The hottest meat products packaging materials and

"Meat products" packaging materials and packaging technology (Part 2)

3. Meat packaging technology

3.1 packaging of fresh meat

fresh meat quality generally refers to meat color, flavor, juiciness, tenderness, muscle tissue, etc., in which meat color is the simplest and most important index to judge quality. Meat color is mainly based on the natural changes of three myoglobins - myoglobin, oxygenated myoglobin and denatured myoglobin in the atmosphere. In the case of high oxygen partial pressure, oxygen permeates and surrounds myoglobin molecules, and combines with iron ions in proheme to form oxygenated myoglobin, producing bright red flesh color, while oxygen continues to combine and dissociate with proheme. At lower oxygen partial pressure, myoglobin and oxygenated myoglobin turn into brown denatured myoglobin. Therefore, the packaging material with good oxygen permeability should be selected for the packaging of fresh meat, but this packaging material is only used for the short-term storage of fresh meat, because fresh meat will turn brown after being placed in the atmosphere for too long, which will also increase the growth of microorganisms and the oxidative rancidity of fat. The common fresh meat packaging methods in actual production are as follows

3.1.1 tray

generally, the refrigerated meat sold in supermarkets is mostly palletized with PO (therefore lystyrene; polystyrene), and the bottom of the pallet is padded with absorbent paper to absorb the meat juice, which makes the meat particularly bright red and stimulates consumers' desire to buy

commonly used packaging machine 'target=_ Blank> there are several kinds of transparent membrane materials: (1) cellophane, coated with nitrocellulose on one side, can absorb the moisture on the surface of meat and become saturated when contacting with meat on this side, so as to promote oxygen penetration to maintain good color and reduce weight loss. However, it is not applicable if nitrocellulose is coated on both sides of cellophane

(2) polyethylene: referred to as PE, it can be divided into low-density PE, medium density PE and high-density PE. It has high oxygen permeability, especially low-density PE. In addition, it has good acid-base resistance, oil resistance and water vapor permeability, which is very suitable for packaging fresh meat. The only disadvantage of this material is its poor tensile strength and friction resistance

3.1.3 vacuum packaging

vacuum packaging refers to extracting all the air in the packaging and cooperating with the packaging materials with extremely low oxygen permeability, so that the external oxygen can not penetrate into the packaging, reducing the rate of oxidation and rancidity of fresh meat to ensure the freshness of fresh meat. Vacuum packed fresh meat can be stored for 14 ~ 20 days at 0 ± 1 ℃. The shelf life of vacuum packaging itself is 5 ~ 7d longer than that of pallet packaging, but after vacuum packaging, due to the blocking of oxygen, the general meat will be dark red, which will damage the appearance. However, if the cooled meat returns to bright red color in the presence of oxygen after the packaging is removed, vacuum packaging is generally used in hotels and shopping malls that require long storage time and high quality

the materials used in vacuum packaging include polyester and polyamide, in addition to polyvinylidene chloride (PVDC) with good oxygen permeability and shrinkage; Or nylon, polyester film and polyethylene multilayer materials. Polyvinylidene chloride has the highest permeability to prevent oxygen and water vapor, but its biggest disadvantage is that it cannot be heat sealed. Polyester has strong tensile strength and softness; Nylon has good anti oxygen permeability, good heat and cold resistance, and strong mechanical properties, but it has high water vapor permeability and is expensive, so it is often used as a material for vacuum packaging of fresh meat in the form of multi-layer composite

3.1.4 modified atmosphere packaging

modified atmosphere packaging, also known as inflatable packaging, is to pump out the air in the packaging bag and then fill it with a certain proportion of nitrogen, carbon dioxide and oxygen, so as to minimize the possibility of oxygen infiltration, inhibit the growth and reproduction of microorganisms, and then extend the fresh-keeping period of products. The modified atmosphere packaging of cold fresh meat can also maintain the color of meat. This kind of packaging form is currently in the stage of experimental research in China

3.1.5 vacuum heat shrinkable packaging

vacuum heat shrinkable packaging can also be used for the packaging of large pieces of meat. The advantage of this packaging form is that it can not only effectively reduce the bag breaking rate, but also eliminate the juice exudation phenomenon of vacuum packaging. The treatment of vacuum heat shrinking can not only inhibit the reproduction of aerobic bacteria on the surface of chilled meat, but also prevent the secondary pollution of chilled meat, and effectively extend the shelf life. Compared with modified atmosphere packaging, it is convenient for transportation and low packaging cost. Vacuum heat shrinkable packaging is widely used in developed countries in Europe and the United States. It is a packaging method worthy of reference for cooling meat packaging in China

3.2 packaging of frozen meat

in addition to preventing oxygen and water vapor from penetrating to avoid oxidative rancidity of fat, frozen meat packaging materials must also be able to adapt to rapid changes in temperature and shrink or expand with freezing or thawing operations

3.2.1 aluminum foil

can be compounded with other materials to form flexible packaging materials for packaging frozen food. At the same time, it can also be processed into semi-rigid packaging containers of various shapes to package meat or instant food. Its waterproof vapor permeability and gas permeability are excellent, but its shrinkage and heat sealing are poor

3.2.2 plastic film composite materials

such as nylon and polyethylene, polyethylene and polyester film, low-density polyethylene, polypropylene coated with polyvinylidene chloride and other multi-layer composite packaging materials, are commonly used to package hamburgers, steaks, etc., and then put them into waxed cartons for freezing preservation

3.3 packaging of processed meat products

in order to maintain the quality of processed meat products, the selection of packaging materials for meat products should consider the characteristics of their production, processing, storage and eating methods. There are many packaging materials for meat products. The commonly used packaging materials can be divided into natural casing, artificial casing and other packaging materials

3.3.1 natural casings

natural casings are mainly processed from the small intestine, large intestine and bladder of pigs, cattle and sheep, with Pig casings and sheep casings being the most commonly used. Selection can be based on product quality and size characteristics. The processed natural casings are divided into two types: salted and dried. Before using the salted casing, rinse it repeatedly in clear water to fully wash the salt and dirt on the surface of the casing; Dry casings should be soaked in warm water to make them soft before use. The advantage of natural casing is that it has good toughness and firmness, can withstand the tension and heat treatment in processing, and has the properties of shrinkage and expansion. The disadvantages are uneven thickness, high cost and limited sources, which are not suitable for large-scale automated production

3.3.2 artificial casings

artificial casings include collagen casings, cellulose casings and plastic casings. The advantages of artificial casings are unified specifications, convenient processing, suitable for large-scale production, while preserving the flavor of products, extending the shelf life, reducing dry consumption and so on. At present, artificial casings have been widely used in the world. In addition to the import of some artificial casings, China has begun to mass produce artificial collagen casings and plastic casings

(1) collagen casings

made of animal glue, have the characteristics of good permeability, smoking, unified specification, sanitation, firmer than natural casings, and mass production. Collagen casings can be divided into edible and inedible. Edible ones are suitable for making smoked and boiled sausage products, while non edible ones are mainly used for air dried sausage

(2) cellulose casing

cellulose casing is a seamless cylindrical film made of short cotton wool and pulp as raw materials, which has toughness, shrinkage and coloring, unified specification, sanitation, ventilation, smoking and printing on the surface. This kind of sausage with small caliber is mainly used for smoking and baking sausage without casing and small sausage. After smoking and cooking, it is cooled by cold water spraying, and the sausage is removed and sold after secondary packaging; Large diameter cellulose casings can produce and process smoked ham. After smoking, cooking and cooling, it is not necessary to remove the casings. The secondary packaging can be directly carried out to design a user-friendly, complete control function, strong real-time performance, good portability, short development cycle and high reliability utilization system

(3) plastic casing

plastic casing is a single-layer or multi-layer composite cylindrical or sheet casing made of polyethylene, polypropylene, polyvinylidene chloride, polyester plastic, polyamide, etc. It is characterized by tasteless and odorless, high oxygen and water resistance, certain thermal shrinkage, which can meet different hot processing requirements, good mechanical filling performance, safety and health. This kind of casing is widely used in the packaging of high-temperature cooked ham sausage and low-temperature ham products

3.3.3 other packaging materials

(1) aluminum foil. It is suitable for high-temperature sterilization packaging of traditional meat products and has a long shelf life

(2) shrink bag. Using multi-layer composite materials, it has high oxygen and water resistance, heat sealing, shrinkage and printing properties. Using vacuum packaging can improve the shelf life of products. Used for secondary packaging of low temperature meat products

(3) stretch the film. Stretch film packaging materials have the following characteristics: high tensile strength, high vertical and horizontal elongation, good puncture and tear resistance, strong fastening, and high degree of mechanization of stretch film, which is especially suitable for the secondary packaging of meat products. The packaged products are beautiful, safe and hygienic in circulation, and have been widely used in western countries. In recent years, they have also been widely used in larger meat products enterprises in China

with the development of social economy and the pursuit of consumers' quality of life, the relationship between meat packaging and people's daily life is increasingly close. Therefore, the Rockwell hardness of meat packaging materials and packaging technology is 0.001mm, which has a broad market prospect. Vacuum shrink packaging technology will be the development direction in the future; With the improvement of mechanization in the packaging of meat products, stretch film packaging technology will be widely used. Therefore, the research on meat packaging materials and packaging technology can not only enhance the added value of meat products, but also promote the progress of the whole meat industry

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