2.3. Sugar analysis
All standards and must samples were filtered through a 0.45 mm
PTFE membrane filter prior to HPLC analysis. The levels of glucose,
fructose, and sucrose were analyzed using a liquid chromatography
(LC) apparatus (LC-10Avp, Shimadzu, Kyoto, Japan) equipped with a
TSKgel amide-80 column (250 4.6 mm, 5 mm; Tosho, Japan) and a
refractive index (RID) detector. The column and detector were
adjusted to a temperature of 35 C. Twenty microliters of blueberry
musts and standards were injected into the column. Elution was
carried out at a flow rate of 1.0 ml/min with 75% acetonitrile as the
mobile phase.