Look at the formula of raw materials: Tete oyster sauce, soy sauce ratio 1.6%, oyster sauce ratio 6.25%, salt 8. 12%, caramel 0.3%. Look at additives: ultra-polar oyster sauce, yeast extract content of 0.87%, sodium cyclamate content of 0.09. Look at the color: Kit's color is brown to reddish brown, bright and shiny, with a lasting fragrance. After pouring out, it is moderately viscous.

1. According to the formula of raw materials, the proportion of special oyster sauce and soy sauce is 1.6%, oyster sauce is 6.25%, salt is 8. 12%, and caramel pigment is 0.3%. The proportion of oyster sauce in secondary or tertiary oyster sauce will be lower than 6.25%, while that in primary oyster sauce will be 5%.

2. Look at additives. The content of yeast extract and sodium cyclamate in special oyster sauce is 0.87% and 0.09, respectively. Compared with the first and second grade, the yeast extract in Tete oyster sauce accounts for more, and the scallop extract is also higher than the first and second grade.

3, look at the color, this can be seen intuitively, especially the color is brown to reddish brown, bright and shiny, and the aroma is relatively lasting. After pouring out, the viscosity is moderate, smooth and uniform, without delamination and without any precipitation and impurities. First-and second-grade oyster sauce, the color will change from reddish brown to dark brown, the aroma is relatively light, and it has the umami flavor of oyster sauce.

4. According to its physical and chemical indexes, amino acid nitrogen, the index of special oyster sauce will be greater than or equal to 0.35/g( 100ml)- 1, the first-class index will be greater than or equal to 0.25/g( 100ml)- 1, and the second-class index will be greater than or equal to 0.35/g. The total nitrogen index is greater than or equal to 0.7, and the second and third grade oyster sauce is greater than or equal to 0.5 and greater than or equal to 0.4.