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This is the complete lecture note for FST403 Fruits and Vegetables Technology. 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 403 • Course title: Fruits and Vegetables Technology • Course credit load: 3 Series 1: Handling and Processing of Fresh Produce Series outline • 1.1 Principles of Handling Fresh Produce o 1.1.1 Post-harvest physiology o 1.1.2 Factors affecting quality • 1.2 Chemical Control of Changes o 1.2.1 Enzymic changes o 1.2.2 Non-enzymic changes • 1.3 Grading, Sorting and Cleaning o 1.3.1 Grading standards o 1.3.2 Sorting technologies o 1.3.3 Cleaning methods • 1.4 Peeling, Sampling and Size Reduction o 1.4.1 Peeling techniques o 1.4.2 Sampling procedures o 1.4.3 Size reduction methods Introduction Fresh fruits and vegetables are among the most perishable commodities in the food industry, and their quality can deteriorate rapidly if not handled properly. Imagine a basket of ripe tomatoes left in the sun for a few hours: the colour fades, the texture softens, and the flavour diminishes. This simple scenario highlights why careful handling and processing are essential, not only to maintain nutritional value but also to ensure consumer satisfaction and reduce waste. Within the broader course on Fruits and Vegetables Technology, this Series lays the foundation by focusing on the initial stages of post-harvest management.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS The aim of this Series is to equip you with the knowledge and skills required to handle fresh produce effectively, control chemical changes, and apply appropriate techniques for grading, sorting, cleaning, peeling, sampling, and size reduction. We shall commence this Series by examining the principles of handling fresh produce, including post-harvest physiology and the factors that influence quality. Next, we will explore the chemical control of enzymic and non-enzymic changes that affect freshness and shelf life. Following that, we will study the processes of grading, sorting, and cleaning, which are vital for preparing produce for further processing. Finally, we will wrap up by considering peeling, sampling, and size reduction methods, which are crucial steps in preparing fruits and vegetables for industrial applications. Series Learning Outcomes Upon completing this Series, you should be able to: • SLO 1.1 define post-harvest physiology and explain its relevance to the handling of fresh produce, • SLO 1.2 analyse the factors that affect the quality of fruits and vegetables during handling, • SLO 1.3 describe enzymic and non-enzymic changes and demonstrate methods of chemical control, • SLO 1.4 explain grading standards and apply sorting and cleaning techniques to fresh produce, • SLO 1.5 evaluate peeling techniques and sampling procedures, and • SLO 1.6 demonstrate methods of size reduction for fruits and vegetables in processing operations. 1.1 Principles of Handling Fresh Produce 1.1.1 Post-harvest physiology Fresh fruits and vegetables remain biologically active even after harvest. Post-harvest physiology is the study of the biological processes that continue in produce once it has been detached from the parent plant. These processes include respiration (the breakdown of sugars to release energy), transpiration (loss of water vapour), and ethylene production (release of a natural plant hormone that accelerates ripening). Each of these influences the shelf life, flavour, texture, and nutritional value of produce. For instance, bananas ripen quickly due to high ethylene production, while leafy vegetables wilt rapidly because of excessive transpiration. Fill in the blank: The natural plant hormone that accelerates ripening in fruits is _______.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Diagram showing respiration, transpiration, and ethylene production in harvested fruits. Figure 1.1: Biological processes in post-harvest physiology 1.1.2 Factors affecting quality Several external factors determine the quality of fresh produce during handling. Temperature is critical, as higher temperatures increase respiration rates and shorten shelf life. Humidity also plays a role: low humidity causes wilting, while excessive humidity encourages microbial growth. Mechanical damage such as bruising during transport reduces market value and increases susceptibility to decay. Finally, microbial contamination can occur when produce is exposed to unsanitary conditions, leading to spoilage and food safety concerns. Fill in the blank: When vegetables are stored in conditions of low humidity, they are likely to _______.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Image of bruised apples showing mechanical damage during handling. Plate 1.1: Mechanical damage in fresh produce Pilot questions 1.1 1. What is meant by post-harvest physiology? 2. Which biological process involves the breakdown of sugars to release energy in harvested produce? 3. What natural plant hormone accelerates ripening in fruits? 4. How does high temperature affect the respiration rate of fresh produce? 5. What is one consequence of low humidity during storage of vegetables? 1.2 Chemical Control of Changes 1.2.1 Enzymic changes Fresh fruits and vegetables undergo enzymic changes, which are chemical reactions catalysed by enzymes naturally present in plant tissues. Enzymes are biological catalysts that speed up reactions without being consumed. In produce, enzymes such as polyphenol oxidase cause browning when tissues are cut or bruised, while pectinase softens fruit texture during ripening. These changes can reduce consumer appeal and shorten shelf life. To control enzymic activity, processors use methods such as blanching, chemical inhibitors, or modified storage conditions. Fill in the blank: The enzyme responsible for browning in cut apples is _______.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Diagram showing enzymic browning in apples and its prevention by blanching. Figure 1.2: Enzymic browning and control methods 1.2.2 Non-enzymic changes In addition to enzymic activity, fruits and vegetables also experience non-enzymic changes, which are chemical reactions not driven by enzymes. A common example is the Maillard reaction, where reducing sugars react with amino acids to produce brown pigments and flavour compounds. Another example is oxidation, where exposure to oxygen leads to colour and nutrient loss. These changes can occur during handling, storage, or processing, and they influence both the nutritional and sensory qualities of produce. Control measures include reducing oxygen exposure, using antioxidants, and maintaining appropriate storage conditions. Fill in the blank: The reaction between reducing sugars and amino acids that produces brown pigments is called _______.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Box 1.1: Key differences between enzymic and non-enzymic changes • Enzymic changes: catalysed by enzymes, e.g., browning by polyphenol oxidase. • Non-enzymic changes: occur without enzymes, e.g., Maillard reaction and oxidation. Pilot questions 1.2 1. What are enzymes and how do they affect fresh produce? 2. Which enzyme causes browning in cut apples? 3. What is the Maillard reaction and why is it significant in food processing? 4. How does oxidation affect the nutritional quality of fruits and vegetables? 5. Name one method used to control enzymic changes in fresh produce. 1.3 Grading, Sorting and Cleaning 1.3.1 Grading standards Grading refers to the classification of fruits and vegetables based on specific quality parameters such as size, colour, shape, and absence of defects. Grading standards are guidelines established to ensure uniformity and consistency in produce quality. For example, citrus fruits may be graded according to diameter and skin colour, while tomatoes are graded based on ripeness and firmness. Grading helps processors and retailers meet consumer expectations and comply with regulatory requirements.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Fill in the blank: Fruits and vegetables are classified into categories based on _______. Table 1.1: Examples of grading standards for selected fruits and vegetables 1.3.2 Sorting technologies Sorting is the process of separating produce into groups according to specific attributes. Traditional sorting methods rely on manual inspection, while modern systems use mechanical or electronic technologies. Mechanical sorting may involve sieves or rollers that separate produce by size, whereas electronic sorting uses sensors to detect colour, weight, or defects. Automated sorting improves efficiency, reduces labour costs, and ensures greater accuracy. Fill in the blank: Modern sorting systems often use _______ to detect colour and defects in produce.
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