Head of Gastronomy and Culinary Arts Department Prof. Dr. Aziz Ekşi said that certain rules should be followed when processing fruits and vegetables into canned food at home. Ekşi, who said that if the scientific rules are not followed, especially when canning vegetables, it is possible to experience food poisoning and beyond that, events leading to death, emphasized that it is mandatory to follow the rules of canning.
Ekşi said, “When we talk about canned food; We understand the vegetables or fruits put in the jar, the filling water, the jar with the lid closed so that no air can enter, and the keeping of this jar at a certain temperature for a certain period of time. The purpose of this is to kill bacteria and similar microorganisms that cause food spoilage. When we provide this, we gain a certain shelf life to canned food. This process is done either in boiling water, i.e. 100 degrees Celsius and below. We call this pasteurization. This process is sufficient for fruit preserves. Because they are high in acid. But it is not enough for canned vegetables. Because in order to kill bacteria that cause spoilage in canned vegetables, the temperature must rise above 100 degrees Celsius. This temperature is usually between 115-121 degrees Celsius. This can only be achieved with pressurized devices such as a pressure cooker but with a thermometer on the lid and called an autoclave. Only then can we control the desired temperature and time. We call this application over 100 degrees Celsius as sterilization.”
‘YOU MUST FOLLOW THE RULES’
Ekşi stated that the most important difference between canned vegetables and canned fruits is due to its low acidity. Saying that microorganisms that develop and cause deterioration in foods with such low acidity are generally resistant to heat, Ekşi said:
“This is why we go above 100 degrees Celsius so that we can kill these resistant microorganisms. If we do not kill these microorganisms and they remain alive in the can, they can form harmful compounds in the airless environment of the can. In particular, there is a bacterium called ‘clostridium botulinum’. This bacterium is soil-borne and can infect vegetables. Even if we wash it, it can still stay on the vegetables. If we do not meet the conditions I said, that is, if we do not keep it at the prescribed temperature and time, this bacteria can survive in the can. Be especially careful when canning vegetables. If we do not apply sterilization, we cannot kill the bacteria called ‘clostridium botulinum’. When it fails to kill, it creates a toxin that causes death in the stuffy environment of the can. This toxin is neurotoxic. In other words, it is a poison that disrupts the function of the nervous system. Depending on the amount formed, the person may first start to see double. Respiratory difficulties may occur. There may be difficulty in swallowing and partial paralysis. More importantly, it can lead to respiratory paralysis and death. Therefore, you should not take this risk. You shouldn’t say ‘he won’t find me’. Therefore, we must strictly follow the rules of canning. We have to be especially careful when making canned vegetables.”
‘A CANNED PRODUCTION CENTER SHOULD BE ESTABLISHED’
Ekşi pointed out that this situation can be experienced in all vegetables, and bacteria called Clostridium can develop in beans, peas, eggplant, zucchini, carrots, in other words, all vegetables except tomatoes, which have a slightly high acidity. This also applies to canned meat and fish. If we do not comply with the sterilization conditions, we can make these foods that we make safe at home, on the contrary, harmful. “These autoclaves, which I call pressure cooker-like, also have a valve to evacuate the air or to turn it off and raise the temperature. But it is also necessary to have a temperature indicator on the lid. When we close the valve, we should see ‘how many degrees Celsius’ it has come. Let’s say we want 121 degrees Celsius and we got there. If we turn the fire down, the temperature stays at this level. Let’s say we want to keep it at this temperature for 20 minutes, we need to keep it on low heat for that long and then leave it to cool. In other words, we cannot do this with any device that does not have a temperature indicator. There are also home scale devices of this type. Necessary information can be obtained from the District Directorate of Agriculture in this regard. It can be difficult to get these devices home one by one. My suggestion is to organize on a neighborhood basis, to create a canned food production center in a cooperative-like structure, to buy these devices there, and to produce this type of food in a safer way for families who want it, through imece, respectively.”
‘THE COVER IS VERY IMPORTANT’
prof. Dr. Ekşi noted that the pandemic also created an insecurity against food, but it is known that the virus is not transmitted through food, and said:
“If people are canning at home, especially canned vegetables, they need to boil the vegetable well so that the air in the vegetable tissue can escape. Then put vegetables up to 3/4 of the jar. Add salt water, called fill water, on it. The filling water must be as hot as possible so that the air in the jar is removed and an airless environment is created. Another rule is to leave about 1 centimeter at the top of the jar. Because the temperature will rise during sterilization, vegetables may expand and force the lid. When we add the filling water, we close the lid immediately. The cover is very important, the cover must be sealed. In other words, there should be a rubber-like seal on the side of the jar, so that it can be closed so that no air enters. Usually old covers are used. This is very false. If they use the old cap, the gasket may be deformed, hardened, and it is thought to be closed but may leak air. It is very important that it is not airtight. Then we place the jars in the autoclave for sterilization. Here, too, the temperature and time must be strictly adhered to. This can vary from can to canned, depending on the size of the jar. In general, 20-25 minutes between 115-121 degrees Celsius is sufficient.”
‘CAN BE STORED FOR 2 YEARS’
Expressing that if a food is pasteurized or sterilized, room temperature is sufficient for its storage, Ekşi said, “The lower the temperature, the better. However, there is no significant disadvantage in storing it at room temperature, unless the lid is opened. As long as air does not enter the jar, if air does, microorganism can also be transmitted from the air and start to spoil the can. Therefore, as long as the lid is not opened, the shelf life of these foods is generally 2 years, it may be more, but other quality characteristics may change. Even if it is not spoiled, its color and taste may change. It can be stored for 2 years at normal temperature without spoiling.