Modified atmosphere packaging keeps seafood fresh

Modified atmosphere packaging keeps seafood fresh

With the improvement of people's living standards, consumers' demand for chilled meat is also increasing. However, due to the short fresh-keeping period of chilled meat, it is difficult to maintain the color and luster, and many enterprises are discouraged from this; to large-scale production and distribution of chilled meat, solving the problem of fresh-keeping is the key to improving the quality of chilled meat.

Composite modified atmosphere fresh-keeping packaging is also known as gas replacement packaging, and internationally known as MAP packaging (Modified Atmosphere Packaging). The composite modified atmosphere fresh-keeping packaging machine replaces the air in the packaging box by using the composite fresh-keeping gas mixed by 2-4 kinds of gases in proportion, changes the external environment of the food in the box, inhibits the growth and reproduction of bacteria and microorganisms, thus prolonging the The shelf life and shelf life of food. Compared with frozen food and vacuum-packed and high-temperature sterilized food, products packaged with modified atmosphere packaging machine technology have high fresh-keeping quality and good nutritional content, and can truly maintain the original juice and taste of the food itself.

The modified atmosphere fresh-keeping gas used in the composite modified atmosphere fresh-keeping packaging technology is generally composed of carbon dioxide, nitrogen, oxygen and a small amount of special gases. Carbon dioxide gas has the effect of inhibiting the growth and reproduction of most aerobic spoilage bacteria and molds, and is the main bacteriostatic agent in fresh-keeping gas; oxygen can inhibit the growth and reproduction of most anaerobic spoilage bacteria, maintain the color of fresh meat and maintain aerobic respiration of fresh fruits and vegetables. , the role of maintaining freshness; nitrogen is an inert gas, and it does not work with food. As a filling gas, it forms a composite fresh-keeping gas with carbon dioxide, oxygen and special gases.

1. Traditional low temperature preservation

Extending shelf life is extremely challenging for seafood merchants (due to the varying elemental content of different seafood products, the packaging that merchants need to preserve them varies widely). In general, seafood products such as fish, shrimp, and shellfish contain very small amounts of sugar, which allows bacteria in their gut and gills to quickly affect proteins in their tissues. The high water content of seafood makes their tissues pH neutral. A neutral environment is conducive to the survival and violent reaction of bacteria and enzymes, making seafood perishable. Fatty fish, such as herring and mackerel, are oxidized in the air and give off a foul odor. So for fish, we usually use low temperature treatments close to zero degrees Celsius to extend their shelf life.

2. Modified atmosphere preservation

With the popularity of modified atmosphere packaging machines, seafood products also use modified atmosphere packaging to extend the shelf life. Using the correct refrigeration methods and sophisticated modified atmosphere packaging can extend the shelf life of raw fish and seafood from just a few days to two to three years. week.

Ⅰ. For raw fish, more than 20% (usually close to 50%) carbon dioxide has a significant effect on inhibiting aerobic bacteria. This carbon dioxide dissolves in the water, making the bacteria's environment acidic, reducing their activity.

Ⅱ. Although oxygen has the effect of preserving the color of meat. For fatty fish, we usually do not add oxygen to modified atmosphere packaging in order to prevent the fish from going rancid.

Ⅲ. The packaging of prawns is generally only filled with carbon dioxide and nitrogen.

A major challenge for seafood merchants using modified atmosphere packaging is: what kind of gas environment can effectively inhibit the growth of bacteria. Since some bacteria are aerobic bacteria and some bacteria are anaerobic bacteria, it is difficult for merchants to find the balance point of oxygen and carbon dioxide content in the package if there is no sophisticated testing equipment in the design of modified atmosphere packaging.

Humans at the top of the food chain prefer red meat, poultry, and seafood, so the growth of modified atmosphere packaging is conceivable. In addition, the contemporary increase in demand for fresh fruits and vegetables and ready-to-eat food is also driving the growth of the global market for modified atmosphere packaging machines. Despite the large-scale use of modified atmosphere packaging, researchers are trying to develop active modified atmosphere packaging machines according to consumer needs, which are more environmentally friendly and improve the quality of packaged products.

The modified atmosphere fresh-keeping packaging machine replaces the atmospheric environment with a certain proportion of mixed fresh-keeping gas, which can prolong the shelf life of food. However, if there is a lack of understanding of the principle and application of the modified atmosphere packaging machine, it may cause long-term and imperceptible major economic losses. We know that under the same storage temperature and gas environment, the quality of food is basically the same. However, if the storage temperature is the same and the gas environment is different, the quality status and shelf life of the food will be very different. In the process of food modified atmosphere fresh-keeping packaging machine, we require that the proportion of fresh-keeping gas in each batch of packaging should be consistent, and the error of the proportion of fresh-keeping gas in each package should be ≤ 1%, so as to ensure that the same time and the same temperature can be guaranteed. In the case, the quality of the food remains the same.

On the contrary, if the proportion of fresh-keeping gas between each batch of packaged food is quite different (≥1%), the fresh-keeping period of the food will be very different from the shelf life, and the same batch of food can be kept fresh for 10 days and 6 days respectively. days, 3 days, etc. This will cause the manufacturer to be unable to grasp and control the quality status of the product, and can only use the shorter preservation time (such as the preservation time of 3 days) to control. The result of this will result in the original quality of fresh food (such as fresh-keeping time of 10 days and 6 days) and the food that is on the verge of spoilage. This is also known as the "barrel theory" in food modified atmosphere packaging machines. Gas is an invisible and intangible substance. It is difficult for us to distinguish the difference between fresh-keeping gas and air with the naked eye. The precise and consistent proportion of fresh-keeping gas can only be controlled and guaranteed by modified atmosphere packaging equipment. To avoid the occurrence of the "barrel theory", to maximize the benefits of food modified atmosphere packaging machines, to ensure the long-term interests of food production enterprises, and to choose stable, reliable and accurate packaging equipment, it is an important task for food manufacturers. This is an important work related to the development of the enterprise.