The reason why fermented rice becomes sour

Fermented glutinous rice is a popular food, and it can not only be eaten as a food, but also as a medicine. It has many benefits to people's bodies, such as promoting fluid production and quenching thirst, clearing away heat and relieving fire, promoting blood circulation and removing blood stasis, relieving dysmenorrhea and so on. The normal taste of fermented glutinous rice is slightly sweet. Some people may find that the fermented glutinous rice tastes sour. This may be caused by deterioration. Here we will introduce the reasons why fermented glutinous rice tastes sour.

What causes wine to become sour?

1. In the process of making sweet wine, it is an open operation. In such an operating environment, it is inevitable to come into contact with many other bacteria, the main one of which is lactobacillus. Lactic acid bacteria are anaerobic bacteria that use sugars to produce lactic acid. The growth of lactobacilli and yeasts showed antagonism. When lactobacillus grows in large quantities and produces lactic acid, the pH value of the mash decreases, causing the yeast to coagulate and denature, and eventually leading to the death of the yeast.

2. Acetic acid bacteria is also a major source of pollution. Oxidizes alcohol to acetic acid.

3. In addition to the above infection caused by careless operation, there is also the problem of not steaming the rice thoroughly, resulting in a low degree of starch gelatinization, which is not conducive to the growth of Rhizopus and affects the saccharification step. The direct consequence is that the fermented glutinous rice is not sweet. At the same time, certain bacteria that can directly decompose starch may also grow.

4. Of course, there are many factors that cause sourness, such as the quality of the koji, adding the koji before the rice has cooled, and the fermentation temperature... However, they are all the result of the activities of the above-mentioned "workers".

Can you still eat sour fermented rice?

The sourness of glutinous rice wine is usually caused by the reproduction of some putrefactive bacteria (such as lactic acid bacteria), which eventually produce organic acids such as lactic acid, acetic acid or citric acid in the wine. Theoretically, as long as these acids exist, no matter if they are diluted, sugar is added, or even re-fermented with new wine, it cannot make it completely sweet, but can only reduce the sour taste. If you want to continue eating it, you can add some sugar after it is completely boiled and it can still be eaten. These acids are not harmful to the human body (if it is left at room temperature for a long time and becomes sour, it cannot be eaten).