Nigeria's free digital learning hub. Videos, lecture notes, practice questions and leaderboards aligned with CCMAS, NBTE, NCCE, WAEC, NECO, IJMB and JAMB curricula.
Loading
Nigeria's free digital learning hub. Videos, lecture notes, practice questions and leaderboards aligned with CCMAS, NBTE, NCCE, WAEC, NECO, IJMB and JAMB curricula.
This is the complete lecture note for FST303 Food Process Engineering. 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: FST 303 • Course title: Food Process Engineering • Course credit load: 2 Series 1: Thermophysical Properties of Food Series outline • 1.1 Glossary of Thermophysical Properties o 1.1.1 Definition and scope o 1.1.2 Key categories of properties o 1.1.3 Importance in food processing • 1.2 Methods of Determination o 1.2.1 Experimental techniques o 1.2.2 Instrumentation and measurement tools o 1.2.3 Limitations and accuracy considerations • 1.3 Relevance to Food Processing o 1.3.1 Role in heat transfer and mass transfer o 1.3.2 Influence on equipment design and operation o 1.3.3 Case examples in thermal processing • 1.4 Food Composition versus Thermophysical Properties o 1.4.1 Relationship between composition and properties o 1.4.2 Variations across food categories o 1.4.3 Practical implications for engineers Introduction Food processing often involves the transfer of heat and mass, both of which depend heavily on the physical characteristics of the food material. These characteristics, known as thermophysical properties, determine how foods respond to heating, cooling, freezing, and drying. For instance, the way milk boils or the way bread bakes is influenced by these properties. By studying them, food
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS engineers can design safer, more efficient, and more consistent processes. This Series therefore provides the foundation for understanding how food behaves under different processing conditions, making it essential for the rest of the course. The aim of this Series is to equip you with the ability to define, measure, and analyse the thermophysical properties of food, and to evaluate their relevance in food processing operations. We shall commence this Series by examining the glossary of thermophysical properties, where you will learn their definitions and categories. Next, we will move on to methods of determination, focusing on experimental techniques and measurement tools. Following that, we will explore their relevance to food processing, considering how they affect heat transfer, equipment design, and practical applications. Finally, we will wrap up by analysing the relationship between food composition and thermophysical properties, highlighting variations across food categories and their implications for engineers. Series Learning Outcomes Upon completing this Series, you should be able to: • SLO 1.1 define the glossary of thermophysical properties of food, • SLO 1.2 explain methods used to determine thermophysical properties, • SLO 1.3 analyse the relevance of thermophysical properties in food processing operations, and • SLO 1.4 evaluate the relationship between food composition and thermophysical properties. 1.1 Glossary Of Thermophysical Properties 1.1.1 Definition and scope The term thermophysical properties refers to the physical characteristics of food materials that influence how they respond to heat and mass transfer. These include properties such as thermal conductivity, specific heat, density, and viscosity. They are essential because they determine how food behaves during processes like heating, cooling, freezing, and drying. Without accurate knowledge of these properties, engineers cannot design reliable food processing systems. Fill in the blank: The property that describes how easily heat passes through a food material is called __________.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Diagram showing heat transfer through different food materials Figure 1.1: Illustration of heat transfer in foods 1.1.2 Key categories of properties The main categories of thermophysical properties include: • Thermal conductivity: the ability of a food material to conduct heat. • Specific heat capacity: the amount of heat required to raise the temperature of a unit mass of food by one degree Celsius. • Density: the mass per unit volume of food, which affects both heat and mass transfer. • Viscosity: the resistance of a fluid food to flow, which influences pumping and mixing operations. Each of these properties varies depending on the composition of the food, such as its water, fat, protein, and carbohydrate content. For example, foods with high water content generally have higher specific heat values. Fill in the blank: The resistance of a fluid food to flow is referred to as __________. Comparison of selected thermophysical properties of common foods Table 1.1: Typical values of thermophysical properties in foods
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Food Material Thermal Conductivity (W/m⋅K) Specific Heat (kJ/kg⋅K) Density (kg/m3) Viscosity (Pa⋅s) Milk (Whole) ~ 0.55 - 0.60 ~ 3.85 - 3.95 ~ 1028 - 1035 ~ 0.0015 - 0.0025 Bread (White) ~ 0.06 - 0.20 ~ 2.40 - 2.90 ~ 200 - 300 Not applicable (Solid) Meat (Beef, Lean) ~ 0.40 - 0.55 ~ 3.30 - 3.60 ~ 1040 - 1080 Not applicable (Solid) 1.1.3 Importance in food processing Thermophysical properties are crucial in designing and controlling food processing operations. For instance, thermal conductivity determines how quickly heat penetrates canned foods during sterilisation, while viscosity affects the efficiency of pumping tomato paste through pipelines. Engineers must consider these properties to ensure food safety, quality, and energy efficiency. Fill in the blank: During sterilisation of canned foods, the property that determines how quickly heat penetrates is __________. Box 1.1: Case study – Tomato paste processing Description: Tomato paste has high viscosity, which requires specialised pumps and careful heat transfer calculations to avoid uneven heating. Description: Tomato paste has high viscosity, which requires specialised pumps and careful heat transfer calculations to avoid uneven heating. Processing Challenges: * Flow and Transport: Because of its thickness, standard pumps may fail. Specialised equipment like rotary lobe pumps or piston pumps are needed to move the paste without damaging it (shearing). * Heat Transfer: Standard heat exchangers (like plate-and-frame) may plug or lead to burning if the paste moves too slowly. Specialised heat exchangers, such as scraped surface or double-pipe systems, must be used to ensure uniform heating.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS * Mixing: Achieving homogeneous mixing becomes difficult with high-viscosity materials, requiring high-torque mixers and carefully designed agitation systems. Food Engineering Impact: The entire system must be designed based on non-Newtonian fluid dynamics to maintain product quality and process efficiency. Pilot questions 1.1 1. Which property describes the amount of heat required to raise the temperature of a unit mass of food by one degree Celsius? 2. What is the term used for the mass per unit volume of food? 3. Which property influences the efficiency of pumping operations in fluid foods? 4. Why are thermophysical properties important in food processing operations? 5. Give one example of how food composition affects thermophysical properties. 1.2 Methods Of Determination 1.2.1 Experimental techniques To measure thermophysical properties, food engineers rely on carefully designed experiments. For example, thermal conductivity can be determined using methods such as the line heat source technique, where a heated probe is inserted into the food and the rate of heat transfer is measured. Similarly, specific heat capacity is often measured using calorimetry, which involves heating a known mass of food and recording the temperature change. These experiments must be conducted under controlled conditions to ensure accuracy. Fill in the blank: The method commonly used to measure specific heat capacity in foods is __________.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Diagram showing calorimetry setup for measuring specific heat capacity Figure 1.2: Calorimetry experiment for food samples 1.2.2 Instrumentation and measurement tools Accurate measurement of thermophysical properties requires specialised instruments. For instance, a viscometer is used to measure viscosity, while a pycnometer is employed to determine density. Advanced tools such as differential scanning calorimeters are used to study heat flow in foods during phase changes like melting or freezing. These instruments provide precise data that can be applied in designing food processing equipment. Fill in the blank: The instrument used to measure viscosity in fluid foods is called a __________.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS ] Image of a viscometer used in food laboratories Plate 1.1: Laboratory viscometer for measuring viscosity 1.2.3 Limitations and accuracy considerations While these methods and instruments are effective, they are not without limitations. Food materials are often heterogeneous, meaning their composition varies across samples. This can lead to inconsistencies in measurements. Additionally, temperature and moisture content can significantly affect results. Engineers must therefore interpret data carefully, often repeating experiments to confirm reliability. Fill in the blank: One major challenge in measuring thermophysical properties of food is its __________ nature.
This is the opening of the note. Read the full note or download the PDF to continue.
