Definition of the overview of the most cupped food

The definition and characteristics of canned food:

canned food - raw materials are pretreated → canned (put into a container that can be sealed) → exhaust, seal, sterilize, cool, and the products are made through this series of processes

features:

① there must be a container that can be closed (including a soft bag made of composite film)

② it must be smart and flexible, and it must go through four processes: exhaust, sealing, sterilization and cooling

③ theoretically, pathogenic bacteria, spoilage bacteria and toxic bacteria must be killed. In production, it is called commercial sterility, and the enzyme must be inactivated

the official emergence of canned food is now recognized to be due to Apel of France, who invented the method of food preservation in 1810 - all kinds of food cooked in boiling water and tightly sealed bottles can be stored for a long time, which was once known as Apel technology

in fact, the working people in China have long developed and applied the possibility of using sealing and heat treatment to preserve food. The Beishan Wine Classic (1117) written by Zhu Yizhong in the Song Dynasty also mentioned the method of adding medicine to bottled wine, sealing, boiling, and then standing on Lime for storage. But Abel systematically researched and developed canned food and wrote a book for publication

the method of storing food in cans has a history of less than 200 years, but can storage has become the most important processing technology in the food industry. After venting, sealing, sterilization and cooling, food is stored in closed containers that are no longer polluted by external microorganisms, which can be stored for a long time and no longer cause deterioration

however, during the half century since the invention of canning technology, no microorganisms have been found, and there is a lack of correct understanding of the basic principle of preservation. Therefore, the progress is relatively slow

the development of canning sterilization technology is a milestone in the history of canning industry. In terms of sterilization methods, it is also developing continuously. From the beginning, it takes 6 hours to sterilize with boiling water bath, and later with salt water bath (CaCl2), the temperature is higher, up to 115.6 ℃), and the time required for sterilization is shortened. The quality of canned food has been significantly improved, and then came high-pressure sterilization. Now there are high-temperature short-term sterilization, ultra-high temperature short-term sterilization and so on

the emergence of cans from glass bottles and cans at the beginning, hand-made metal cylinders, to later three piece cans and two piece cans, cans made of aluminum alloy, and later cooking bags made the varieties of cans more novel, diverse and practical

canning technology has also evolved from completely manual operation at the beginning to modern food industry with mechanized safety production today

canned food not only meets the daily needs of the people, but also is more important under special conditions, such as navigation, exploration, military supplies and so on

China's canning industry was founded in 1906 and has only a history of more than 90 years. Shanghai Taifeng food company is the first cannery in China, and then the coastal provinces have built cannery successively. By 1949, the total output of canned food in China was 484 tons. By 1995, the total output of canned food in China had reached more than 310 tons, and there were more than 2000 canning enterprises

all kinds of cans in China have been exported to more than 100 countries and regions, and many products have been highly praised by foreign countries and contribute to the safe operation of batteries in the whole service life cycle, and enjoy a certain reputation

China's Canned export volume ranks eighth in the world, mainly including canned mushrooms, ranking first in the world, accounting for 40% of the world. Others include canned stone knives and cypresses, canned green beans, ketchup, in addition to litchi, longan, loquat, etc

although China's canning industry has developed greatly, there is still a considerable gap between China and foreign advanced countries in terms of the output of canned products, varieties and specifications, packaging and decoration, product quality, trade volume, labor production efficiency and so on

at present, the total output of canned food in the world has reached more than 5000 tons. There are many kinds of canned food with wide uses, including small household food cans, public food cans, travel cans with convenient opening, various curative effect cans, high altitude, high mountain, cosmic cans for special needs, and nutritional cans for infants and children. From empty cans to solid cans, from raw materials to food, almost all have special equipment$ Considering the long-term development of China's canned food industry, we should strengthen the following work:

breeding and propagation of raw material varieties suitable for processing, improvement of processing technology and equipment, and development and use of new packaging containers. The detection of microorganisms, pollutants, additives, nutrients in food, harmful and toxic components, pesticide residues and the prevention and control of three wastes

I. The relationship between canned food and microorganisms

microorganisms mainly include bacteria, molds and yeasts. The spoilage effect of molds and yeasts is important before canning food raw materials. Except for spoilage in a few special products or cans with sealing defects, they generally cannot withstand the heat treatment of canning and operate under sealing conditions

the rubber and Plastic Machinery Research Institute of Beijing University of chemical technology conducted in-depth research on the 1-type gear pump extruder

bacteria are the most important microorganisms that cause the spoilage of canned food. The sterilization theory and calculation standard we now use are based on the lethal effect of a certain kind of bacteria

bacteriological sterilization refers to absolute sterility, while canned food sterilization refers to commercial sterility. Its meaning is to kill pathogenic bacteria and spoilage bacteria, not to kill all microorganisms. Strict control of sterilization temperature and time has become a very important thing to ensure the quality of canned food

(I) general habits of spoilage microorganisms

1 Requirements for living substances

food raw materials contain nutrients required for microbial growth activities, such as sugar, starch, oil, vitamins, protein and various necessary salts and trace elements, which are the basic conditions for microbial growth

the existence of a large number of microorganisms is an important reason for the deterioration of cans. Therefore, the cleaning and hygiene management of food processing plants from raw material processing to finished products is very important

2. Requirements of microorganisms for water

the absorption of nutrients by microorganisms is carried out by osmosis and diffusion in the state of solution. Therefore, only in the presence of sufficient water can normal metabolism be carried out. Reducing water limits the growth activities of microorganisms. For example, some low acid food cans can be safely preserved when the water content is less than 25-30%

3. Requirements for oxygen

microorganisms have very different needs for oxygen. According to the requirements for oxygen, they can be divided into:

aerobic microorganisms

anaerobic microorganisms

facultative anaerobic microorganisms

in terms of canning, aerobic microorganisms are limited, and anaerobic microorganisms are an important factor. If they are not killed during heat treatment, it will cause the deterioration of canned food

4. Acid adaptability

refers to the free acid in the product, not the total acid

different microorganisms have the most suitable pH range for growth. The important role of the pH of the product on bacteria is to affect its resistance to heat. At a certain temperature, the lower the pH value, the more about 25000 employees of DSM and its associated companies have created an annual sales of about 10billion euros. The more significant the reduction of the anti heat of bacteria and spores is, which also improves the sterilization effect

according to the strength of food acidity, it can be divided into:

acidic food (pH4.5 or below)

low acid food (pH4.5 or above)

some foods are also divided into:

low acid food (pH 4.5)

acidic food (ph4.5-3.7)

acidic food (pH 3.7)

in practical application, pH4.5 is generally used as the dividing line

thermophilic spore producing anaerobic bacteria are the most important microorganisms in low acid foods, such as Spoilage Bacterium pa3679, which is usually used as the standard for sterilization

a kind of acid tolerant microorganisms that cause spoilage in acidic foods have no special heat resistance

5. Biological heat tolerance

cereal microorganisms have their optimal growth temperature. If the temperature exceeds or falls below this optimal range, their growth activities will be affected, inhibited or killed

according to the range of adaptation to temperature, it is divided into the following categories:

(1) the optimal temperature for the growth of psychrophilic microorganisms is 14-20 ℃

mold and some bacteria can grow at this temperature, and they have little impact on food safety

(2) the activity temperature range of thermophilic microorganisms is 21-43 ℃

these microorganisms are easy to cause the deterioration of canned food, and many toxin producing spoilage bacteria adapt to this temperature

(3) the optimal temperature of thermophilic microorganisms is 50-65.6 ℃, and the lowest temperature is about 37.8 ℃, and some can grow slowly at 76.7 ℃

the spores of these bacteria are the most heat resistant, and some can survive at 121 ℃ for more than 60 minutes. These bacteria do not produce toxins in food spoilage

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II. Factors affecting sterilization:

(I) types of microorganisms

the heat resistance and acid resistance of microorganisms have different effects on the efficacy of sterilization, but the sterilization effect involves bacteria, and the following factors should also be considered:

1. Types of contaminated microorganisms in food

there are many types of contaminated microorganisms in food. Different types of microorganisms have significantly different heat resistance, Even if the same bacterium has different strains, its heat resistance is also quite different. Generally speaking, non spore bacteria, molds, yeasts and spore bacteria have low heat resistance of vegetative cells

vegetative cells can be killed in a short time when heated at 70-80 ℃. Bacterial spores