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This is the complete lecture note for FST 304 Principles of Food Analysis. 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: FST304 Course title: Principles of Food Analysis Course credit load: 3 units List of Series: 1. Physical and Chemical Transformations in Foods 2. Lipids and Proteins: Properties, Reactions, and Applications 3. Carbohydrates, Hydrocolloids, and Starch Modifications 4. Enzyme Systems and Browning Reactions in Food Quality 5. Vitamins, Natural Pigments, Flavours, and Additives in Foods 1. Physical Changes in Foods during Handling and Storage • 1.1 Moisture in Foods • 1.2 Free and Bound Water • 1.3 Hydrogen Bonding and its Role in Food Structure 2. Chemical Changes in Foods during Processing and Storage • 2.1 Lipid Changes: Auto-oxidation, Pro-oxidants, and Antioxidants • 2.2 Protein Changes: Denaturation and Gel Formation • 2.3 Carbohydrate Changes: Gelatinisation and Retrogradation 3. Measurement and Analysis of Food Changes • 3.1 Methods of Measuring Lipid Changes • 3.2 Methods of Assessing Protein Denaturation • 3.3 Techniques for Studying Carbohydrate Modifications 4. Implications of Physical and Chemical Changes on Food Quality • 4.1 Flavour Changes in Foods • 4.2 Texture and Structural Modifications • 4.3 Nutritional and Safety Considerations Introduction
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Food is never static. From the moment it is harvested or produced, it begins to undergo a variety of physical changes such as moisture loss and textural modifications, as well as chemical changes including oxidation and enzymatic reactions. These transformations are central to food quality, safety, and shelf life. For anyone studying food science, recognising how these changes occur during handling, processing, and storage is essential, since they directly influence flavour, texture, nutritional value, and consumer acceptance. This Series therefore sets the foundation for understanding the dynamic nature of foods and prepares you to analyse them with precision. The aim of this Series is to equip you with the knowledge and skills needed to explain, analyse, and evaluate the physical and chemical changes that foods undergo, and to relate these changes to food quality and measurement techniques. We shall commence this Series by examining the physical changes in foods during handling and storage, with particular attention to moisture, water states, and hydrogen bonding. Next, we will explore chemical changes that occur during processing and storage, focusing on lipids, proteins, and carbohydrates. Following that, we will consider methods of measurement and analysis that help us study these changes in detail. Finally, we will wrap up by discussing the implications of these transformations on food quality, including flavour, texture, nutrition, and safety. This sequential approach will enable you to build a clear and connected understanding of how foods evolve from production to consumption. Series Learning Outcomes Upon completing this Series, you should be able to: SLO 1.1 define the concept of physical changes in foods and explain the roles of moisture, water states, and hydrogen bonding during handling and storage, SLO 1.2 analyse the chemical changes that occur in lipids, proteins, and carbohydrates during processing and storage, SLO 1.3 demonstrate methods of measurement and analysis used to assess lipid oxidation, protein denaturation, and carbohydrate modifications, SLO 1.4 evaluate the implications of physical and chemical changes on food quality, including flavour, texture, nutrition, and safety. 1.1 Physical Changes in Foods During Handling and Storage Physical changes in foods are alterations that affect the structure, texture, and appearance of food without necessarily altering its chemical composition. These changes occur during handling, processing, and storage, and they are critical because they influence consumer acceptance and shelf life. Examples include moisture migration, crystallisation, and changes in firmness. By
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS studying these changes, you will be able to explain why foods behave differently under varying storage conditions and how these behaviours can be controlled. Fill in the blank: Physical changes in foods affect their ________, texture, and appearance without altering chemical composition. 1.1.1 Moisture in foods Moisture refers to the amount of water present in food. It plays a vital role in determining food quality, safety, and stability. Foods with high moisture content, such as fruits and vegetables, are more prone to microbial spoilage, while low-moisture foods, such as grains, are more stable but can suffer from textural changes. Moisture can be classified into free water, which is available for microbial growth and chemical reactions, and bound water, which is tightly associated with food molecules and less available for reactions. Figure 1.1 Distribution of free and bound water in food. Fill in the blank: ________ water is available for microbial growth, while ________ water is tightly associated with food molecules. 1.1.2 Free and bound water Free water is water that is not chemically bound to food components and can move freely within the food matrix. It supports microbial growth and enzymatic activity. Bound water is water that
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS is held tightly by proteins, carbohydrates, or other molecules, making it unavailable for microbial growth. The ratio of free to bound water determines the stability of food during storage. Table 1.1 Characteristics of free and bound water in foods. Fill in the blank: The ratio of free to bound water determines the ________ of food during storage. 1.1.3 Hydrogen bonding and its role in food structure Hydrogen bonding is the attraction between a hydrogen atom and an electronegative atom such as oxygen or nitrogen. In foods, hydrogen bonding plays a crucial role in stabilising structures such as proteins and carbohydrates. It influences water retention, texture, and the ability of foods to form gels. For example, hydrogen bonding helps starch granules retain water during gelatinisation, and it stabilises protein structures during processing.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Figure 1.2 Hydrogen bonding interactions in food molecules. Fill in the blank: Hydrogen bonding stabilises structures such as ________ and carbohydrates in foods. Pilot questions 1.1 1. Which type of water in foods is available for microbial growth? 2. What is the main difference between free water and bound water? 3. How does moisture content affect food stability? 4. What role does hydrogen bonding play in food texture? 5. Why are high-moisture foods more prone to spoilage than low-moisture foods? 1.2 Chemical Changes in Foods During Processing and Storage Chemical changes in foods occur when the molecular composition of food components is altered during handling, processing, or storage. These changes are often irreversible and can significantly affect flavour, texture, nutritional value, and safety. By studying chemical changes, you will be able to explain how lipids, proteins, and carbohydrates react under different conditions, and how these reactions influence food quality.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Fill in the blank: Chemical changes in foods involve alterations in their ________ composition, often leading to irreversible effects. 1.2.1 Lipid changes: auto-oxidation, pro-oxidants, and antioxidants Lipids are fats and oils that serve as important sources of energy and flavour in foods. One major chemical change in lipids is auto-oxidation, which is the spontaneous reaction of unsaturated fatty acids with oxygen, leading to rancidity and off-flavours. This process is accelerated by pro-oxidants, which are substances such as light, heat, and certain metals that promote oxidation. To counteract this, antioxidants are compounds that delay or prevent oxidation by stabilising free radicals. Figure 1.3 Auto-oxidation of lipids and the role of antioxidants. Fill in the blank: Substances such as light, heat, and metals that accelerate lipid oxidation are called ________. 1.2.2 Protein changes: denaturation and gel formation Proteins are large molecules made up of amino acids that provide structure and functionality in foods. Denaturation is the process by which proteins lose their natural structure due to heat, pH changes, or mechanical action. This change alters their solubility and functionality. One important consequence of denaturation is gel formation, where denatured proteins form a three-dimensional network that traps water, giving foods such as yoghurt and custard their characteristic texture.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Plate 1.1 Gel formation in protein-based foods. Fill in the blank: The process by which proteins lose their natural structure due to heat or pH changes is called ________. 1.2.3 Carbohydrate changes: gelatinisation and retrogradation Carbohydrates are sugars and starches that provide energy and contribute to texture in foods. Gelatinisation is the process where starch granules absorb water and swell upon heating, leading to thickening of foods such as sauces and puddings. Retrogradation occurs when gelatinised starch molecules, particularly amylose, reassociate during cooling, resulting in firming or staling of foods like bread. These changes are important in determining the shelf life and textural quality of carbohydrate-rich foods.
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