Look at the ingredient list
Oyster sauce, as the name implies, is made of oysters (oysters), so the word oyster juice will be in the ingredient list to be the real oyster sauce. According to the national food safety standards, the ingredients are arranged in descending order, so the position of oyster juice row is the better.
Look at the viscosity
Judging from the viscosity, good oyster sauce is sticky and can be hung on the wall.
Shake the oyster sauce up and down to see if it can stick to the bottle. If it can, it means it is high-quality oyster sauce. If the oyster sauce falls rapidly after shaking, it means that its viscosity is not high and its quality is not good.
Look at the color
Look at the bottom of the oyster sauce bottle. Through the bottle, you can see that the color of oyster sauce is reddish brown or brown, bright and shiny. This is high-quality oyster sauce. The color is dark and black, so don't buy it.