Foods are rich in protein, carbohydrates and fatty nutrients, in the physical, chemical and biological role of the flash element, you can lose the original color, smell, taste, shape and degeneration, which harmful microbial role Is the main cause of deterioration of food.
Before the industrialization, people use dried, salted, sugar, fermented and other traditional methods to save food; modern food industry development, people use a lot of new technology to save food, such as the use of cans, vacuum packaging, inflatable conditioning, packaging And other packaging methods to preserve food, but also the use of a variety of sterilization techniques, such as autoclaving, radiation sterilization, electron beam sterilization, storage generally used refrigeration, frozen, etc..
But no matter what kind of technology, can not ensure that foolproof, so for most food, the use of preservatives as the second line of defense to ensure that food shelf life is particularly important.
First, the preservative of food preservative mechanism
Preservatives are a class of compounds that inhibit microbial proliferation or kill microorganisms. Preservatives can prevent food in the storage, circulation process by microbial reproduction caused by deterioration, improve food preservation, to maintain the excellent quality of food and nutrients, to extend the food consumption value.
The standard for the development and selection of Preservatives is "high efficiency and low toxicity", high efficiency refers to the inhibition of microbial effect is good, and low toxicity refers to the human body does not produce observable poison. Although the basic metabolic processes of organisms have many similarities and similarities, the metabolism of each type of organism is very different. Generally, all kinds of substances are directly involved in the cellular response through the microbial cell membrane, and any physiological metabolism Interference of the material can interfere with the growth of microorganisms. So many substances on the human body without any adverse effects, but the great impact on the growth of microorganisms, due to the structural characteristics of different types of micro-organisms, metabolic methods are different, so the same kind of preservatives on different microbial effects are not the same.
Preservatives to suppress and kill the mechanism of microbial is very complex, the current use of preservatives on microbial mainly in the following aspects:
1) preservatives destroy the microbial cell membrane structure, or interfere with the synthesis of cell walls, or change the permeability of the cell membrane, so that the microbial organisms to escape the extracellular, or affect the membrane-related respiratory chain electron transport system, leading to normal physiological balance of microorganisms Be destroyed and inactivated;
2) preservatives acting on the microbial organisms, inhibit enzyme activity, interfere with its normal metabolism. Such as preservatives and enzymes thiol role, destruction of a variety of sulfur-containing protease activity, interference with the normal metabolism of microorganisms, thus affecting its survival and reproduction. Usually preservatives acting on the microbial respiratory enzymes, such as acetyl-CoA condensation enzymes, dehydrogenases, electron transfer enzymes and so on;
3) the role of preservatives in genetic material or genetic particle structure, thereby affecting the genetic material replication, transcription, protein translation;
4) other effects: including the role of preservatives in the protein, resulting in protein partial denaturation, protein cross-linking and lead to other physiological effects can not be carried out.
Generally speaking, a preservative is only a specific colony to kill or inhibit the effect, so, for the following considerations, it is necessary to carry out the formulation of preservative compound research.
1, broaden the antibacterial spectrum: some kind of preservative for some microbial effect is good and other microbial effect is poor, while the other preservative just the opposite. The two together, will be able to achieve broad-spectrum antimicrobial control purposes.
2, to improve efficacy: two different mechanisms of sterilization preservatives share, the effect is often not a simple superposition, but the multiplication, usually in the case of reduced use, still maintain sufficient bactericidal effect.
3, anti-secondary pollution: some preservatives on the mold rot fungi kill better, but the residual period is limited, while the other class of preservatives to kill the effect is not big, but the inhibition is significant, the two mixed, both To ensure the quality of storage and shelf, but also to prevent the use of repeated pollution in the process.
4, to improve safety: a single use of preservatives, and sometimes to achieve the anti-corrosion effect, the amount should be more than the required allowable amount, if a variety of preservatives in the allowable amount of mixing, both to achieve the purpose of prevention and control, but also to ensure product safety Sex.
5, to prevent the generation of resistance: If a microorganism on a preservative easy to produce resistance, then it is more than two kinds of preservatives are also resistant to the chance of naturally much more difficult.
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