Talking about edible packaging materials and their applications

Packaging is very important for the quality of the food and for extending the shelf life. The principle of choosing food packaging materials is mainly to reduce the permeability of food storage. For example, composite plastic materials (PETîž„ALîž„LDPE) can play a role in blocking moisture and gas, but such packaging materials cannot be eaten at the same time as foods, and packaging wastes cannot be naturally degraded, which will cause environmental pollution. As human beings pay more attention to the living environment, scientists have been devoted to the research of edible packaging materials since 1990. Edible packaging material can not only be eaten together with food, but also can avoid environmental pollution and meet the needs of the green revolution. It is a welcome new packaging material.
Edible coating technology has been used in food for a long time. As early as 800 years ago, China used wax to coat the outer skin of citrus to prevent dehydration and preservation. In the 19th century, sucrose coating was used abroad to prevent oxidative rancidity in almonds and walnuts, and sucrose was used as an edible protection. Coated film; In the 1930s, wax, oil and water emulsions were sprayed on the surface of fruits to improve their appearance (such as color, hardness and brightness), control the maturity of fruits, and delay the escape of fruit moisture; later they adopted edible properties. Polysaccharides, such as alginate, cellulose ester, pectin and modified starch, are used to improve the quality of frozen and refrigerated meat. In the 1990s, scientists studied the range of edible packaging materials including aroma components, antioxidants, antimicrobial agents, pigments, browning reaction terminators, and vitamins. At present, there is a definitive proposal for edible packaging materials: Where film, flake, thin layer packaging or coating become part of food and it is edible, it is called edible packaging material. Edible packaging materials should be classified as food ingredients or food additives. If edible packaging material can increase the nutritional value of food, it is a food ingredient; otherwise it is regarded as a food additive. It can thus be seen that the classification of edible packaging materials is entirely dependent on its own use characteristics. Edible packaging materials should be as tasteless as possible or match the taste of the food. Although edible packaging materials have barrier properties against water vapor, air, and solute penetration, it is also necessary to add a layer of outer packaging in consideration of factors such as ease of carrying and hygiene. The choice of edible packaging material depends on the characteristics of the food being coated: For storage of fruits and vegetables, selective membranes must be used to facilitate the respiration reaction (exchange of gases such as oxygen, carbon dioxide, and ethylene), and to prevent water loss and solute. Infiltration; For oxygen-sensitive foods such as polyunsaturated lipids, low oxygen permeability membranes must be selected.
Edible packaging materials must meet the following conditions:
Excellent sensory characteristics; high barrier properties and a certain mechanical strength, with anti-biochemical, physical and microbiological stability, non-toxic and food safety, simple to use, does not pollute the environment, raw materials and manufacturing costs are low.
The main basis for the selection of edible packaging materials is the food needs protection and storage conditions. Sugars, proteins, lipids or mixtures thereof can all be used as formulations for edible packaging materials. Edible packaging materials are used in various types of foods such as meat and poultry, aquatic products, fruits and vegetables, confectionery, and cereals.
Colloidal films are used on fresh and frozen water livestock and poultry meat to delay the loss of moisture on the meat surface. The use of alginate gel-calcium chloride film on the surface of mutton can effectively inhibit the growth of microorganisms; on beef, it can maintain its color, flavor and appearance basically no different from fresh beef within 4 days. The use of a mixture of seaweed gum and a starch mixture can keep the steaks, pork chunks, and peeled chickens well organized and juicy. Collagen, casein, and cellulose derivatives can be used to coat membranes on meat or fish and reduce over-absorption of the product when fried. The use of alginate gel with cellulose derivatives and lactic acid (or acetic acid) or bacteriostatic agents on meat slices can reduce the growth of microorganisms. The casings used in traditional sausages have been gradually replaced by collagen or cellulose edible films.
After fruits and vegetables are harvested, they are mainly controlled by gas exchange during maturation, storage, or prevention of mold growth. Wax coatings, such as mineral oil, paraffin wax, beeswax, shellac, carnauba wax, etc., are coated on the surface of fruits or vegetables to control the respiration of fruits and vegetables. These fruits and vegetables include: mandarin, lemon, grapefruit, apple, pear, cherry, banana, mango, litchi, peach, grape, melon and carrot, cucumber, sweet potato, potato, pumpkin, eggplant, bell pepper, tomato, celery, radish, Asparagus and so on. Wax or oil can be used alone, or mixed in the emulsification system, or mixed in the protein solution. They all have good barrier properties to water and can effectively prevent the loss of moisture in fruits and vegetables. It must be noted that the wax can not be too thick, otherwise Will affect their breathing instead of accelerating aging. At present, excellent edible films have been developed to reduce the oxygen permeability and increase the evaporation of carbon dioxide and ethylene, which can effectively control the maturation of fruits and vegetables. For example, films of proteins, polysaccharides, and lipid mixtures have a permeation ratio of 10:1 to 25:1 for CO2 and oxygen, and a 5:1 ratio for plastic packaging. Zein is coated on the surface of tomato, and sucrose polyester coating on the surface of apples can delay color change, weight loss and hardness change. The oligosaccharide coating is a good fruit bacteriostatic agent and has excellent selectivity for moisture and gas. For example, coating on strawberries is not only a good bacteriostatic agent, but also makes its respiration rate optimal and effective. Prevent the loss of water from strawberries. The coating of oligomeric pectin or cellulose derivatives prevents rancidity caused by oxidation of nut oils. The film composed of starch, animal glue and calcium chloride can inhibit the non-fermenting browning of peeled potatoes. Many fruits, such as grapes, almonds, bananas, mangoes, pineapples, etc., due to high sugar content, easily form wet stick Phenomenon, and when it absorbs moisture, it will spoil, so it can be coated with wax, cellulose derivatives, starch, pectin and protein mixture to solve the above problems.
Candy can easily absorb moisture, stick, and cake, so it must be prevented by an edible coating. Milk, whey protein, cellulose derivatives, or waxes can effectively reduce the exudation of oil and water. "Only dissolves in the mouth and does not dissolve in the hand." Methyl cellulose membranes prevent whitening of chocolate candy; films made from a mixture of corn gluten and ethanol, coated on candies can reduce the drying time; double layers of wax and hydrophilic colloids can improve chewing gum Viscosity and reduced moisture loss extend shelf life.
The mixture of stearic acid palmitic acid and hydropropyl methylcellulose is used in tomato paste to reduce the water-off phenomenon caused by the transfer of water without altering the organoleptic properties of the product; use of methylcellulose and palm The acid-formed bilayer membrane allows the crispy skin of sundae ice cream to have a crunch for more than 3 months. (From 2000.11.15 "China Packaging News" Qi Qimei)