Lesson Notes By Weeks and Term v4 - SHS 3

Lesson Video

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Performance objectives

• Describe the steps in processing fish into various products.
• Explain the importance of proper storage for fish products.
• Identify different marketing strategies for selling fish.
• Understand how to process fish into secondary products.

Lesson summary

Fish is a cornerstone of the Ghanaian diet and economy. From the grilled tilapia served with banku to the smoked herrings (amane/kpanla) that flavour our soups and stews, fish is everywhere. However, fresh fish is highly perishable and can spoil within hours of being caught. This is where post-harvest technology becomes crucial. By understanding how to properly process, store, and market fish, we can reduce waste, add value, create jobs, and ensure a stable supply of this vital protein source for families across Ghana. This lesson will equip you with the practical knowledge of the journey of fish from the canoe or fish pond to the consumer's plate.

Lesson notes

A. Core Definitions Fish Processing: This refers to any action or method that alters fresh fish from its original state to make it more suitable for consumption, cooking, or storage. The main goals are to slow down spoilage (preservation) and to add value (e.g., improve taste, texture, or convenience). Fish Storage: This involves keeping fish and fish products in a controlled environment to maintain their quality and prevent spoilage until they are ready to be sold or consumed. Fish Marketing: This includes all the activities involved in moving fish and fish products from the point of production (e.g., the fisherman at the shore) to the final consumer. It involves transportation, packaging, pricing, and selling. B. Procedures for Processing Selected Fish

Fish spoilage is primarily caused by the action of enzymes, bacteria, and chemical oxidation. Processing methods aim to stop or slow down these actions. Smoking This is the most common method of fish preservation in Ghana. It involves exposing fish to smoke from burning wood, which cooks the fish, dries it, and imparts preservative chemicals from the smoke. Principle: Heat from the fire cooks and dries the fish, while chemicals in the smoke (like phenols) kill bacteria and prevent fat from going bad (rancidity). Procedure (using Tilapia or Mackerel): Preparation: De-scale, gut (remove intestines), and wash the fish thoroughly with clean water. Large fish may be cut into smaller pieces. Salting/Spicing: Lightly rub the fish with salt (and sometimes spices like ginger or pepper). This helps to draw out some moisture and adds flavour. Arrangement: Arrange the fish neatly on wire mesh trays (racks). Ensure they do not overlap to allow for even smoke circulation. Smoking: Place the trays in a smoking kiln or oven. The most improved traditional kiln is the Chorkor Smoker. A fire is started at the bottom using hardwood (which produces less tar and more smoke). Control: The fish is hot-smoked at a temperature of 60-80°C. The process can take several hours to a few days, depending on the fish size and desired moisture content. The trays are periodically rearranged to ensure even smoking. Finished Product: The final product is golden-brown, firm, and has a characteristic smoky aroma and flavour. Salting This method uses salt to draw water out of the fish flesh through osmosis, making the environment too dry for spoilage microorganisms to survive. Principle: Osmosis. High salt concentration outside the fish draws water out of the fish cells, dehydrating them and the bacteria within. Procedure (used for creating "Koobi" - salted tilapia, or "Momoni" - salted fish): Preparation: The fish is gutted and washed. It may be split open to increase the surface area for salt penetration. Salting Methods: Dry Salting: The fish is buried in coarse salt or rubbed thoroughly with a generous amount of salt. The fish are then layered with salt in a container (e.g., a barrel or basket). Brining (Wet Salting): The fish is immersed in a concentrated salt solution (brine) for several days. Curing: The fish is left to cure for several days or weeks. During this time, the salt penetrates the flesh, and water is drawn out, forming a brine at the bottom of the container. Drying: After curing, the salted fish is often sun-dried for a few days to further reduce moisture content and harden the product. Ghanaian Example: Koobi is a classic example of dry-salted and sun-dried tilapia. Sun-Drying This is a traditional and low-cost method that uses heat from the sun and air movement to remove moisture from the fish. Principle: Evaporation. Solar energy heats the fish, causing the water within it to turn into vapour and evaporate into the air. Procedure (used for Herrings "amane" or Anchovies "keta school boys"): Preparation: Small fish are often dried whole after washing. Larger fish are split open and gutted. Arrangement: The fish are spread out in a single layer on raised racks, mats, or clean concrete slabs exposed to direct sunlight and wind. Raised racks are best as they allow air to circulate all around the fish and protect them from dirt and animals. Drying: The fish are left in the sun for several days. They must be turned regularly to ensure even drying. Protection: At night or during rain, the fish must be covered or moved indoors to prevent them from reabsorbing moisture. They also need protection from flies and pests. Finished Product: A very dry, lightweight, and hard product with a long shelf life. Example: Kako. Frying This method uses hot oil to cook and dehydrate the fish, giving it a crispy texture and desirable flavour. Principle: The high temperature of the oil (150-190°C) rapidly cooks the fish and drives out moisture from the surface layers. Procedure (used for any fish, commonly "Chofi" - fried turkey berries with fish): Preparation: Clean, gut, and wash the fish. It can be cut into pieces. Seasoning: Season the fish with salt, pepper, and other desired spices. Some people coat it in flour for extra crispiness. Frying: Heat a sufficient amount of cooking oil (vegetable, palm) in a pan. Carefully place the fish in the hot oil. Cooking: Fry until golden brown and cooked through, turning once. Cooling: Remove the fish from the oil and place it on a rack to drain excess oil and cool. Frying is mainly for immediate consumption but can preserve fish for a few days if kept properly. C. Storage of Fish and Fish Products

Proper storage is essential to maintain the quality achieved through processing.

| Type of Product | Storage Method | Key Conditions and Explanation | Duration | | :--- | :--- | :--- | :--- | | Fresh Fish | Icing / Refrigeration | Fish is placed in a cooler or container and covered completely with crushed ice. The low temperature (around 0°C) slows down bacterial and enzymatic action significantly. Refrigerators serve the same purpose for household storage. | Short-term (1-5 days) | | Fresh Fish | Freezing | Fish is kept in a deep freezer at temperatures below -18°C. This stops all microbial and enzymatic activity, preserving the fish for a very long time. This is the basis of the "cold store" business in Ghana. | Long-term (Months) | | Smoked Fish | Dry, Ventilated Storage | Smoked fish should be stored in a cool, dry, and well-ventilated place. They are often kept in baskets ("adetse") that allow air to circulate, preventing mould growth. For longer storage, they can be re-smoked periodically to keep them dry. | Weeks to Months | | Salted/Dried Fish | Dry, Pest-proof Storage| These products have very low moisture and are stable at room temperature. They must be stored in sacks or containers that protect them from insects (like beetles) and rodents. The storage area must be very dry to prevent reabsorption of moisture. | Months to over a year | | Fried Fish | Cool, Dry Place / Refrigeration | Fried fish can be kept at room temperature for a day or two in a covered container. For longer storage (up to a week), it should be refrigerated. | Short-term (Days) | D. Marketing of Fish and Fish Products

Evaluation guide

• Describe the procedure for processing, marketin g and storage of produce
• and products from selected fish.
• Think -pair-share: Learners in pairs revise the meaning of processing, storage and
• marketing of fish products.