POST-HARVEST LOSSES IN VEGETABLES

October 30, 2023

Post-harvest losses in vegetables are a significant issue that affects farmers, consumers, and the overall food supply chain. These losses occur due to various factors and can have a detrimental impact on food security, economic growth, and environmental sustainability. Therefore, effective management of post-harvest losses is crucial to mitigate these negative consequences and ensure a sustainable vegetable production system.

Post-harvest losses in vegetables occur at various stages of the supply chain. Starting from the moment you harvest vegetables until they reach the consumer’s plate. The primary causes of these losses include: physiological, pathological, and physical.

Physiological Factors: Post-Harvest Losses in Vegetables

Physiological factors refer to the natural processes that continue within vegetables after harvest. For instance, vegetables respire, which means they continue to breathe even after harvesting. This respiration leads to a loss of moisture and nutrients, causing wilting, softening, and spoilage. Moreover, vegetables can undergo other physiological changes such as color changes, ripening, and senescence. This can further contribute to post-harvest losses in vegetables.

Pathological factors

Pathological factors involve the attack of microorganisms, pests, and diseases on vegetables after harvest. Bacteria, fungi, viruses, insects, and rodents can all cause significant damage to vegetables and result in high losses. These pathogens can infect vegetables during cultivation or during harvesting, handling, and transportation. Once infected, vegetables become susceptible to rotting, mold growth, and decay. Furthermore, some pathogens can produce toxins that not only affect the quality of vegetables. They also pose health risks to consumers.

Physical Factors

Physical factors encompass all the mechanical and environmental factors that vegetables encounter in the post-harvest stage. Improper handling, such as rough handling, excessive loading, or inadequate packaging, leads to physical damages like bruises, cuts, or abrasions. These damages not only affect the appearance and consumer acceptability of vegetables but also provide entry points for microbial contamination. Environmental factors such as temperature, humidity, and light also influence vegetable quality. If you store and transport vegetables under unfavourable conditions, they can deteriorate rapidly and result in significant losses.

1. Tomatoes.

Tomatoes are one of the most widely grown and consumed vegetables globally. However, post-harvest losses in tomato production can be a significant problem for farmers, leading to decreased profits and wasted resources. Efficient management practices are crucial to minimise these losses, starting from simple to complex systems of management.

At the simplest level, reducing post-harvest losses in tomatoes is through proper harvesting techniques. This includes picking fully ripe or near-ripe tomatoes, as they are less prone to damage during transportation and storage. Proper care helps not to bruise or damage the tomatoes during picking. Any injury can lead to increased rates of spoilage and rotting.

Once you harvest, sort tomatoes for quality. This involves removing damaged or overripe tomatoes that are more prone to spoilage. Sorting is manual or with the help of simple machinery such as a conveyor belt or sorting table.

Proper packaging is another important aspect of post-harvest management. Packaging should be clean and sturdy, providing protection against physical damage and reducing the risk of bruising. Appropriate packaging materials, such as plastic crates or foam padding, can help prevent excessive pressure and impact during transportation.

Temperature regulation storage.

Post-harvest loss is a major challenge in the agricultural industry. The perishable nature of many fruits and vegetables makes it difficult for farmers to preserve their produce after harvesting. This results in financial losses and food waste. One method that has proven effective in managing post-harvest losses is refrigeration storage, particularly for tomatoes.

Tomatoes are highly perishable fruits that have a relatively short shelf life. Without proper storage conditions, they can quickly deteriorate, leading to a significant amount of wastage. Refrigeration storage provides an optimal environment for extending the shelf life of tomatoes and reducing post-harvest losses.

Benefits of refrigeration

One of the primary benefits of refrigeration storage for tomatoes is its ability to slow down the ripening process. Tomatoes continue to ripen after harvesting, and this process accelerates at higher temperatures. By storing tomatoes in refrigerated environments, the rate of ripening significantly slows down. This allows farmers and distributors to preserve the quality and freshness of the tomatoes for a longer period,. Reducing the chances of spoilage and wastage.

Another advantage of refrigeration storage is its ability to inhibit the growth of spoilage-causing microorganisms. Low temperatures slow down the metabolic activities of microorganisms, including bacteria and fungi, which are responsible for the decay of fruits and vegetables. By storing tomatoes in refrigerators, the growth of these microorganisms is easy to control, reducing the chances of spoilage. And extending the shelf life of the produce.

Additionally, refrigeration storage helps to maintain the nutritional value of tomatoes. Many vitamins and other nutrients are temperature-sensitive and can degrade rapidly under unfavourable conditions. By keeping tomatoes at low temperatures, you preserve their nutrients. It ensures that the consumer receives the maximum nutritional value from the fruit.

However, it is important to note that not all tomatoes you can be store in refrigerators. Some varieties, particularly those that are more sensitive to chilling injury, may experience adverse effects when subjected to low temperatures. Chilling injury can manifest as browning, softening, and loss of flavour. Therefore, farmers and distributors must understand the specific requirements of the tomato variety they are dealing with. This ensures proper storage conditions.

Post-harvest heat treatment.

Post-harvest heat treatment of tomatoes is an essential process to ensure the quality and safety of these popular fruits. Heat treatment, usually done through hot water immersion or steam treatment helps maintain firmness. This prolongs shelf life, and reduces the risk of microbial contamination.

Tomatoes are highly perishable due to their high water content, delicate skin, and susceptibility to diseases and decay. To mitigate these issues and preserve the freshness of tomatoes for an extended period, post-harvest heat treatment plays a crucial role.

One of the most widely used methods for post-harvest heat treatment is hot water immersion. In this process, you subject ripe tomatoes to a hot water bath set at a specific temperature for a predetermined duration. The temperature and time depend on the variety of tomatoes, the intended use, and the desired outcome. Generally, tomatoes are immersed in hot water ranging from 45 to 56 degrees Celsius for 1 to 5 minutes.

methods used in Post-harvest heat treatment.

Hot water treatment improves the quality of tomatoes by inducing heat shock proteins, which increase their ability to cope with stress and extend their shelf life. It also helps in preventing the onset of ripening, thereby maintaining the firmness and color of tomatoes. Additionally, hot water treatment can destroy or control the growth of certain pathogens, such as bacteria and fungi, reducing the chances of post-harvest diseases.

Similar to hot water treatment, steam treatment is gaining popularity as an alternative method for post-harvest heat treatment of tomatoes. It involves subjecting the fruits to high-temperature steam in a controlled environment. This treatment not only improves the fruit quality but also reduces moisture loss and fungal decay during storage.

Post-harvest heat treatment can also aid in reducing pests and insect infestation through the elimination of eggs or larvae present on the tomato’s surface. The controlled application of heat destroys these unwanted organisms, ensuring a safe and healthy product for consumers.

It is important to note that the treatment conditions and duration should be carefully monitored to avoid undesirable effects on the sensory qualities of tomatoes. Over-treatment can lead to a loss of flavor, texture, and nutritional value. Therefore, finding the optimal balance is crucial to maintaining the desired attributes of tomatoes while extending their shelf life.

Post-harvest heat treatment of tomatoes is widely practised in commercial settings such as food processing plants and packing houses. It allows for the preservation of tomatoes during transportation, storage, and distribution processes. This treatment method enhances the overall quality, safety, and market value of tomatoes, benefiting both producers and consumers.

Modified atmosphere packaging in Post-harvest management of tomatoes.

Modified atmosphere packaging (MAP) has become an essential tool in the post-harvest management of tomatoes. It is a packaging technique that involves altering the atmosphere surrounding the produce to increase shelf life, maintain freshness, and reduce microbial growth. The process removes oxygen and supplements beneficial gases to create an optimal environment for the tomatoes.

modified packaging material to reduce post-harvest losses in vegetables. photo credit.

In traditional packaging methods, such as using polyethylene bags or boxes, tomatoes are exposed to ambient air, which contains high levels of oxygen. However, oxidative reactions lead to faster ripening and spoilage of the fruit. By modifying the atmosphere within the package, the metabolic rate of the tomatoes is controlled, extending their shelf life and preserving their quality.

Types of gases used in MAP

The main gases used in MAP are carbon dioxide (CO2), nitrogen (N2), and oxygen (O2). Carbon dioxide inhibits the growth of spoilage organisms and decay-inducing enzymes, reducing microbial activity. Nitrogen is used to displace oxygen, preventing spoilage caused by aerobic microbes. Oxygen levels are reduced to suppress respiration, thereby slowing down the ripening and senescence processes of the tomatoes.

The selection of the appropriate gas composition and packaging material is crucial for the success of modified atmosphere packaging. Different varieties of tomatoes may respond differently to the gas composition, temperature, and humidity levels. Packaging materials with high gas barrier properties, such as polyethylene terephthalate (PET), ethylene-vinyl alcohol (EVOH), or polypropylene (PP), are commonly used in MAP to prevent gas exchange between the package and the external environment.

Benefits of modified atmosphere packaging

The benefits of modified atmosphere packaging in post-harvest losses in vegetables management of tomatoes are numerous. Firstly, it allows for the extension of the shelf life, enabling longer transportation and storage periods. This is particularly important for exporting countries, as it facilitates the distribution of fresh and high-quality produce to distant markets. MAP also reduces post-harvest losses, as the controlled atmosphere slows down the natural ripening and decay processes, reducing wastage.

Furthermore, MAP enhances the visual appeal of tomatoes, as it helps in preserving their color, firmness, and flavor. Consumers are more likely to choose tomatoes that are visually appealing and have a longer shelf life. This not only satisfies consumer preferences but also benefits the growers and sellers by increasing marketability and profitability.

However, there are certain limitations and challenges associated with modified atmosphere packaging. One of the challenges is the need for critical control points during the packaging process to ensure optimal gas composition, humidity, and temperature. Additionally, the capital investment required for MAP technology may be a constraint for small-scale farmers and producers.

Calcium Chloride Application for Post-Harvest Losses Management in Tomatoes

Tomatoes are one of the most popular and widely consumed fruits globally. However, throughout the post-harvest process, tomatoes are highly susceptible to physiological disorders and microbial spoilage, leading to significant losses for farmers and suppliers. To mitigate these losses, the use of calcium chloride has emerged as an effective strategy for post-harvest losses in vegetables management in tomatoes.

Calcium chloride (CaCl2) is a salt commonly used in agriculture for various purposes, including its ability to prevent decay and extend the shelf life of fruits and vegetables. When applied to tomatoes, it has been found to enhance their quality, improve firmness, reduce internal disorders, and inhibit the growth of spoilage-causing microorganisms.

Benefits of using calcium chloride in tomatoes

One of the primary benefits of calcium chloride application in tomatoes is its ability to reduce the occurrence and severity of physiological disorders, such as blossom end rot. Blossom end rot is a common disorder characterized by water-soaked lesions at the blossom end of the fruit, leading to tissue decay. This disorder occurs due to calcium deficiency, which can be prevented by applying calcium chloride to increase the calcium content in tomatoes. By maintaining proper calcium levels, blossom end rot can be significantly reduced, resulting in a higher yield of marketable tomatoes thus reducing post-harvest losses in vegetables.

In addition to preventing physiological disorders, the application of calcium chloride also plays a crucial role in inhibiting the growth of spoilage-causing microorganisms. Tomatoes are highly prone to microbial spoilage due to their high moisture content and delicate skin. This can result in the development of mold, mildew, and decay, rendering the fruits unsuitable for consumption. Calcium chloride acts as a natural preservative by creating an unfavorable environment for microbial growth, thereby extending the shelf life of tomatoes and reducing post-harvest losses.

Moreover, calcium chloride application enhances the firmness and texture of tomatoes, which is an essential quality parameter for consumers. The firmness of tomatoes is critical for transportation, handling, and processing purposes. By strengthening the cell walls, calcium ions from calcium chloride help maintain the structural integrity of tomatoes, reducing the incidence of bruises and damage during post-harvest operations.

How to use calcium chloride for minimising post harvest losses

To apply calcium chloride to tomatoes, various methods can be employed, including pre-harvest foliar spray, post-harvest dipping, or steam treatment. Pre-harvest foliar spray involves spraying a calcium chloride solution on the tomato plants during the growing season, allowing the plants to absorb and distribute calcium throughout their tissues. This method ensures that the tomatoes acquire a sufficient amount of calcium during their development, making them less prone to disorders post-harvest. Post-harvest dipping involves immersing the tomatoes in a calcium chloride solution for a specified duration to improve their resilience and shelf life. Steam treatment is another technique that helps in the application of calcium chloride by creating a controlled steam environment, making the fruit more permeable and receptive to calcium.

Methylcyclopropene application on tomatoes for Post-harvest losses management

Methylcyclopropene (MCP) is a chemical compound that has gained significant attention in recent years for its application in reducing post-harvest losses in tomatoes. Post-harvest losses refer to the deterioration of quality and subsequent spoilage that occurs after harvesting and during storage and transportation.

Tomatoes are highly perishable fruits that are prone to physiological changes such as ripening and softening, making them more susceptible to bruising, decay, and loss of shelf life. Farmers and suppliers have long struggled to find effective methods to prolong the freshness and quality of tomatoes, thereby reducing post-harvest losses.

MCP addresses this challenge by inhibiting the action of ethylene, a natural plant hormone responsible for ripening, which consequently leads to the decay and spoilage of fruits. By blocking ethylene receptors, MCP effectively slows down the ripening process, allowing tomatoes to retain their quality, texture, and appearance for a longer duration.

Application time for MCP

The application of MCP on tomatoes is typically done during the post-harvest stage, either as a pre-harvest coating or as a post-harvest dip. The compound is relatively easy to apply and does not leave any harmful residues on the fruit or affect its taste and nutritional value.

Studies show significant improvements in the shelf life and quality of tomatoes treated with MCP. The compound has been found to reduce the occurrence of softening, decay, and color changes in the fruit, thereby extending its marketability and reducing post-harvest losses. In addition, MCP treatment can also reduce the need for refrigeration and cold storage, saving energy and costs for farmers and suppliers.

Reasons for MCP Gaining Popularity

Using MCP in tomatoes has garnered interest from various stakeholders in the agricultural and supply chain industry due to its potential economic and environmental benefits. By minimizing post-harvest losses, both producers and consumers benefit from a more efficient and sustainable food system.

While MCP shows promising results, it is important for farmers and suppliers to follow proper guidelines and recommendations for its application. Furthermore, more research is needed to fully understand the long-term effects of MCP on tomatoes and its potential impact on human health, the environment, and post-harvest losses in vegetables.

Implementation of traceability systems

The implementation of traceability systems can aid in efficient post-harvest management. Through proper labeling and documentation, it becomes easier to track and trace the origin of tomatoes, ensuring quality control and reducing the risk of product loss or contamination. v

In conclusion, reducing post-harvest losses in tomato production requires a multi-faceted approach, starting from simple management practices and gradually adopting more complex systems. By implementing proper harvesting techniques, sorting, packaging, temperature and humidity control, post-harvest treatments, and traceability systems, farmers can minimize post-harvest losses in vegetables, increase profitability, and contribute to more sustainable vegetable industries.