Carbohydrate and Ginsenoside Changes in Ginseng Roots Grown in the Bay of Plenty, New Zealand

Abstract

Ginseng is traditionally cultivated worldwide in cold continental climates. It is now also being cultivated in maritime environments such as New Zealandis. This paper reports a number of growth and quality parameters for plants grown under those conditions over two growing seasons and the intervening winter dormant period. While shoot biomass peaked mid-summer, in contrast, root biomass peaked late autumn/early winter. Starch, sucrose, fructose, glucose and inositol were detected in the roots. Starch concentrations were highest in early autumn (mean 470 mg <TEX>$g^{-1}$</TEX> dry weight) and lowest in mid spring (218 mg <TEX>$g^{-1}$</TEX> dry weight). Sucrose concentrations were low during early summer until late autumn but increased rapidly with the onset of winter and peaked during mid spring (168 mg <TEX>$g^{-1}$</TEX> dry weight). Fructose and glucose concentrations were similar and peaked in late spring (5.3 and 6.2 mg <TEX>$g^{-1}$</TEX> dry weight). Inositol concentrations peaked in mid summer (1.7 mg <TEX>$g^{-1}$</TEX> dry weight). Starch/sugar ratios were high during summer and autumn and low during winter and spring. Ginsenoside concentrations and profiles showed that the six major ginsenosides, Rgl, Re, Rb1, Rc, Rb2 and Rd, were present, but Rf was absent. Concentrations did not vary with sampling date. The most abundant ginsenosides were Re (15.9 to 17.5 mg <TEX>$g^{-1}$</TEX> dry weight) and Rb1 (10.7 to 18.1 mg <TEX>$g^{-1}$</TEX> dry weight). Combined, they accounted for < <TEX>$75{\%}$</TEX> of total ginsenoside concentrations. Limited taste tests indicated that highest root quality occurred during late autumn, after the shoots had senesced. However, quality could not be related to plant chemistry.