hordeum. The most widely cultivated species is Hordeum vulgare, which is used extensively in brewing. Its close relatives include wild barley species that are less suitable for cultivation but provide genetic diversity for breeding programmes.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Photograph of barley spikes in a field. Plate 1.1: Barley spikes at heading stage Fill in the blank: Barley belongs to the family __________, which also includes wheat and rice. Pilot questions 1.1 1. Which part of the barley plant produces the grain-bearing spikes? 2. At which growth stage does the spike emerge from the stem? 3. What is the botanical family name of barley? 4. Name one other cereal crop that belongs to the Graminae family. 5. What is the most widely cultivated species of barley used in brewing? 1.2 Biochemistry Of The Barley Grain 1.2.1 Composition of the grain The barley grain is the seed of the barley plant and is composed of several distinct layers. The outermost layer is the husk, which protects the grain and remains attached even after threshing. Beneath the husk lies the pericarp, a thin tissue that surrounds the endosperm. The endosperm is the largest portion of the grain and contains starch reserves that serve as the primary source of fermentable sugars during brewing. Embedded within the endosperm are proteins that influence the clarity and stability of beer. At the base of the grain lies the embryo, which is the living part of the seed responsible for germination.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Diagram of barley grain showing husk, pericarp, endosperm, and embryo. Figure 1.2: Structural composition of the barley grain Fill in the blank: The largest portion of the barley grain, which contains starch reserves, is called the __________. 1.2.2 Enzymatic constituents and their roles Within the barley grain, several enzymes play crucial roles during germination and malting. Enzymes are biological catalysts that speed up chemical reactions without being consumed in the process. The most important enzymes in barley include amylases, which break down starch into fermentable sugars, and proteases, which degrade proteins into smaller peptides and amino acids. These reactions are essential for producing wort that can be fermented by yeast. Another key group of enzymes are the beta-glucanases, which break down cell wall components called beta-glucans. This process improves the flow of wort during brewing. The balance and activity of these enzymes determine the efficiency of malt production and the quality of the final beer.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Box 1.1: Key enzymes in barley grain and their functions Fill in the blank: The enzyme responsible for breaking down starch into fermentable sugars is called __________. Pilot questions 1.2 1. Which part of the barley grain contains the starch reserves? 2. What is the role of the husk in the barley grain? 3. Name one enzyme that breaks down proteins in barley. 4. Which enzyme improves wort flow by breaking down cell wall components? 5. Why are enzymes considered biological catalysts? 1.3 Barley Varieties And Classification 1.3.1 Nature of barley varieties Barley exists in several varieties, each adapted to specific climates, soil conditions, and brewing requirements. The two most common types are two-row barley and six-row barley. In two-row barley, the spike produces two rows of grains, resulting in larger kernels with higher starch content. Six-row barley, on the other hand, produces six rows of grains, which are smaller but richer in protein. Brewers often prefer two-row barley for its higher extract yield and cleaner flavour profile, while six-row barley is valued for its enzyme strength, which supports the use of adjuncts in brewing. The
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS choice of variety therefore depends on the brewing style and the desired characteristics of the beer. Photograph comparing two-row and six-row barley spikes. Plate 1.2: Comparison of two-row and six-row barley varieties Fill in the blank: The barley variety with higher starch content and larger kernels is __________ barley. 1.3.2 Classification systems Barley can be classified in several ways, including by row number, growth habit, and end-use quality. The row number classification distinguishes between two-row and six-row types, as discussed earlier. Growth habit classification separates winter barley, which is sown in autumn and harvested in summer, from spring barley, which is sown in spring and harvested later in the same year. End-use classification is particularly important in brewing. Malting barley varieties are selected for their high starch content, low protein levels, and favourable enzyme activity. These qualities make them ideal for producing malt that yields fermentable sugars and contributes positively to beer flavour. In contrast, feed barley varieties are grown primarily for animal consumption and are not suitable for brewing.
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