Guava is not ripe yet. According to relevant public information, if guava is immature, the pulp contains more tannic acid and a lot of organic acids. Immature guava tastes sour and astringent, and the dietary fiber structure in immature guava is relatively stable, which will increase the digestive burden of intestinal tract after eating, which is not conducive to health. Mature guava tastes much better, so guava is sour because it is raw.