Changes in the Content of Pectic Substances in Tea Leaves (Camellia sinensis L.) during Steam Processing of Green Tea

Abstract

We examined the change in the content of pectic substances in tea leaves during the steaming of green tea. In four cultivars of tea leaves, water-soluble pectin (WSP) content increased with steaming time, whereas the dilute hydrochloric acid soluble pectin (HSP) content remained almost constant. A β-elimination reaction proceeds throughout the steaming process, so it was postulated that some water-insoluble forms of pectin in HSP convert to a water-soluble form via β-elimination degradation with increasing steaming time. When tea leaves were steamed, pectin fractions with a molecular weight of 1,100 × 10³ were degraded from water-insoluble HSP and eluted as WSP. Additionally, as steaming time increased, the fraction of smaller molecular weight pectin increased.