This is because when rice cakes are fermented, yeasts and other fungi propagate too fast, which causes the starch, sugar, protein and other substances in rice to decompose into substances with very small molecular weight under the action of enzymes, and finally into peptides and form organic acids, such as lactic acid, acetic acid, acetic acid, butyric acid, etc. These organic acids all have different degrees of sourness, so if rice cakes are fermented for a little longer, they will be sour.

If you want to make rice cakes with very low or no sour taste, you can grind the rice slurry, put it at room temperature for 15 minutes, then put it in a refrigerator at 8℃ for 1 half an hour, and then put it at room temperature for 20-30 minutes. This low-temperature fermentation method can not only inhibit the excessive growth of yeast, but also prevent the nutrients in rice from being too much. Moreover, the fragrance of rice can still be retained, and the rice cake made by this fermentation method is only slightly sour, and it is mixed with sweet and sour taste, forming a sweet and sour mouth, which is very delicious; Of course, if you don't like this taste, you can add a little baking soda to the rice slurry during steaming to neutralize the sour taste, so that the rice cake will no longer have sour taste.