Research progress of the hottest antibacterial act

Research progress of antibacterial active packaging film

the active meaning of active packaging is that the packaging material has the functions of antibacterial, deoxygenation, dehumidification, ethylene removal, flavor release and absorption. Antibacterial packaging film is a kind of active packaging materials. It is mainly made of natural macromolecular substances as the carrier, adding certain antibacterial agents. Compared with ordinary packaging, antibacterial packaging plays a more prominent role in ensuring food safety and prolonging food shelf life. In order to promote the rapid development of antibacterial activity packaging in China, this paper summarizes the research progress of antibacterial activity packaging at home and abroad in recent years

1 antibacterial mechanism and influencing factors of antibacterial active packaging film

in terms of antibacterial mechanism, the current antibacterial packaging film mainly realizes its function through direct antibacterial or indirect antibacterial. Direct antibacterial is to add some substances with antibacterial function directly into the carrier to make a film. This kind of film will continuously release antibacterial substances to the food surface in contact with it to realize the anti-corrosion of food; Indirect antibacterial is to add some substances that can adjust the microenvironment in the packaging into the carrier or use the selective permeability of the packaging film to adjust the microenvironment in the packaging, which is not conducive to the growth and reproduction of microorganisms, so as to achieve the purpose of antibacterial. For the former, the commonly used antibacterial agents include food preservatives, antibiotics and lysozyme, which are the most widely studied and used antibacterial packaging films; For the latter, its antibacterial function is often achieved by adjusting the gas composition and temperature in the package

there are many factors that affect the antibacterial effect of antibacterial packaging film. In order to ensure the effectiveness of antibacterial packaging, the following factors should be fully considered when using antibacterial packaging. First of all, it is necessary to fully estimate the main susceptible and harmful flora, quantity and their growth characteristics of the packaged food. This helps to select the type and quantity of antibacterial agents used in antibacterial packaging, or the most effective microenvironment regulation index in packaging, and also helps to accurately estimate the effect of antibacterial packaging and the packaging life of food. The antibacterial capacity of antibacterial packaging is limited, so the packaged food is required to have the lowest possible initial pollution; Secondly, the choice of carrier materials also has a very important impact on the function of antibacterial packaging film, which mainly depends on the biological characteristics of the carrier. Its compatibility with antibacterial agents or microenvironment regulators and the permeability of the packaging film itself. The research shows that the slower the diffusion of antibacterial agent in the film, the better the antibacterial effect of the film; Moreover, the stability and timeliness of active antibacterial agents or microenvironment regulators added to antibacterial packaging and the stability of packaging film to the environment or food also have an important impact on the actual use of antibacterial packaging. Of course, choosing manufacturing materials with high safety, low price and easy access is a favorable condition for food antibacterial packaging to enter the market

2 classification of antibacterial active packaging film

the carrier of antibacterial packaging film is mainly some substances. According to the different properties of carriers, antibacterial membranes can be divided into hydrophilic colloidal, lipid and composite antibacterial membranes. The carrier of hydrophilic colloidal membrane is mainly white matter and polysaccharide, the carrier of lipid membrane is mainly wax and acyl dry oil, and the composite membrane is a combination of hydrophilic colloid and lipid as the carrier

1) antibacterial film with hydrophilic colloid as carrier hydrophilic colloidal antibacterial film is the most widely studied antibacterial packaging film, which can be divided into protein film and polysaccharide film according to different carriers

(1) protein antibacterial film

the food proteins of common antibacterial packaging film carriers include soybean protein isolate, corn gliadin, wheat gluten protein, sorghum gliadin, whey protein, peanut protein, etc. the advantages of this kind of film are edible, non-toxic, good stability, low permeability of oxygen and carbon dioxide, and its disadvantages are poor barrier ability to moisture in the air, It is easy to absorb moisture and cause food infection. The film made by adding 0.05mm0l/100ml ferulic acid to the membrane solution of soybean protein isolate has low permeability to water, carbon dioxide, oxygen and nitrogen in the environment, which can effectively change the microenvironment in the package and inhibit the growth and reproduction of harmful microorganisms. Rhim et al. Showed that adding sodium SDS sulfonate to the plasticized soy protein isolate membrane can effectively improve the ductility and moisture resistance of the membrane, thereby inhibiting microbial pollution and reproduction caused by moisture absorption of food in the package. Dawson et al. Found that the type of carrier protein and the way of film formation have a significant impact on the release of antibacterial properties nisin from antibacterial packaging film. The wheat protein film or zein film added with nisin has a certain inhibitory effect on La CT 0ba ciliu splantamm1752. Compared with zein film, the high-resolution structure of sorghum can be reorganized and fixed into arbitrary shape after printing, and the zein film has higher moisture resistance. Taylor et al. Pointed out that glacial acetic acid and lactic acid are good solvents for sorghum gliadin. The film made of the formed solution has a certain inhibitory effect on a variety of bacteria

(2) polysaccharide antibacterial film

common polysaccharides that can be used as antibacterial film carriers mainly include starch and its derivatives, cellulose and its derivatives, alginate, carrageenan, chitosan and agar. Polysaccharide antibacterial membrane is not only non-toxic, but also has the ability of selectivity and passing through carbon dioxide and oxygen. It can effectively reduce the respiration of fruits and vegetables and delay their aging, but its disadvantage is its poor barrier ability to water. Packaging fresh strawberries with starch film mixed with potassium sorbate can not only reduce the number of harmful microorganisms, but also extend the storage period from two weeks to four weeks. The antibacterial film with carboxymethyl cellulose as the carrier can reduce the water loss of fresh cut fruits, inhibit oxidation, delay maturation and inhibit microbial growth, so as to prolong the storage life of fresh cut fruits. In addition, bacteriocin was added to the antibacterial membrane with cellulose as the carrier. For example, nisin or pianococcus can selectively inhibit the growth and reproduction of some microorganisms, especially for Listeria

chitosan coating has obvious antibacterial and fresh-keeping effect on chilled pork, which may delay the decay of vacuum packaged refrigerated meat. 1. The minimum elongation of 10 inches (250mm) after copper rod heating, smelting or annealing is 30%. Pranto et al. Found that chitosan membrane mixed with garlic oil, potassium sorbate and nisin can significantly inhibit the reproduction of Gram-positive bacteria (Staphylococcus, Listeria and bacilli) in meat products. Ouattara et al. Found that when meat products are packaged with chitosan film mixed with acetic acid and propionic acid, acetic acid and propionic acid will be continuously released from the film, inhibiting the growth and reproduction of spoilage bacteria on the surface of meat products, so as to achieve the purpose of stabilizing quality and extending shelf life

pranoto et al. Found that sodium alginate membrane added with 1% garlic oil can significantly inhibit the growth of Escherichia coli, Salmonella and Staphylococcus. In addition, the tensile strength and ductility of the film were also improved by adding garlic oil. Fierd et al. Found that adding glucose oxidase to sodium alginate film can prolong the duration of sensory acceptable state of fish, delay the appearance of putrefaction taste, and then extend the shelf life of fish. The experiments showed that agar membrane containing antibiotics (such as chlortetracycline and neomycin) could effectively prolong the shelf life of segmented poultry stored at 2 ℃

2) antibacterial active membrane with lipid as carrier

according to the research of cauegarin et al., the membrane with lipid as carrier has the greatest advantage of high barrier performance to water. They also pointed out that the factors affecting the water barrier performance of lipid membranes mainly include the structural saturation, chain length, existing state, crystal form, crystal size and dispersion rate of lipids. Wax, fatty acid and acyl dry oil can be used as the carrier of lipid antibacterial activity membrane, among which wax is the most widely used. In the European Union, beeswax, wax slipper flower wax, carnauba wax and insect paint can be used as membrane preparations for food surface. These natural wax membranes can well reduce the loss of water and aroma in apples, rotten fruit rate and the chance of being infected by mold, ensure good taste and appearance of apples, and prolong storage time, Ensure that consumers can also eat apples with the same quality assurance in out of season

3) composite antibacterial active membrane

composite membrane integrates the advantages of hydrophilic colloidal membrane and lipid membrane, and is the future development direction of active packaging membrane. For example, the carriers with different properties of protein/lipid and polysaccharide/lipid composite membrane are mixed with each other. Due to the interaction between them, we can achieve the effect of learning from each other and further improve the packaging function of the membrane. For example, by adding beeswax, palmitic acid, stearic acid and lauric acid to the hydrophilic colloid, the barrier ability of the membrane to water can be greatly enhanced. Bertana et al. Added Brazil olive balm, glyceryl acetate, stearic acid and palmitic acid to white gelatin to make a composite film. Its moisture resistance is significantly improved, which can improve the humidity of the microenvironment in the package, so that some microorganisms that are not resistant to drying cannot survive, so as to achieve the purpose of indirect bacteriostasis and ensure food safety

3 antibacterial agents commonly used in direct antibacterial packaging films

the antibacterial agents used in direct antibacterial packaging films mainly include organic weak acids (propionic acid, acetic acid, sorbic acid) and PTMC, an aliphatic polyester elastomer, its salts, lysozyme, antibiotics (including bacteriocin) and some natural products with antibacterial activity

with methylcellulose as the carrier, potassium sorbate can be added to prepare films with excellent antibacterial properties, and the dissolution rate of potassium sorbate in the films is very slow. However, two problems should be paid attention to when preparing antibacterial packaging film with organic weak acid as antibacterial agent. First, different organic weak acids have different effects on the mechanical properties of packaging films. Caner et al. Showed that the tensile strength of chitosan membrane with lactic acid was about 5O% lower than that with other organic acids, while the extensibility of the membrane was about 80% higher. Second, the antibacterial effect of organic weak acids is good at low pH, and the antibacterial effect is significantly weakened or even disappeared when the pH is higher than a certain value

lysozyme and bacteriocin are the research hotspots of antimicrobial agents at present. Adding lysozyme to the carrier can produce an antibacterial packaging film that can effectively inhibit the growth of gram-positive and negative bacteria. It is reported that the antibacterial membrane made by adding bacteriocin nisin to cellulose can completely inhibit single-cell Listeria

in addition, the release rate of nisin in various hot pressed polymers combined with nisin was also determined. It was found that the chitosan membrane prepared by the expansion method, which will also further enhance the popularity of casting, has the highest release rate of nisin. Laticin3147 is a newly discovered Lactobacillin with broad-spectrum antibacterial properties. Amalia et al. Packaged cheese and ham with cellulose film mixed with nisin and laticin3147 can reduce the number of Listeria in ganku and ham by 2 orders of magnitude, and the number of Staphylococcus in ganku and ham by 1.5 and 2.8 orders of magnitude respectively. Using natural products with antibacterial activity as antibacterial agents to prepare antibacterial packaging film is a highlight of recent antibacterial packaging research. Grape seed extract is a typical example, Cha et al. Infiltrated grape seed extract into the membrane with sodium alginate as the carrier and found that this membrane can inhibit the activity of gram-positive and negative bacteria. In addition, essence from many plants, garlic extracts and allyl isosulfur from cruciferous vegetables