Foodstuff Cloud: Running on the ground is not as good as flying in the sky, and flying in the sky is not as good as swimming in the water

The main thing swimming in the water is fish. Compared with the pig, beef and mutton that people usually eat, eating more fish is more beneficial to health.

In China's Dietary Guidelines for Chinese Residents, it is also recommended that people eat fish twice a week or 300~500 grams of fish and meat a week, averaging 40~75 grams a day.

However, according to the data in the Scientific Research Report 2021 of the Dietary Guidelines for Chinese Residents, only 25.6% of Chinese adults' daily intake of fish and shrimp reached the standard or above in 2018, and 74.4% of Chinese adults' daily intake of fish and shrimp was less than 40g/day. In terms of the intake of livestock and poultry meat, the proportion of people aged 18~44 years who consume more than 75 grams of livestock and poultry meat per day is relatively high, which is more than 58%.

Therefore, most of us should pay attention to that the diet can increase the intake of fish and shrimp, while reducing the intake of some livestock and poultry meat.

This article will talk about why we recommend you to eat fish and how to make it delicious. Finally, we will teach you how to choose fish.

What are the benefits of eating fish?

Most fish are light white, which is related to the growth environment of the fish. The fish live in water and swim every day, so it takes a long time to finish. Water will also produce buoyancy and resistance to fish. The faster you swim, the greater the resistance. Therefore, fish also need to have enough power to accelerate. Therefore, fast white muscle fibers that need to reserve emergency energy occupy the majority of muscle mass, mainly to facilitate sudden acceleration. Some fish will have more red meat on their bodies, which are generally fish that can swim for a long time in one breath and have more pink muscle fibers on their bodies.

Terrestrial organisms mostly rely on oil to store their physical strength, while fish rely on protein in their muscles to store their physical strength. Therefore, fish meat contains more protein, generally 15%~22%, and is also a high-quality protein with high absorption and utilization rate.

At the same time, because fish live in water all year round and need their bodies to keep normal operation even at 0 ℃, their fat structure is very long and irregular, containing more unsaturated fatty acids, mainly n-3 series. Especially the fish living in the sea are more abundant. This fatty acid plays an important role in human health, which is related to the health of brain and retina, cardiovascular and immune system.

The diet rich in n-3 series polyunsaturated fatty acids has anti-inflammatory effect, which can reduce the blood cholesterol level, inhibit the formation of thrombus, and reduce the risk of heart disease and cancer.

Some studies have shown that taking more fish can reduce the risk of all-cause death, stroke, middle aged and elderly dementia and cognitive dysfunction.

In addition, the content of vitamin A and vitamin D in the liver of fish is also rich, which can promote the absorption and utilization of calcium by the body, and is also beneficial to the health of the eyes, and can prevent night blindness.

When is the best time to eat fish?

The livestock and poultry meat that people usually eat will take several hours to reach the mature stage after slaughter, and the mature stage is the most delicious. The fish is different. The fish ripens quickly after slaughter and tastes better after a short period of time. Some fish will taste more delicious just after the stiff period, which is about 8~24 hours after death. However, if the stiff period is over, the fish will be easy to deteriorate. This is why many restaurants have "live fish to kill".

03 What happens when fish is heated during cooking?

When fish is heated during cooking, its texture, smell and color will change, which makes cooked fish look more appetizing than fresh fish.

① Change of fish color:

The meat of fish and shellfish is transparent when they are fresh, and will change from transparent to white due to myoglobin denaturation after being heated.

The shrimp and crabs are different. The shrimp and crabs generally have a cyan appearance when they are fresh, which is caused by the combination of astaxanthin and protein into a pigment protein.

The protein denatures after heating, and astaxanthin is oxidized to astaxanthin, so it will become red.

② Changes in the texture of fish:

With the increasing temperature during cooking, the texture of fish is also changing, in addition to its color. When the temperature is higher than 60 ℃, the muscle tissue will contract, the water content will continue to decline, and the hardness will increase.

The meat of fish is fragile and will be spoiled if you are not careful. This is because the muscle of fish is of layered structure, which presents a "W" shape layer by layer. The content of connective tissue is small, so it can not maintain the shape better. During the heating process, the collagen in the connective tissue of the fish will start to decompose at 50~55 ℃, making the muscle of the fish begin to layer and become piecemeal.

Therefore, the fish should be cooked gently and not for too long. If the heating time is long, it will not only cause the fish to be old and hard, but also easily make the fish fragmented. A piece of 2.5 cm thick fish can be cooked for about 10 minutes. The thicker part of the meat can be cut diagonally every 1~2 cm to improve the problem that the uneven thickness of the fish affects the ripeness.

Some people have done cooking experiments on bream. 500 grams of bream can be fully cooked after being heated in a 100 ℃ steamer for 8 minutes, and the texture is just good. If the bream is salted with proper amount of salt, the meat can be completely cooked after steaming for about 9 minutes under the same heating conditions, and the meat is soft and tender.

When cooking the fish, you can first slice the fish into medium sized fish chops, put the fish chops into the pot before the heated soup is about to roll, then turn off the fire, add a little cooled boiling juice, make the temperature in the pot drop to 65~70 ℃ (thermometer can be used), cover the fish chops and let them slowly mature inside.

③ Change of fish smell:

Most people's impression of the smell of fish is "fishy". In fact, the smell of extremely fresh fish is not mainly fishy, but like the smell of plant leaves after juice extraction. Almost all fish meat will carry an aroma molecule, which can emit a strong fragrance of geranium leaves, as well as a little metal flavor. Freshwater fish will carry the fragrance of "newly cut grass" and earth flavor.

Earthy flavor mainly comes from earthy flavor, which is concentrated in fish skin and dark muscle tissue. Generally, vinegar or other sour condiments can be used to decompose it.

The fishy smell mainly comes from trimethylamine, which is because trimethylamine oxide produced by fish in order to balance the salt concentration of seawater meets the bacteria on the fish body and is decomposed into fishy trimethylamine.

If you want to remove the fishy smell, you can first wash the fish with clean water, which can wash off the trimethylamine on the surface of the fish. Then pickle it with acidic condiments such as vinegar and lemon. They can provide hydrogen atoms to bind trimethylamine, which can bind with water and other molecules. In this way, when we eat fish, the fishy smell will not be sent into the nose.

Although fresh fish generally tastes fishy, cooked fish will have a unique flavor due to the interaction of fatty acids, oxygen molecules, amino acids and other substances after heating. Fresh fish contain more nucleotides, which will show a delicious taste when heated. The contents of volatile acids, nitrogen compounds and carbonyl compounds in cooked fish have increased significantly. These are volatile components, so we can smell an attractive aroma.

Fish and meat processed by grilling, frying, smoking, etc. will have a better flavor. If you also brush the sauce while roasting the fish, the ethanol, soy sauce, sugar and other substances from the sauce will also participate in the heating reaction. In addition, the various amino acids and oligopeptides produced by the heating hydrolysis of fish protein will make the overall smell better coordinated, prominent, and taste better, fresh and rich.

04 What fish do you suggest?

Although it is recommended that people often eat fish, not all fish can be eaten. In particular, marine fish may have heavy metal pollution. The amount of pollutants in fish meat is related to their eating habits and living waters. Large predatory fish at the top of the marine food chain have higher toxin content.

In addition, pregnant women, pregnant women and young children should avoid eating large or predatory fish, such as tuna (especially big order tuna and bluefin tuna), gold snapper, shark, swordfish, swordfish, snapper orange and mackerel, because the content of heavy gold methyl mercury in these fish may be higher than that in other fish.

How to choose a good fish?

If you want to eat delicious, nutritious and safe fish, you need to be more careful when shopping for fish. It is recommended to purchase according to the following four points:

① Look at the scales: the scales look fresh and shiny, close to the fish body and not easy to fall off, just like armor. This is a fresh fish; However, if the fish is not fresh, the scales will lose luster, loose and easy to fall off, and not compact.

② Look at the fish gills: the gills of fresh fish are clean, bright red, free of mucus and odor, and the gill cover and mouth are tightly closed; The gills of fresh fish are dark red, grayish red, or even green or white. The mucus is increased and has a fishy smell. The gill cover is loosened and the mouth is open.

③ Look at the eyes: the eyes of fresh fish are bright and protruding, with clear black and white; However, the eyes of the fish that are not fresh are collapsed, their eyes are turbid and have white membranes.

④ Press the fish body: the fresh fish body is not sunken, elastic, and feels hard when pressed by hand. The soft part of the meat can recover immediately after pressing, and the fish belly does not swell;

However, if the fish is not fresh, it will feel soft and sticky when it is pressed by hand. The soft part will not recover after pressing, and the belly will swell and protrude due to the effect of bacteria propagation.

In addition, if you choose live fish, those who are lively and responsive are the best. Those who are slow or floating on the water may be dying fish.
It is good for health to increase the intake of fish properly, but it is recommended not to eat fresh sashimi, but also to eat less grilled fish and fried fish. Because, fresh water fish may be contaminated by parasites and bacteria when making sashimi, while grilled fish and fried fish may produce carcinogens.

reference:

[1] Chinese Nutrition Society. Dietary Guidelines for Chinese Residents [M]. People's Health Publishing House. 2022

[2] Harold Markey Translated by Lin Huizhen. Food and Cooking. Milk · Egg · Meat · Fish. Beijing Fine Arts Photography Press. August 2013

[3] Zhou Xiaoyan Cooking Technology [M] China Textile Press, 2008

[4] https://www.fda.gov/food/consumers/advice-about-eating-fish

[5] Food Safety Center of the Hong Kong Special Administrative Region Government https://www.cfs.gov.hk/sc_chi/multimedia/multimedia_pub/multimedia_pub_fsb_201404.html