Application of carbon dioxide bacteriostatic technology in dairy products
Dairy products are ideal for a broad spectrum of microbiota because of their nutrient-rich nature. Therefore, bacteriostatic preservation is an important part of dairy product storage and even sales. Acidification and deterioration are the core factors leading to the deterioration of dairy flavor and the rise of bags. It is also a huge challenge for dairy preservation and storage technology. Experiments have shown that the acidification and deterioration of dairy products are not only the "personal performance" of the spoilage flora, but the joint action of the spoilage flora and its released extracellular enzymes. The main cause of deterioration of dairy products - microorganisms Most dairy products, such as pasteurized milk, yogurt, etc., need to be stored at low temperatures to maintain their good quality and nutrients. However, cryopreservation does not inhibit all microorganisms, such as psychrophiles. According to the literature, about 25% of the problems in the shelf life of all dairy products are caused by psychrophiles. The reproduction and growth of the chilling Gram-negative genus can deteriorate the microbial environment in chilled raw materials, pasteurized milk, skim milk cheese and the like. Pseudomonas is a representative strain of psychrophilic bacteria. It is a Gram-negative and anaerobic psychrophilic bacteria. These strains can not only grow in milk, but also release many extracellular degradable milk components. Enzymes, mainly including proteases and lipases. These two enzymes are capable of breaking down proteins and fats, causing sensory defects in the milk. These enzymes also have heat-resistant properties that affect the quality of the products made from pasteurized milk. Other common microorganisms, such as yeasts and molds, can cause flavor, texture deterioration and visible spoilage. In addition, the growth of heat-resistant lactic acid bacteria can lower the pH of pasteurized milk until a curd phenomenon occurs. Related studies have shown that fresh milk still retains a certain amount of microorganisms after pasteurization. Generally, after pasteurization, the growth of microorganisms is slow within 7 days, but with the prolongation of storage time, the number of psychrophilic bacteria mainly composed of Pseudomonas rapidly increases. When the storage time is 10-12 days, the number of Pseudomonas can reach a peak. At the same time, lactic acid streptococci and the like begin to rapidly multiply, and lactose is decomposed to produce lactic acid, which increases the degree of lactic acid, and the pH value continues to decrease. At this time, the growth of Pseudomonas is limited. After 12 days, Pseudomonas began to die in large numbers, and when the pH dropped to 5, the growth of Streptococcus mutans was also inhibited. Because Lactobacillus has strong acid resistance, it gradually takes advantage of breeding and continues to produce acid. At this time, a large number of milk clots appear in the milk, and whey is precipitated. Table 1 Application of carbon dioxide bacteriostatic technology in dairy products Bacteriostatic is a permanent topic in the field of storage and preservation of dairy products. The microbial flora mainly composed of psychrophilic bacteria still has strong reproductive ability in low temperature environment, and is the most important rot fungus group of dairy products. Carbon dioxide is a natural anti-microbial agent, which has the effect of inhibiting the growth of microorganisms. It can be used for the purpose of antibacterial preservation by directly adding carbon dioxide to dairy products and MAP modified packaging technology filled with carbon dioxide mixed gas. Carbon dioxide is the highest oxidation state of carbon atoms, and it exists in a colorless and odorless gas state at normal temperature, and is slightly soluble in water. It is a natural antimicrobial agent that has the effect of inhibiting the growth of microorganisms. Because the carbon dioxide molecule is a non-polar molecule, it is easily dissolved in the lipid bilayer of the microbial cell membrane and can increase the fluidity of the membrane, thereby exposing the cytoplasm to a toxic environment. The cytoplasm of the microorganism contains water, and the carbon dioxide reacts with water to form carbonic acid, which causes the pH of the cytoplasm to decrease and the pressure of the cell to increase. When carbon dioxide accumulates in the cells, the microorganisms need to consume more metabolic energy as a metabolic waste, and at the same time replace the oxygen to a minimum, a degradation reaction occurs, and the normal physiological balance of the microorganisms is disturbed. Carbon dioxide antibacterial technology is often used in two ways: Direct addition of carbon dioxide has been confirmed by studies that carbon dioxide has an inhibitory effect on the growth of Gram-positive and Gram-negative microorganisms. The effect of this inhibition depends mainly on the degree of solubility of carbon dioxide in the product, so liquid dairy products that are more soluble are more suitable for direct addition of carbon dioxide. When carbon dioxide is added, the cylinder containing the liquefied and compressed carbon dioxide is connected to the bottom of the liquid milk container by means of a pressure reducing valve and a conduit, and the liquid milk is filled with an appropriate amount of carbon dioxide at a lower pressure. This method has a significant effect on extending the shelf life of liquid milk, but direct addition of carbon dioxide is affected by the barrier properties of the packaging material. The packaging material is a barrier between the liquid milk and the external environment. Its main function is to block the oxygen which accelerates the oxidation of the milk. This property is generally characterized by the oxygen transmission rate of the packaging material, that is, the larger the oxygen permeability, the more oxygen per unit time passes through the same area of ​​the packaging material. It is well known that oxygen can promote the growth and reproduction of most microorganisms, which will lead to a significant reduction in the antibacterial effect of carbon dioxide. I have used the VAC-V2 differential pressure gas permeation instrument to test the oxygen transmission rate of various liquid milk packaging materials at different storage temperatures. As shown in Table 1, the oxygen permeability of the composite membrane is significantly lower than that of the PE membrane. This is because the composite membrane combines the advantages of various membranes, especially the composite membrane with the addition of aluminum foil, and the oxygen transmission rate is only the same. 0.05%-0.16% of PE film at temperature. Table 1 also reflects the fact that the oxygen permeability index of the packaging material is affected by temperature, that is, the higher the temperature, the greater the oxygen transmission rate of the material, and the more unfavorable the barrier to oxygen. Table 2 Based on the test results in Table 1, for liquid milk that uses direct addition of carbon dioxide to inhibit bacteria, the author suggests to use multi-layer plastic composite film, aluminum-plastic composite film, paper aluminum-plastic composite film or aluminized composite film as packaging materials, making full use of It produces synergistic bacteriostatic action. Related studies have shown that after injecting carbon dioxide into the raw milk, packaging with high barrier materials can increase the shelf life by 97.9%, while packaging with low barrier materials increases the shelf life by only 65.6%. MAP modified atmosphere packaging technology with added carbon dioxide mixed gas, also known as modified atmosphere fresh-keeping packaging, is a packaging form that regulates the gas content in the package to create an atmosphere that is conducive to antibacterial and fresh-keeping gas. Powdered dairy products are more suitable for MAP due to the form. Modified atmosphere packaging technology. MAP modified atmosphere packaging technology is to fill a certain proportion of nitrogen and carbon dioxide mixed gas into the package, the inert gas filled with nitrogen can minimize the oxygen residue in the milk powder package; carbon dioxide synergizes with nitrogen to inhibit the aerobic bacteria in the milk powder. , thereby extending the shelf life. It should be noted that the bacteriostatic effect of MAP modified atmosphere packaging technology is closely related to the stability of the content of various gas components in the package. If the package used for the milk powder has poor barrier to gas, or the milk powder package is not tightly sealed, it is easy to change the content of nitrogen or carbon dioxide inside the package. This is also the reason why milk powder modified atmosphere packaging requires the use of packaging materials with high barrier properties for gases, as well as the establishment of a routine monitoring mechanism for the periodic detection of gas content in packaging. The top air content of the milk powder samples of the canned milk powder and the aluminum-plastic composite film was measured by the CLASSIC 650 top air analyzer. The results are shown in Table 2. The canned milk powder is packaged in a gas-conditioned package filled with carbon dioxide and nitrogen. The content of each gas component during the test is relatively stable. The reason may be that the tinplate can itself has excellent barrier properties to gases. The aluminum-plastic composite film bagged milk powder is packed in nitrogen. It can be observed from Table 2. The oxygen content increases slowly with the storage time, and the nitrogen and carbon dioxide content gradually decreases. This may be because the surface of the aluminum-plastic composite bag exists. Pinholes or creases, or leaks, increase the amount of oxygen permeation throughout the package.
Moxibustion is one of
the oldest medical techniques in China. It uses the moxa produced by the
wormwood of the king of herbs to burn on the body surface or the affected
acupuncture points, warm-ironing, and infiltration of the pure yang-heating
medicinal gas by moxibustion. Force to warm the body's stimulation. Through the
conduction of meridians and acupoints to regulate the yin and yang balance of
the viscera, it is a therapy for the purpose of warming the meridians,
relieving the phlegm, spreading the cold, rejuvenating the cultivating evil,
preventing disease, and longevity.
The electric
Moxibustion Bed lights the moxa sticks on the tray as needed. The placement of
the moxa sticks is rationally distributed according to the height of the
person. The person lays on the moxibustion bed. When the swing function is
turned on, the moxa sticks back and forth behind the person. Moxibustion,
according to the person's ability to accept, press the button of the
controller, can adjust the ascending and descending of Ai Huo, and adjust the height,
so that the Ai Huo is always in an optimal position, which is beneficial to the
human body. You can easily lie on a moxibustion bed and you will inevitably
accept this rhythm and smooth, comfortable moxibustion treatment. This
multifunctional electric moxibustion bed can be used as a massage bed according
to your individual needs. Push the covers on both sides toward the middle to
close it. This way you can use it as a massage bed. You can enjoy it
comfortably by lying in bed. massage.
Function and Feature:
1. Automatic split
lifting temperature adjustment system
2. Automatic smoke
exhaust system
3 automatic swing
suspension moxibustion system
4 automatic ignition
system (a total of 12 automatic ignition devices, can be lit 12-24 Ai Zhuyi,
easy to use personal flexibility)
5. High-quality metal
structure steel bed frame, durable and beautiful
6. Environmental
protection PU leather bed, the bed bottom with high quality fireproof fabric,
in line with national fire safety standards
7. Electric lift system
+ rocking mechanism + exhaust system + control system
Moxibustion Bed Moxibustion Bed,Therapy Moxibustion Bed,Moxibustion Beauty Bed,Moxibustion Massager Bed MING MEI ROYAL SPA FURNITURE , http://www.mingmeibeauty.com