Comprehensive knowledge of food packaging, preserv

2022-08-08
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Comprehensive knowledge of canned food packaging, preservation and storage III

IV. canned containers

(I) conditions that canned containers should meet:

1 It is not toxic to human body, does not pollute food, and ensures that food meets health requirements

2. It has good sealing performance, ensuring that the food is isolated from the outside air after disinfection and sterilization, preventing microbial pollution, so that the food can be stored for a long time without deterioration

3. Good corrosion resistance

because all kinds of canned food generally contain organic compounds such as sugars, proteins and inorganic salts, some chemical changes will occur in the production process of canned food, which will decompose into corrosive substances. Canned food will also change slowly during storage, corroding containers, and even causing perforation and leakage

4. It is suitable for industrial production and can withstand all kinds of mechanical processing

it can meet the requirements of factory mechanization and automatic production, with consistent container specifications, high productivity, stable quality and low cost

5. The container should be easy to open, easy to eat, small in size, light in weight, easy to carry and convenient for consumption

(II). Commonly used can containers

at present, the containers used for can production mainly include tinplate cans, chromium plated sheet cans, aluminum alloy sheet cans, glass cans, plastic cans and composite plastic film bags. The following describes several commonly used can containers:

1. Thin tin sheet cans (tinplate cans), referred to as iron cans

tinplate cans are low-carbon steel sheets with tin on both sides, with a carbon content of 0.06-0.12% and a thickness of 0.15-0.49 mm

is a five layer structure, including: steel base, alloy layer, tin layer,

oxidation film layer, oil film layer

(1), steel base

(2), alloy layer

(3), tin layer

(4), oxidation film layer

(5), oil film layer

2, aluminum alloy sheet cans (aluminum cans)

aluminum and aluminum alloy sheet cans are pure aluminum or aluminum manganese and aluminum magnesium are cast and rolled in a certain proportion.Annealed with metallic luster Metal materials with light weight and certain corrosion resistance

this kind of tank is light and convenient for transportation; It is resistant to atmospheric corrosion and does not rust; Generally, it will not be dyed by sulfur-containing products; Easy to become the future Jixi to find new growth point type; Aluminum free, non toxic

but with low strength and easy deformation; Inconvenient for welding; Bleach the product; The service life is less than that of tin cans; The cost is more expensive than tinplate

aluminum cans seem corrosion-resistant, but experiments have proved that they can still react with food. If aluminum cans accelerate the transformation and industrialization of relevant technological achievements, internal coatings must be used for fruit and vegetable processed products, so the cost will be greatly increased

3. Glass cans

glass cans (bottles) account for a large proportion of canned food and are made of glass

glass is quartz sand (silicic acid) and alkali, that is, amorphous solidified inorganic substances formed in slow cooling after melting neutral silicates

there are many kinds of glass, which vary with the ingredients. The glass cans (bottles) for food are made of soda lime glass, that is, quartz sand, soda ash (Na2CO3) and limestone (CAO) are fused at 1500 ℃ in a certain proportion, and then slowly cooled and molded

characteristics of glass cans:

chemical properties are stable, and generally do not react with food; It can directly observe the color and shape of the products in the tank, and produce attraction or disgust; Reusable; Abundant raw materials and low cost; The level of scientific and technological innovation and utilization has been greatly improved, with high hardness and no deformation

but poor thermal stability; Fragile and fragile; Heavy weight; Low thermal conductivity; Because of its light transmission, it has a discoloration reaction to some pigments

glass bottle is composed of three parts: bottle body, bottle cap and bottle ring

4. Soft can

is made of composite film composed of polyester, aluminum foil and polyolefin

this kind of soft can packaging has the following characteristics:

① it can withstand high temperature sterilization, microorganisms will not invade, and the storage period is long

② airtight, water vapor and contents are almost impossible to have chemical action, which can maintain the quality of contents for a long time

① light weight, good sealing, simple and firm sealing, and can be electrically sealed

② fast heat transfer during sterilization

③ easy to open and beautiful package

the use of flexible packaging is considered to be the innovation of canning industry technology, and soft cans are called the second generation of cans

The success of the research on cooking bags is considered to be an important progress in the development of canned food technology in food packaging. With the development of high-temperature instant sterilization and canning technology, soft canned food is better than traditional canned food in terms of color, aroma, taste, food morphology, manufacturing technology and overall strength to further improve the nutritional value. (to be continued)

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