When lauric acid was introduced into the 6-position hydroxy group of 1,5-GL by lipase by Pocalyko et al., the initial compound synthesized was the one in which the 6-position hydroxy group of 1,5-GL was esterified. This compound decreases with time, and an increase in the compound has been reported in which the 6-position hydroxy group of 1,4-GL, which cyclized at 1,4-position, is esterified.