PRESERVATION / PROCESSING TECHNOLOGY OF FISHERIES WITH PHYSICAL AND CHEMICAL METHODS

PRESERVATION / PROCESSING TECHNOLOGY OF FISHERIES WITH PHYSICAL AND CHEMICAL METHODS

Preservation / Processing of Fisheries Products by Sterilization / Canning canning 1. FISHING PRINCIPLES The use of heat in preserving foodstuffs is widely known. Various methods are used such as cooking, frying, boiling and other heating is one way of preservation. Through this treatment there is a change in the state of food ingredients, both physical and chemical properties so that the state of the material becomes soft and delicious to eat. Cooking causes most of the microorganisms and enzymes to be damaged so that food that has been cooked is more resistant for several days. Food canning is a way of preserving food that is packaged hermetically and then sterilized. The preservation method was discovered by Nicolas Appert, a French scientist. In food canning, hermetic food is packaged in a container, be it can, glass, or aluminum. Hermetic packaging can mean that the closure is very tight, so it cannot be penetrated by air, water, oxidation damage or taste changes. The durability of canned food varies greatly depending on the type of food, the type of container, the processing / canning process and the conditions in which it is stored. If the processing is perfect, then the durability of the canned product will be longer. Canned food damage generally occurs due to changes in texture and taste compared to microorganisms. Three types of materials are usually used in making cans, which are: Electrolite Tin Plate (ETP), Tin Free Steel (TFS), and aluminum (alum). Most canning using TFS-CT is an electrically coated layer of chromium. As soon as it is coated with chromium, a layer of chromium oxide is formed on the entire surface. This type of TFS has several advantages including being cheaper because it does not use lead and better adhesion to organic material, while the disadvantage is a higher chance of rusting. 2. Microorganisms in Canned Food In food preservation, technically there are several methods that use microbiological principles, namely reducing the minimum number of spoilage microorganisms, reducing microorganism contamination, creating an environment that is not preferred by spoilage microorganisms, microorganisms and killing microorganisms by microorganisms by heating or radiation. Elimination of microorganisms by heating in the process of canning fish in principle causes the denaturation of proteins, as well as deactivating enzymes that help metabolism. The application of heat can vary depending on the type of microorganism, the microorganism phase and the environmental conditions of bacterial spores. The lower the temperature given, the more time is given during heating. The heat provided can destroy some vegetative cells, most or all cells. Most or all of the sterilization can be seen in Table 1 and Table 2. The more the number of spores, the longer the sterilization time. In canning, the thing to watch out for is anaerobic bacteria such as Clostridium botolinum which are resistant to high temperatures. Generally bacteria produce temperatures above 550C. Table 1. Effects of Warming Temperature on Time Needs to Turn Off Bacteria Temperature (0C) Time (Minutes) 100 1,200 105 600 110 190 115 70 120 19 125 7 130 3 135 1 Table 2. Effect of Number of Initial Spores on Time Needed Number of Initial Time Spores (Minutes) 50,000 14 5,000 10 500 9 50 8 3. Sterilization Sterilization is the basic method of preserving fish with canning techniques. Tightly closed cans are heated to deactivate enzymes, kill microorganisms, and convert fish from raw form into products that are ready to be served but have high nutritional content.

Understanding sterilization is an attempt to free tools or materials from all forms of life, especially microorganisms. So, if we say a device or material is sterile, it means that there is no life and activities of microorganisms under normal conditions. All types of microorganisms both pathogenic microorganisms (disease carriers), nonpatogens, spoilers, and others have been destroyed. Warming up the food is done in such a way that microorganisms that are harmful to humans have died, but the nature of the material has not changed much. For this reason, several types of sterilization terms arise, including: a. Biological sterilization Heating that results in the destruction of all forms of life that exist on heated foodstuffs. b. Commercial sterilization is a level such that under normal circumstances it will not be damaged. The material is not 100% sterile but pathogenic bacteria and toxin forming have been turned off. Sterilization is usually carried out at high temperatures above 1000C, for example 1210C for 15 minutes. Sterilization by heating is divided into: a. Incandescent sterilization is usually done for tools such as needle ose, and using a Bunsen burner. b. Sterilization with hot air, the instrument used is an oven with a temperature of 170 – 1800C for 2 hours, and sterilized equipment is usually glass tools that are resistant to high temperatures. It should be noted, after sterilizing the oven do not open to avoid cracks in the equipment. c. Sterilization with hot water steam usually uses steamer equipment as well as steaming, ie using hot water steam. d. Sterilization with hot steam pressurized, the tool used is aotuclave, usually used to sterilize the media. The sterilization time is calculated at the required temperature and pressure of 1.2310C with a pressure of 2 atm ranging between 15-30 minutes. If the sterilization is complete, the aotuclave is left for a while until the pressure returns to normal. Commercial sterilizers are sterilizers that are usually carried out on most food in cans or bottles. Commercially sterile food means that all disease microbes and spore-forming (toxins) in the food have been killed, as well as all spoilage bikrobes. Other microbes may be present in these foods but are beyond our attention. The heat resistance of a microorganism is shown by its Thermal Death Time (TDT), which is the number of minutes needed for a certain temperature. TDT will decrease logarithmic with increasing temperature. That relationship is called Lethality or Letality. Industrial sterilizers for canned food products require retorts equipped with boilers, for small scale autoclave use. A retort is a container where the canned product is sterilized using steam pressure. Forms of retort are vertical and horizontal, the way it works is that there is a stationary position and there is a movement. In the fishing industry that is widely used is silent, batch, both horizontal and vertical. 4. Determine Heating Temperature The level of heat penetration into food must be known to take into account the heat needed in preservation. All parts in the can and their products must receive sufficient heat. Heat can be penetrated by conduction, convection, or a combination of both. Heat propagation can run by conduction, convection, or radiation. In canning food, usually the heat propagation runs by convection or conduction. The nature of heat propagation needs to be considered to determine the optimum amount of heat that must be given to canned food. Convection is the propagation of heat, heat flowed by way of movement or circulation, for example in foods that are liquid like fruit juice. Conduction is the propagation of heat, heat flowed from one particle to another without any movement or circulation of the particle, for example in solid foods such as cornet beef. Canned food or heated material has a place (point) that is the slowest to receive heat, which is called cold point. Conduction of heat by conduction, the cold point is in the middle or in the center of the material. Whereas the cold point convection materials are located below or above the center, which is about ¼ the top or bottom. Heat propagation by convection is much faster than heat propagation by conduction. The more dense the food, the slower the heat propagation. How to calculate the amount of heat that must be given in the canning process is not an easy and simple technique. The heat sterilization process is carefully calculated and must first be understood the type and condition of the material to be processed, the size of the can, and the stages of canning that must be done. Knowledge about the source of contamination, the type of contamination, the environment, and the level of contaminant resistance to heat is also needed to understand the principles of the heat sterilization process. All of this information is needed to calculate the sterilization time and temperature required for a particular product on the size of a can to be able to destroy all spoilage microbes contained in the product. 5. Fish Canning Stages Based on the processing method, canning of fishery products can be divided into several types, namely boiling in salt water, in oil, in tomato sausage, and seasoned. There is also the division of fish canning products on the basis of the form of canned ingredients, in a raw state, or cooked first. Container Preparation Containers to be used should be thoroughly cleaned and inspected before being used for canning. This method, if implemented properly, will result in decay. a. Cans Can (Tin Can) In canning a product, it should be noted to always use the appropriate type of can of the product, with the aim to avoid discoloration. Cans that will be used should be checked for solder, for rust or for other defects, such as curves or dents. Cans that have been deformed should not be used. Good cans are then washed in warm soapy water and then rinsed with clean water. Do not wash the lid to avoid damaging the gasket. Therefore, the lid can always be kept clean, for example wrapped in plastic bags or packed in cartons, so as to avoid dust and moisture. b. Jars Glasses In addition to cans, containers used can use jars, jars are amorphous solids from a solution of silica oxide, calcium, sodium, and other elements. Glass raw materials mainly are sand, soda ash, and carefully selected limestone. Glass containers for food can be divided into two forms, namely wide-mouthed glass (wide mouth) and narrow-mouthed glass (narrow neck) Jars should be examined first, especially in the closure, because canned products will rot if the closure is not perfect. The glass jars are also examined for the presence / absence of cracks, scratches or imperfect finish, while the lid is checked whether it can close properly or not. After the examination, the jar and lid are washed in warm soapy water, then rinsed with clean water, after which the glass is soaked in boiling water for at least 15 minutes. If not, will cause damage to the rubber or gasket lid, glass jars can also be immersed in hot water. If the product filling will be done in a hot condition, then the glass must also be kept in a hot state. The advantages and disadvantages of using cans and glass containers. The benefits of using canned containers: a. Cans can be closed before sterilizing. This is because the ends of the can during heating continue to expand without damaging the joints on the edges of the can. b. Light, easy and fast manufacturing. c. Heat propagation is faster and can be cooled quickly without damaging the can d. Oxygen in the head space reacts quickly with metal components of cans, such as iron and tin so that color bleaching and flavor irregularities can be inhibited. The advantage of using a glass container: a. Transparent / transparent. b. Reduces discoloration (discoloration). c. Reducing rust formation. Weaknesses of the use of glass containers: a. Easily broken. b. Heavier than a can. c. Heat propagation is slower and cannot be cooled quickly. d. Canned products in glass jars must be stored in a dark place to avoid the effects of light. c. Retort pouch Retort pouch is a multi-layered plastic consisting of polyester, aluminum foil and polypropylene, which is designed as a packaging that can compete with the shelf life of tin cans and match the quality of frozen food packaging. Retort pouch has an advantage over can packaging because heat penetration takes place faster and more efficiently so that it can maintain the nutritional state, color, and taste. Overall the product uses a retort pouch whose quality is better, tastier, the color and texture are better when compared to can packaging, more practical in serving, storage also costs much cheaper production. Filling Filling the container with the material that has been prepared should be done immediately after the preparation process is complete. The filling should be done regularly and uniformly. The product is loaded to the desired surface in the container by observing the presence of head space, then the canning medium is loaded later. Head space is the empty space between the product surface and the lid. It functions as a spare room for product development during sterilization, so as not to press the container because it will cause the glass to break or the can to become bloated. a. Filling Methods Filling containers with prepared foodstuffs can be done manually, using semi-automatic machines, and even with automatic machines. The choice of filling method depends very much on the canned product, for example on a product that tastes better. If the jars are used, the filling method is done by the same method, although more special treatment is needed, for example the jars will be placed in the desired place, preferably by placing the glass container in a hot water bath. For jars that use rubber rings, the ring must be placed in place, then the product in a hot state is loaded into the jars, then canning media is added and air bubbles are removed using a small knife. b. Weight Checking The containers are filled with the product until they reach the specified weight. For this purpose, a scale is used, depending on the scale, depending on the can. Weight accuracy is an economic factor reducing the amount of product carried along. For some types of products, the right weight is very important because the sterilization process is further influenced by the amount (volume of weight) of the product. In addition, the right product weight in each operation will instill consumer confidence in the product produced. To meet this weight, sometimes small pieces (debris or broken pieces) are needed. Thus, the contents of cans are divided into 3 (three) types, namely: a. Fancy, consisting of basic pieces. b. Standard, consisting of staples plus splinters. c. Flakes or salads, consisting of pieces of meat. c. Canning Medium Canning medium is a solution or other material that is added to the product during the filling process. The types of medium commonly used are salt solutions, syrups, broths, multi-layer plastic consisting of polyester, aluminum foil and polypropylene, which are designed as packaging that can compete with the shelf life of tin cans and match the quality of frozen food packages. Retort pouch has an advantage over can packaging because heat penetration takes place faster and more efficiently so that it can maintain the nutritional state, color, and taste. Overall the product uses a retort pouch whose quality is better, tastier, the color and texture is better when compared to the tin packaging, more practical and oil. Salt solution is used for food that is not acidic, syrup is used for fruits, broth for meat, and oil is used for fish and other fishery products. The canning medium can give flavor to canned products, and also serves to reduce the time of sterilization, by increasing the heat propagation process, and can reduce corrosion by caning air. Factors that influence the speed of heat propagation in canned foods include: 1) the type of container raw material 2) the size and shape of the container 3) the degree of filling of the container product 4) the viscosity of the liquid 5) the distribution of the product in the container 6) the initial temperature of the product 7 ) location of the container in the heating medium 8) retort temperature, and 9) presence / absence of agitation of the container during sterilization. To a certain extent we can classify the propagation of heat that will occur in the material inside the can, noting its physical properties. Heat propagation in cans can occur by convection (for example in fruit juice), a mixture of convection and production (for example in corn in cream), or conduction (for example in crushed spinach or meat and fish). As is known, heat propagation by convection takes place faster than by conduction. Preparation of salt solutions must be used with high quality salt (NaCl). Salt produced specifically for food canning is preferred, because it is more soluble in water than table salt, and does not easily re-settle. Even so, quality table salt can be used, but iodized table salt (iodized salt) is not recommended. Water to be used to make salt solutions must be free of calcium and magnesium. In some cases it is necessary to heat the water first, then let it settle and filter. Salt solution is made by adding a certain amount of salt to water, usually a 2% salt solution can be used in most canned products. In the manufacture of salt solutions, stainless steel containers or tanks / glass / plastic coated tanks should be used to prevent corrosion of metals. The salt solution used in canning must be heated to boiling and then added to containers (cans / cups) that already contain the product. Some large canning industries, sometimes also use salt in the form of tablets. The salt tablets are placed on the product in a container, then boiling water is added to the container. Syrup is used as a canned fruit medium, except for fruits that are packed solid. Syrup is prepared by boiling sugar (sugar / sucrose) in water for 5 minutes to dissolve all sugar and reduce oxygen levels in syrup. The foam that forms on the surface of the sugar solution during heating should be discarded. The syrup is added to the container containing the product until it is almost full, and after exhausting it is usually added more hot water to fill the container. Broth and oil are used as a canning medium for meat, poultry and fish. The broth is made from skin, bone, fat, or other parts that are not used, by boiling it in water and adding spices. As is the case for making syrup, the froth that is formed is removed. Warming the broth is usually done in a steam jacketed kettle. d. Head Space Head Space is the space between the lid of the container and the surface of the product. The amount varies depending on the general size of the liquid product in the can is about 0.25 inches high, whereas if the container used is glass jars recommended a larger head space. The size of the head soace in the container is very important to note, if it is too small it will cause rupture of the container due to expansion (development) of the product during the sterilization process. If the head space is too large, a small amount of air will be trapped in the can so that it will cause oxidation and discoloration of the product. Exhausting Most oxygen and other gases must be removed from the material in the container before the closing operation. In closed containers, oxygen is not desired, because the gas can act with food or the inside of a can so that it will affect the quality, value of gisi, and the shelf life of canned products. Exhausting is also useful to make room for product development during the sterilization process so that damage to the container due to product pressure from inside can be avoided, it is also useful to raise the temperature of the product in the container until it reaches the initial temperature. In small-scale factories, exhausting is done by pre-heating the product, then the product is loaded into cans in a hot state and the container is closed also in a still hot state. For some types of products, exhaust can be done by adding a medium, such as tomato sauce or a boiling salt solution. Large-scale fish canning factory, exhausting is done mechanically and is called a vacuum package. The principle is to draw oxygen and other gases from the can and then immediately close the container. Empowerment is also useful for: a. Reducing the pressure inside the can, so that the can doesn’t break during sterilization b. Removes oxygen to reduce the possibility of oxidizing the contents of the can and corrosion on the inside of the can because it can cause leakage in the can. c. Maintain vitamin C content. Closure of the container After the can is exhausted it must be closed carefully. A good closure is needed to prevent decay. If a can is used as a container, a good closing will prevent leakage from one can that can cause corrosion in other cans. The closure of tin cans is often referred to as double seaming while the machines used for closing double seamer machines vary in type from those moved by hand to the automatic ones. But in principle the work of the machine is the same, namely carrying out two basic operations. The first operation functions to form or roll up the second operation serves to flatten the rolls produced by the first operation. If the container used is glass jars, then the container is not tightly closed (hermatis) until the sterilization process is complete, that is by simply turning the lid down slowly. After the sterilization process is complete, the closure is strengthened by turning the lid tightly to form a careful closure. Sterilization / Processing Sterilization or better known as processing is the most important operation in canning food. Processing is not only aimed at destroying spoilage and pathogenic microbes, but also is useful for making the product mature enough, which is seen from the appearance, texture, and taste as desired. Therefore, the heating process must be carried out at a temperature high enough to destroy the microbes, but it should not be too high so that the product becomes too ripe. In principle, the heating process applied in the canning or bottling industry, specifically designed is only sufficient to achieve commercial sterilization. This condition is not easy to achieve, but sometimes it can produce undesirable quality changes in the product. In contrast to total sterilization, in commercial sterilization there are still some microorganisms that can still live after heating (sterilization). To avoid the occurrence of undesirable changes, then the method of applying the sterilization process is appropriate and safe and can minimize damage and decrease product quality due to the effects of heat. The process is known as the thermal process or the process of heating food, whose basic principles are taken from the science of thermobacteriology by utilizing the principle of pereira and heat penetration as well as the thermal resistance properties of microorganisms in particular that are able to form spores. Low-acidic foods with a pH above 4.5 require a stronger heating process compared to foods that are acidic and high-acidic, fish that have a near neutral pH, ie 6.8 are usually processed at 1210C with time depending on the speed of propagation heat to reach the coldest point of food in cans, as well as the resistance of microbes that contaminate food. The heat process must be sufficient to deactivate microbes contained in canned food or to achieve commercial sterilization. Inadequate heating can cause economic risks and health risks, because a number of heat-resistant microbes will cause damage to the product, resulting in losses. In addition, if the bacterium Clostridium botulinum does not die, it will produce toxins that can cause death. The process of heating canned food that is considered safe is one that can guarantee that the food is free of Clostridium botulinum. Refrigeration Containers must be quickly cooled immediately after the sterilization process is completed, with the aim of obtaining uniformity (time and temperature) in the process and to maintain the quality of the final product. If cooling is too late, the product will tend to overcook so that it will damage the texture and taste. In addition, as long as the product is at a temperature between room temperature and process temperature, the growth of heat-resistant bacterial spores will be stimulated. In addition, with cooling that results in bacteria that still survive will cause shock so that it will die. Labeling and Storage After cold cans or glass jars are labeled in accordance with the wishes of the manufacturer, labeling is intended to find out the material used and to know when the production time so as to determine the expiration period, and of course by labeling the product will be known to the public. Then pack in a certain number of cartons or wooden boxes. In a canned food factory, temporary storage is often needed, for example due to the large amount of production, in addition to storage also to test the quality of the product before it is marketed, a good storage space is needed. Storage temperature is very influential on the quality of canned food. Too high temperatures can cause damage to taste, color, texture, and vitamins contained by the ingredients, consequently it will cause chemical reactions.

In addition, it will also spur the growth of bacteria that during the sterilization process spores are still alive. To prevent rust from forming on the outside of the can or the growth of mold, the humidity of the storage room should be set as low as possible. Materials that use jars should be avoided from light, because they can reduce the quality of some canned food products due to discoloration and damage to some vitamins. Canned Food Quality Testing and Damage Supervision of canned food production must be carried out during raw material preparation and heating, for this reason it is necessary to do physical and chemical testing as well as microbiological testing. If the canning procedure is carried out correctly and sanitation is observed, damage to canned food is rare. But if it does, then the identification of the types of microbes that cause it will greatly help the effort that must be done to prevent it from re-adventuring again. Physical and Chemical Testing Physical and chemical testing must be able to provide an explanation of the sound of the container when it is struck mechanically, the appearance of the container, the presence or absence of dangerous metal salts in the product. A careful examination must be made of the state of the material and the lid of the can. Any curvature of the can body or cracks in the glass jars must be noted for further examination. Tests must be carried out to see whether or not there are leaks. The quality of closure should be carried out during the canning process to avoid the amount of product wasted. Likewise, the quality of closure, both cans and glass jars must be tested after the container is opened. Canned food products must be checked for color, appearance and smell. Odor aberration is a sign of rot, a change may be due to a reaction between the product and the can. In large canneries carried out on organoleptic testing by trained panelists. To test the quality and taste of the product, the test panel is also useful for testing the acceptance of new products by consumers. Microbiological Testing Microbiological testing is carried out to check the effectiveness of sterilization, product quality, type, and the number of microbes still living in the container and the cause of rot. Generally, microbiological examinations require techniques and equipment that are more specialized than physical examinations and must be carried out by competent laboratories. Sebalum canned food products must be stored beforehand for 10 days for inspection. During this time an observation was made for the presence or absence of decay, for example the tin can develop or leak due to poor closing. If by microbiological examination found canned food products that have decayed it is considered to contain Clostridium botulinum poison. Canned foods that have a pH greater than 4.0; container leakage is usually indicated by a mixture of microbial flora. The presence of microcollus or yeast generally proves the existence of leakage of the container. Canned Food Damage The cause of the damage can be divided in two, namely damage caused by processing errors and leakage cans. The damage caused canned food products that are not commercially sterile. So, the damage arises due to microbial growth. In addition to damage caused by microbes there are still a number of other causes that are non-microbial, including such as containers that are less sterile or due to less high temperatures. These factors include imperfect exhaustion of air in the retort, too much liquid residue in the retort, errors in drying dry products, the nature of the product being slow to hot, physical changes in the product, insufficient filling so that the head space is too large, and heating process errors. Processing Error Underprocessing causes mesophyll microbes to survive. These microbes come from spores that are resistant to high temperatures. Inadequate cooling is when cooling after sterilization is done less quickly to reach an internal temperature of 37-450C, allowing various thermophilic bacteria to still be able to live at their optimal temperatures which are passed slowly when the can is cooled. The time between closing cans and sterilizing cans for too long can cause damage. This type of damage is called inspient spoilage, which is a commercially sterile end product but the contents of the can show symptoms of microbial damage.

Canned fish can also experience a decrease in vacuum pressure, it can be caused partly because of changes in the texture of fish meat. Avoiding the possibility of being unwanted in trade, canned products require a considerable amount of transportation or storage time. Vacuum pressure is set above 10 inches. Canned fish often sticks to the inner product of the lid and the formation of gray lumps on the product surface. This can be prevented by wetting the lid with distilled water. While gray lumps can be avoided by soaking the fish before being put in a can with salt solution for 25 minutes. Canned marine fish sometimes form crystals such as glass from magnesium ammonium phosphate. To avoid this, product cooling must be done quickly because quite a long time in the temperature of 40-500C after sterilization will cause magnifying the formation of crystals. Canned Leaks Canned that is not closed carefully, when the can is cooled in cooling water that does not meet the requirements, will be contaminated by microbes. Very small holes allow microbes to contaminate them. The damage can be seen by the presence of mixed flora, consisting of rod-shaped bacteria and coccus in damaged food. Can leakage can be ascertained through visual inspection and measurement of cans, namely the measurement of the components of the seam (seam). Nonbacteriological Damage In addition to damage caused by microbial activity, there is still damage that is not caused by the activity of microorganisms including: Hydrogen Swell, the damage occurs due to chemical reactions between food and cans that form hydrogen gas. The chemical reaction can take place if the tin layer is not perfect, for example, there are scratches. If corrosion lasts long enough, pinholes will arise on the can and cause the can to leak. Maillard’s reaction occurs in many foods that contain sugar, amino acids, and acids. The reaction produces carbon dioxide (CO2) which in large quantities can cause the can to become bloated, especially if the can is stored at high temperatures. Damage due to storage at the level 40-450C, the cause of damage in the form of thermophilic bacteria forming spores that are very heat-resistant.

The bacteria grow at 550C. Some of these, facultative thermophilic which is nonpatogenic, but can cause food damage (spoilage bacteria). In addition to damage caused by microbial activity, there are still damage that is not caused by microorganism activity including: Flat, both ends of the can surface are flat and sturdy. Flipper, the can looks flat, but when pressed with a finger at one end of the surface, the other end will surge out (convex). If the convex tip is pressed, the tin will return flat. A tin springer with one part of both ends is permanently convex. If the convex part is pressed hard enough it will concave again, but the other end part will surge out (convex). Soft well cans which are convex at both ends, but not too hard, so with the help of the thumb, they cannot be pressed a little inward. Hard well, the can at the two ends is convex and very hard, so it cannot be pressed inward with the thumb. Hydrogen swell, the distillation of the can is special, inside the can is produced hydrogen gas, due to corrosion of the container by the product. Hydrogen bloating occurs more slowly than bloating due to bacterial gas formation. Usually canned food products look normal or look paler but there is no indication of rot. Although canned products are usually sterile, hydrogen bubbling cannot be immediately distinguished from bubbling caused by a microbiological process, and is therefore declared unable to be consumed anymore. Stack burn, occurs due to imperfect cooling, that is, cans that have not been completely cold have been stored. Usually the product in the can becomes soft, dark in color, so it cannot be consumed anymore. 8. Summary Sterilization of life forms is an effort to free tools or materials from all forms of life, especially microorganisms. Biological sterilization is a level of heating that results in the destruction of all forms of life that exist in heated food. Commercial sterilization is a level of sterility such that under normal circumstances it will not be damaged. The material is not sterile 100% but the pathogenic bacteria and toxin forming have been turned off. Sterilization is usually carried out at high temperatures above 1000C for example 1210C for 15 minutes. Canning is a way of preserving fishery products that are hermetically packaged and then sterilized. The containers used can be in the form of cans, glass or aluminum. . 9. Questions Explain the meaning of commercial sterilization! Explain the basic principle of canning! Distinguish between conduction and convection! Mention the stages of fish canning! Mention the advantages and disadvantages of glass containers and tin containers! Mention and explain 5 examples of canned food damage! 10. GLOSSARY Aw: The amount of free water needed for the growth of microorganisms. Anaerobic bacteria: Bacteria without oxygen that can still live. Pathogenic bacteria: Bacteria that cause disease. Cornet beef: Smooth canned beef canned. Cold point: The point that is the slowest to receive heat. Toxin: Toxins produced by microorganisms.