There are two types of soybean sprouts: one with longer sprouts and another with very short sprouts, which are in the initial stage of germination and are called small bean sprouts.
Small bean sprouts are likely soybean sprouts that have been germinated for about a day, while the longer ones are probably germinated for 3 to 4 days. Small bean sprouts have a more tender texture, a suitable length, and no off-flavor.
Compared to 3-4-day-old soybean sprouts, small bean sprouts contain higher levels of vitamin C and dietary fiber, but slightly less protein. Overall, the 1-day-old small bean sprouts are considered a premium product.