Will lemon juice not sour if it is left for a long time?

No, lemon tea or lemon juice may become bitter if it is kept for a long time, especially when it is fully ripe. In this case, the glue is "bitter". The peel and pulp of citrus fruits contain citrate lactone A ring (called LARL), which is used to synthesize limonin. LARL itself has no bitter taste, but it destroys the tissue structure of the fruit after extrusion. When it is acted by limonin hydrolase in acidic fruit juice, LARL will be quickly converted into limonin. However, for fully mature citrus fruits, limonin glycosides are formed under the catalysis of limonin glucosyltransferase as the fruits mature, thus preventing bitterness.