BST322 — Fermentation Technology: Lecture Note

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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: BST322 • Course title: Fermentation Technology • Course credit load: 3 Series 1: Principles and Objectives of Fermentation Suggested Outline Part 1: Foundations of Fermentation • 1.1 Definition and Scope of Fermentation • 1.2 Historical and Industrial Importance • 1.3 Objectives of Fermentation in Brewing Part 2: Scientific Principles of Fermentation • 1.2.1 Microbial Basis of Fermentation • 1.2.2 Biochemical Pathways (overview of glycolysis and conversion of wort to beer) • 1.2.3 Environmental Factors Influencing Fermentation Part 3: Fermentation in Brewing Practice • 1.3.1 Wort Preparation and its Role • 1.3.2 Fermentation Vessels and Brewery Layout • 1.3.3 Control and Regulation of Fermentation Part 4: Objectives and Outcomes of Beer Fermentation • 1.4.1 Desired Products and By-products • 1.4.2 Quality and Stability Considerations • 1.4.3 Linking Fermentation Objectives to Commercial Brewing Introduction

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Fermentation has been central to human civilisation for centuries, shaping the production of bread, wine, and beer. In brewing, fermentation is not only a biological process but also a carefully managed technological operation that transforms wort into beer. Understanding the principles and objectives of fermentation provides the foundation for mastering the rest of this course, since it connects scientific theory with practical brewing outcomes. The aim of this Series is to introduce you to the fundamental principles and objectives of fermentation, equipping you with the knowledge to appreciate its scientific basis and practical significance in brewing. We shall commence this Series by exploring the foundations of fermentation, including its definition, scope, and objectives. Next, we will examine the scientific principles that underpin fermentation, focusing on microbial activity, biochemical pathways, and environmental influences. Following that, we will consider fermentation in brewing practice, looking at wort preparation, fermentation vessels, and regulatory control. Finally, we will conclude by discussing the objectives and outcomes of beer fermentation, linking them to product quality and commercial brewing success. Series Learning Outcomes Upon completing this Series, you should be able to: • SLO 1.1 define fermentation and explain its scope and objectives in brewing, • SLO 1.2 describe the microbial and biochemical principles that underpin fermentation, • SLO 1.3 analyse the role of wort preparation, vessels, and brewery layout in fermentation practice, and • SLO 1.4 evaluate the objectives and outcomes of beer fermentation in relation to product quality and stability. 1.1 Definition And Scope Of Fermentation Fermentation is a biological process in which microorganisms such as yeast convert sugars into alcohol, carbon dioxide, and other by-products. The term fermentation refers to the metabolic activity of these organisms under anaerobic conditions, meaning in the absence of oxygen. In brewing, fermentation is the central stage that transforms wort, a sugar-rich liquid derived from malted grains, into beer. This process is not only a scientific phenomenon but also a technological operation that requires careful control. It is the bridge between raw materials and the finished product. Fill in the blank: Fermentation occurs under ______ conditions, where oxygen is absent.

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Diagram showing yeast converting sugars into alcohol and carbon dioxide Caption: Figure 1.1 Fermentation process overview 1.1.1 Historical And Industrial Importance Fermentation has been used for centuries in food and beverage production. Ancient civilisations relied on natural fermentation to produce bread, wine, and beer. In modern times, fermentation has become a controlled industrial process, ensuring consistency, safety, and quality. In brewing, fermentation is both an art and a science. Brewers must balance tradition with technology to achieve desired flavours and stability. The industrial importance of fermentation lies in its ability to produce beverages at commercial scale while maintaining product quality. Fill in the blank: Ancient civilisations used fermentation to produce ______, wine, and beer.

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Image of traditional beer brewing in ancient vessels Caption: Plate 1.1 Traditional brewing practices 1.1.2 Objectives Of Fermentation In Brewing The objectives of fermentation in brewing are multifaceted. Firstly, it aims to produce alcohol and carbon dioxide, which are essential for beer’s character. Secondly, fermentation generates flavour compounds such as esters and phenols that contribute to the sensory profile of beer. Thirdly, it ensures product stability by reducing residual sugars that could otherwise spoil the beverage. The brewer’s goal is to achieve a balance between alcohol content, flavour complexity, and stability. This requires precise control of yeast activity and environmental conditions. Fill in the blank: One objective of fermentation is to produce flavour compounds such as ______ and phenols. Box 1.1: Objectives of fermentation in brewing • Production of alcohol and carbon dioxide: Converts fermentable sugars into ethanol to establish the desired alcohol-by-volume (ABV) and generates natural carbonation for mouthfeel and head retention. • Generation of flavour compounds: Synthesizes key secondary metabolites such as esters, higher alcohols, and phenols that define the distinct aromatic and taste profile of the beer style. • Assurance of product stability: Lowers pH and depletes dissolved oxygen through active yeast metabolism, enhancing microbial shelf-life and colloidal stability.

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Pilot questions 1.1 1. Fermentation occurs under which type of conditions? 2. Name two products of yeast fermentation. 3. What did ancient civilisations use fermentation to produce? 4. State one industrial importance of fermentation in brewing. 5. Identify one objective of fermentation in brewing. 1.2 Scientific Principles Of Fermentation 1.2.1 Microbial Basis Of Fermentation Fermentation is driven by microorganisms, primarily yeast. Yeast is a unicellular fungus that metabolises sugars to produce alcohol and carbon dioxide. In brewing, the most common species used is Saccharomyces cerevisiae, valued for its efficiency and flavour contributions. The microbial basis of fermentation lies in the ability of yeast to thrive in sugar-rich environments and convert these sugars into products that define beer. Fill in the blank: The most common yeast species used in brewing is Saccharomyces ______. Diagram showing yeast cells consuming sugars and releasing alcohol and carbon dioxide Caption: Figure 1.2 Yeast activity in fermentation 1.2.2 Biochemical Pathways

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS The biochemical foundation of fermentation is glycolysis, a metabolic pathway where glucose is broken down into pyruvate. Under anaerobic conditions, pyruvate is converted into ethanol and carbon dioxide. This process releases energy that sustains yeast growth and activity. Fermentation also produces secondary metabolites such as esters, higher alcohols, and organic acids. These compounds contribute to the flavour and aroma of beer. Brewers must manage conditions carefully to encourage desirable by-products while minimising unwanted ones. Fill in the blank: The metabolic pathway that breaks down glucose into pyruvate is called ______. Box 1.2: Key biochemical products of fermentation • Ethanol: The primary alcohol produced by yeast metabolism, determining the overall alcohol-by-volume (ABV) and body of the beer. • Carbon dioxide: Natural gas generated alongside ethanol, utilized for carbonation, purging oxygen, and creating foam stability. • Esters: Aromatic volatile compounds synthesized from organic acids and alcohols, responsible for fruity aromas such as apple, banana, and pear. • Higher alcohols: Complex alcohols (fusel alcohols) produced during amino acid metabolism that contribute warmth and complex background flavor notes. • Organic acids: Metabolic byproducts such as lactic and acetic acid that subtly lower pH, influencing tartness and overall flavor balance. 1.2.3 Environmental Factors Influencing Fermentation Fermentation efficiency and outcomes depend on environmental factors such as temperature, pH, oxygen availability, and nutrient levels. For example, higher temperatures may accelerate fermentation but risk producing off-flavours, while lower temperatures slow down yeast activity but enhance flavour stability. Brewers must monitor and adjust these factors to achieve consistent results. The balance between yeast physiology and environmental conditions determines the quality of the final beer. Fill in the blank: One environmental factor that influences fermentation outcomes is ______. Table 1.1: Environmental factors affecting fermentation

LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Factor Effect on fermentation Temperature Influences speed and flavour profile pH Affects yeast activity and stability Oxygen Impacts yeast growth and metabolism Nutrients Support yeast health and fermentation efficiency Pilot questions 1.2 1. Name the primary microorganism responsible for fermentation in brewing. 2. What is the metabolic pathway that breaks down glucose into pyruvate? 3. Identify one secondary metabolite produced during fermentation. 4. State one environmental factor that influences fermentation outcomes. 5. Why must brewers manage fermentation conditions carefully? 1.3 Fermentation In Brewing Practice 1.3.1 Wort Preparation And Its Role Wort is the sugar-rich liquid extracted from malted grains during the brewing process. It provides the essential nutrients required for yeast growth and fermentation. The composition of wort, including its sugar profile, amino acids, and minerals, directly influences the efficiency of fermentation and the flavour of the final beer. Brewers must ensure that wort is properly prepared, cooled, and aerated before yeast is pitched. This preparation sets the stage for successful fermentation. Fill in the

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