Preservative method without or with less preservative
In the past few decades, the preservation of food has been achieved through the addition of preservatives. Although there are more than 20 kinds of preservatives allowed in food in China, the use of excessive amounts of harm to the human body has occurred from time to time. With the improvement of living standards, people pay more and more attention to the safety of food, and realize that the accumulation of preservatives also has great uncertainty on the long-term effects of the human body, and it is not completely safe. For example, daily cooked food products have a mixing ratio of fresh gas: about 65% nitrogen (N2) and about 35% carbon dioxide (CO2). When lychee and other fruits are kept fresh, the mixing ratio of oxygen (O2) is 5%; nitrogen dioxide (CO2) is 5%, and nitrogen (N2) is about 90%; it is worth mentioning that when selecting modified atmosphere packaging, It is necessary to take into account the barrier properties of the packaging material to the protective gas, otherwise the modified atmosphere packaging becomes a "rootless wood". These methods can effectively extend the freshness and shelf life of foods without or with the use of preservatives. It is hoped that these advanced scientific methods can be widely used to protect food safety and bring a safe to consumers. living environment.
Fortunately, the development and improvement of packaging new materials and packaging technology has made it possible to improve the use of preservatives. By improving the barrier properties of packaging materials and using air-conditioning (MAP)/air-conditioning (CAP) packaging, it is possible to achieve the effect of prolonging the shelf life of food by using no or less preservatives.
First of all, let's take a look at the main food safety issues that are common during the shelf life.
1, mildew:
This is a large-scale propagation of mold under sufficient oxygen and moisture conditions, which can cause changes in the smell, taste, texture and appearance of food, and can cause food toxicity. The foods that cause such phenomena are mainly wet products.
2, rancid deterioration:
The process by which the food itself gradually oxidizes to cause spoilage causes changes in odor, taste, texture and appearance, and leads to a decrease in the nutritional value of the food. The foods that cause such phenomena are mainly based on products rich in fats and vitamins, such as nuts. After long-term storage, the taste of the fats and oils that we are familiar with will appear.
3. Enzymatic browning:
The biochemical reaction of vegetable foods in the body's biological enzymes, temperature, oxygen and light environment has undergone changes in appearance such as color.
4, the taste is worse, the total number of colonies exceeds the standard:
Carbonated drinks, etc., due to the loss of carbon dioxide in the container, affect the taste, and the weak acid environment of the bottle is weakened, causing the proliferation of aerobic bacteria.
In response to the above phenomena, the latest packaging materials and packaging technology provide us with better protection:
First of all, for different products, the use of packaging materials with appropriate barrier properties can effectively block the infiltration of oxygen or water vapor, thereby preventing food oxidation, or breeding bacteria due to moisture; for carbonated beverages, it is necessary to effectively block carbon dioxide. Lost materials and containers.
Oxygen scavengers are also commonly used to prevent oxidation, but the material cost is high, and the safe packaging and labeling of oxygen scavengers is very important, otherwise the leaks will contaminate the food or be ingested by consumers.
On the basis of ensuring the barrier properties and sealing properties of the materials, the use of air-conditioning (MAP) / air-controlled (CAP) packaging will further extend the freshness and shelf life of the food. Modified atmosphere packaging is also a less expensive and safer method than oxygen scavengers. Air-conditioning packaging uses protective gas to replace the air inside the package. Commonly used protective gases are:
CO2: can prevent the growth of most bacteria and molds
N2: It can drive away air, prevent the growth of bacteria in high-humidity food packaging, and prevent the oxidation of high-fat foods.
O2: Maintain a fresh "natural" color, keep the fruits and vegetables breathing, and prevent the growth of anaerobic bacteria.
Therefore, depending on the actual needs, a certain gas may be used alone or in a certain proportion, and filled into the packaging of the food.