Friends who have studied chemistry know that nitrogen molecules are very stable and difficult to react with other substances. Because of its chemical inertness, nitrogen is widely used in the food industry. As a commonly used food additive, nitrogen is found in almost all kinds of fast food to pastries, from bottled water to various beverages, but it is low-key that it does not enter the list of food ingredients.

1. The bag is filled with air, just to look good?

When you eat puffed foods such as french fries, you will find that there are not many things in the bag but it is bulging. Is it that the merchant fills the bag with air to reduce the content and reduce the cost? Neither nor nor. The bags are filled with food-grade nitrogen gas instead of air for the following purposes:

The first is to extend the shelf life of food. We know that oxygen in the air can accelerate the oxidation process of food and promote the life activities of microorganisms, so it is an important factor leading to the oxidation and spoilage of food. Nitrogen-filled packaging can effectively remove oxygen, thereby inhibiting the oxidation of food and the reproduction of microorganisms.

Second, nitrogen filling can resist the invasion of external moisture. The positive pressure environment created by nitrogen-filled packaging can prevent the internal food from getting wet and delay the deterioration of the food.

Third, nitrogen filling also protects food from being crushed. Snacks like potato chips are crisp and fragile, and packing them in nitrogen-filled bags is equivalent to being equipped with a gas buffer, which solves the problem of brittleness during storage and transportation.

2. In an extremely cold world, why make food "splendid"?

The boiling point of nitrogen at normal pressure is -195.8°C. When it is in contact with the frozen food, the latent heat of evaporation that can be absorbed is 198.9kJ/kg; then the nitrogen vapor is heated to -20°C, and the average specific heat is 1.047kJ/kg. (kg·K), it can absorb 184.1kJ/kg. The total of the two is 383.0kJ/kg, which is an ideal refrigerant.

During the 2018 World Cup, Chinese crayfish stole the show. "Drinking beer, eating crayfish, watching the World Cup" is undoubtedly a super experience. 100,000 crayfish were transported through the cold chain (minus 18 degrees Celsius), creating the miracle of Chinese crayfish rushing to the World Cup in June. And the hero behind the creation of this miracle is the liquid nitrogen freezing technology. The seasoned crayfish is quick-frozen in liquid nitrogen to minus 190 degrees Celsius. The crayfish that have undergone the "extreme cold" test can be quickly locked in freshness and have delicious meat. Just thaw and reheat after shipping to Russia.

When freezing, refrigerating and transporting food, the low temperature performance of liquid nitrogen has been brought into full play. The use of liquid nitrogen to preserve seafood is also the use of liquid nitrogen freezing technology. In recent years, people have also tried to apply liquid nitrogen to food production. For example, smoking ice cream is made by mixing ice cream ingredients and edible liquid nitrogen. The extremely cold liquid nitrogen quickly vaporizes and absorbs heat when it encounters the air, causing the surrounding water vapor to condense into small water droplets, resulting in a "smoky" effect. As a legal food processing aid, there is no "exceeding standard" problem in the application of food-grade nitrogen in food. However, the temperature of liquid nitrogen is extremely low, and people are prone to frostbite when eating foods with liquid nitrogen added. Therefore, experts suggest that consumers should avoid direct contact with liquid nitrogen.

3. Why do you need a "drop" for canned beverages?

In bottled and canned beverages, dripping food-grade liquid nitrogen is a relatively common practice. At 21°C, 1 cubic meter of liquid nitrogen can expand to 696 cubic meters of pure gaseous nitrogen. Taking advantage of this property of liquid nitrogen, dripping liquid nitrogen into the beverage filling process (accurate quantification is required) can form a certain internal pressure to support the tank.

This is beneficial for both storage and transportation. For cans and plastic bottles, dripping liquid nitrogen can make up for the soft texture of the can (bottle). The application of drip liquid nitrogen in the beverage industry enables the use of thinner and lighter materials for beverage packaging, saving manufacturing costs. In addition, instilling liquid nitrogen in beverages can extend the shelf life of the product. For non-carbonated beverages, instillation of liquid nitrogen removes air from the headspace inside the can (bottle), extending product shelf life and maintaining beverage color, flavor, and freshness.

4. What kind of enjoyment is nitrogen filling in drinks?

At the Tsingtao Beer Festival, a nitrogen-infused beer stood out. So what's so special about nitrogen-infused beer?

Give this beer a shake and it will turn black after sitting for a while. When the can is opened, the "nitrogen plastic ball" placed in the can will release nitrogen gas from the inside, resulting in a fine and soft foam, which is smoother and more delicate than carbonated foam... mellow bitterness and coffee Very similar, almost like a cup of "cappuccino".

Speaking of the fate of nitrogen and beer, this is definitely not an impulsive "Lalang match". Nitrogen beer was invented 60 years ago by Michael Ash, a scientist at the Guinness Brewery in Dublin. Now, nitrogen has been widely used in beer brewing and has played an important role. However, the gas in nitrogen beer is not nitrogen to rule the world, carbon dioxide also plays a role. Generally speaking, the filling gas in nitrogen beer is a mixture of 70% nitrogen and 30% carbon dioxide.

So, what role does nitrogen play in beer? Nitrogen not only prevents oxidation of the wort, but also improves the foam properties of the beer. Since nitrogen is insoluble in water, the resulting air bubbles do not float like carbon dioxide.

The gust of nitrogen when the nitrogen beer is uncapped also produces a sizzling sound and is more likely to produce a smooth and rich taste. At the same time, nitrogen can improve the stability of beer flavor and reduce the color of beer, but it will not affect the taste of beer. This is because nitrogen is an odorless, tasteless, colorless and chemically inert gas.

Today, nitro coffee is also popular at home and abroad. The so-called nitro coffee is the addition of high-pressure nitrogen to cold brew coffee. It not only retains the flavor of coffee, but also has a flexible foam and a mellow taste, which makes people enjoy the taste and vision.

Finally, a point to be reminded is that according to my country's food additive regulations, nitrogen can be used as a processing aid in various food processing processes without labeling, and the residue does not need to be limited, but the nitrogen used must meet the national food additives standard.