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Rural Industries Research & Development Corporation
Production of High Quality Australian Ginseng
by R. B. H. Wills & D. L. Stuart
December 2001 RIRDC Publication No 01/170 RIRDC Project No: UNC-8A
American ginseng (Panax quinquefolium) is a medicinal herb native to the temperate regions of North America. It has found considerable usage in north Asia where Asian ginseng (Panax ginseng) has been a traditional medicine for many centuries. The accelerating affluence of many Asian countries coupled with the growing popularity of alternative therapies in the Western world has led to a marked increase in the international trade in both species of ginseng. The growth in ginseng trading has led to the establishment of an Australian industry based on the growing of American ginseng. While the industry is still in its infancy, it has created an umbrella organisation, the Australian Ginseng Growers Association (AGGA), which is promoting a national approach to industry development. Australia is agriculturally well positioned to capture a share of the world market and cropping is now conducted on organic principles in a wide range of regions across the eastern and southern States.
If Australia is to become successful at exporting and import substitution, it needs to resolve various marketing and quality issues. As traders and consumers become more sophisticated in their requirements for product quality, and the world crop supply increases to match, or as appears likely to exceed market demand, there will be greater competition in the ginseng market. Countries which have the reputation and ability to consistently supply high quality raw material and processed products will gain preferential access to the higher price market segment, thus maximising the economic return from the crop.
The ultimate determinant quality factor in all medicinal herbs, including ginseng, is the concentration of active constituents that impart a health benefit to the human body. While a number of groups of active compounds have been identified, it is widely accepted that the saponins known as ginsenosides, are major active constituents in ginseng. The research studies described in this report used the major ginsenosides of Rg1, Re, Rb1, Rc, Rb2, and Rd as the markers of ginseng quality.
The overall aim of the project was to assist the Australian growers to develop a marketing strategy for future Australian-grown American ginseng crops based on quality. The research objectives focused on determining: • reliable methods for the analysis of ginsenosides, • changes in ginsenosides in plant parts during plant growth and maturation, • effect of postharvest handling and processing operations on ginsenosides, • quality of ginseng products available in retail outlets, and • survey the situation and practices of Australian ginseng farms.
Efficient and reliable quantitative analytical methods for the analysis of both neutral and malonyl ginsenosides in American ginseng were developed using high performance liquid chromatography (HPLC). The importance of neutral ginsenosides is well known but relatively recently recognition of the importance of malonyl ginsenosides due to their potential hydrolysis to neutral ginsenosides has highlighted the need for both malonyl and neutral ginsenosides to be analysed in any quality assurance system established by the industry. In this project, the importance of malonyl ginsenosides was not recognised until after most of the growth trials had been completed and hence data for malonyl ginsenosides was mostly only obtained for the processing and storage trials.
The neutral ginsenosides in the various parts of 4-year old American ginseng plants grown in Victoria were determined at seven harvest periods over a whole growing cycle from leaf emergence to dormancy. It was found that ginseng roots contained a similar composition and concentration of neutral ginsenosides as roots grown in North America and Asia and should therefore be as acceptable in medicinal quality for the international market as American ginseng grown in other countries. In addition, the concentration of ginsenosides tended to be at the upper level of the range previously reported for American ginseng. The cultivation of ginseng under a canopy of eucalypt trees has thus appeared not to have a detrimental effect on the accumulation of neutral ginsenosides.
The concentration of the neutral ginsenosides over the growth period showed little change in the main root and lateral root. The highest concentration of ginsenosides was in the leaf and the hair root and in these plant parts, the concentration significantly increased to a maximum value at the growth stage when green fruit was present. The absolute amount of neutral ginsenosides in plant sections, the amount being a function of plant weight and ginsenosides concentration, showed that the main root and lateral root contained most of the plant ginsenosides due to their high contribution to total plant weight. The hair roots had the highest ginsenosides concentration but contributed only about 5% of the total ginsenosides due to its relatively low weight. However, the leaves when fully developed contained about 25% of the total ginsenosides from a high concentration and weight contribution.
The ginseng industry world-wide has traditionally marketed only the main and larger lateral root sections. The findings from this project suggest that utilisation of the leaves and, to a lesser extent, the hair roots, could generate a valuable by-product with beneficial medicinal properties. Commercial utilisation of leaf material would, however, require harvesting of the plant before the leaves started to senesce rather than at the current dormant stage. This would appear feasible since there was no reduction in the concentration of ginsenosides in roots if harvested at an earlier stage of plant development. The pharmacological activity of the two plant sections would appear to be similar as the composition of ginsenosides is not radically different between the leaf and root but this would need further investigation. An additional consideration would be to confirm that early harvesting of the leaf every year did not affect growth of the root. The harvesting of leaves would at least allow some return to growers before the root attained commercial maturity.
The determination of ginsenosides in roots of different age grown on a single site and of the same age but grown in different locations showed that for both sets of roots, there was a strong linear relationship between root weight and ginsenosides concentration. The findings suggested that it would be advantageous for the industry to identify growing practices or improved plant nutrition that increase the rate of root growth. The benefits to be gained would not only be an increase in root size but also an increase in ginsenosides concentration. While there was only a limited number of samples in the survey of roots from different farms, the results also suggested that field cultivated material under artificial shade produce a faster growing root and therefore a greater concentration of ginsenosides than forest-grown roots. This relationship needs to be explored further. In the farm survey, the malonyl ginsenosides were also analysed and the data show that in fresh roots the proportion of neutral to malonyl ginsenosides was in the ratio of 3:2. This factor could be useful in estimating the total ginsenosides in roots where the malonyl ginsenosides were not analysed.
Since the importance of managing postharvest handling operations in maintaining ginseng quality does not appear to have been extensively studied in other countries, there is an opportunity for Australia to gain a market advantage by retaining ginsenosides in traded products through improving such practices. The project examined the effect on ginsenosides of the drying of fresh root, storage of dried root, steam blanching of fresh root, alcoholic extraction of dried root powder and spray drying of the alcoholic extract.
A study was conducted to determine the effect of air temperature on the ginsenosides during the drying of fresh roots in a hot air drier. Increasing the drying temperature was found to cause a loss of malonyl ginsenosides, a small increase in neutral ginsenosides and a loss of total ginsenosides. The drying temperature should therefore be minimised to optimise retention of total ginsenosides. A drying temperature of 55ºC is recommended over lower temperatures due to the reduced drying time with little loss of ginsenosides. Drying at higher temperatures further reduces drying time but with enhanced loss of ginsenosides along with significant tissue browning. While there was no evaluation of other drying technologies such as heat pump, low pressure and freeze drying, it is suggested that these technologies would result in reduced loss of ginsenosides as they employ less heat during drying, but the equipments are much more expensive to purchase and operate.
Storage of dried ginseng root powder over the temperature range of 5° to 30°C was found to be temperature dependent. There was increasing loss of total ginsenosides with increasing temperature which was associated with an initial conversion of malonyl ginsenosides to the corresponding neutral ginsenosides. Optimum storage for dried material is therefore at low temperatures such as 5°C where no appreciable loss of ginsenosides occurred over three months. However, it would also seem prudent based on experience with other medicinal herbs, to use packaging that protects the product from absorption of atmospheric moisture and probably also light.
Steam blanching is a traditional method to produce the "red ginseng" from Asian ginseng root. No published studies are available to show the change in malonyl and neutral ginsenosides during the blanching of Asian or American ginseng but this study found a similar loss of ginsenosides with increased blanching time as with increased heat loading during drying. At the optimum blanching time of 2 hr which produces an attractive appearance for the red ginseng product, there was a loss of 15% in total ginsenosides which is considered acceptable. From a quality perspective, the production of red American ginseng is worthy of further investigation by the Australian industry.
The establishment of an Australian processing industry for ginseng requires an efficient method of extraction of ginsenosides and their subsequent concentration into a saleable product. Ethanol is a common, acceptable solvent used for the production of a wide range of extracts in the food and pharmaceutical industries. This project found that a relatively wide range of ethanol/water mixtures was able to extract about 85-90% of both neutral and malonyl ginsenosides. The use of 50% ethanol is considered to be the optimal concentration. The project examined spray drying as a representative method of concentrating the alcoholic extract. It was found that using commercially acceptable spray drying temperature regimes, the resulting dried product had a highly acceptable colour and texture with less than a 15%. loss of ginsenosides. It is considered that a market exists for the sale of dried ginseng extract for incorporation into other food or pharmaceutical products.
To examine the quality of ginseng products available to consumers, a range of dried and processed ginseng products were purchased from retail outlets and the concentration of neutral ginsenosides determined. Considerable variation was found to exist between products. This variation would arise from different amounts of added ginseng into a product and natural or induced variability between batches of raw material during postharvest operations. Unlike previous similar analysis on other medicinal herbs, there were no products with near zero levels of ginsenosides. However, each of the product classes contained varying concentrations of ginsenosides. The highest concentration was found in root powders and tea bags followed by the dry root and tablets/capsules. The higher values in root powders and tea bags probably reflect the use of hair and smaller lateral root sections which have a higher ginsenosides concentration. The wide range of values found for the tablet and capsules would reflect varying efficiencies of processing as well as variable quality of raw material. The variation within each product class does illustrate the need for growers and processors to exercise quality management of postharvest handling and processing operations in order to standardise on raw material inputs and minimise post-farm gate losses of ginsenosides. From a consumer perspective, the findings highlight the need for improved labelling of products. While many products do contain high levels of ginsenosides they cannot be identified by purchasers. Product labels should contain a more standardised format on ginseng content and include the concentration of nominated active constituents in the final product, similar to processed foods. This information should be supplied both on a unit product weight or volume, as well as on a recommended dose basis.
While this project was on quality management issues, interaction with the Australian and international ginseng industry has generated some ideas on how the Australian industry might develop. Since Australia can only be a small contributor to the international ginseng market, it would benefit from having a national ginseng brand and a national marketing and processing operation. This would allow the many small growers to equal access international markets with branded and guaranteed high quality products that could attract a price premium. Such an operation would further assist the economic viability of the industry by allowing the production of commercial products from non-root plant sections such as hair root and leaf. The existence of AGGA offers a ready platform that could develop beyond a grower consultative body to become the national marketing and processing organisation.
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