The Laboratory Notebook

Answering important questions about quality.

By Robert Green

Q. I bought some ginger extract overseas and the manufacturer claims that it is 6% gingerols. When we had it tested in the U.S., the total gingerol content was measured to be less than half that. What might the reason be and how can I get to the bottom of this?

A. First of all, you are not the only person trying to get to the “root” of this issue. Ginger has become increasingly popular in the U.S. and many companies are putting it to work in their supplements. The health benefits of ginger have been availed of in many countries for centuries, so it is not surprising that this has not gone unnoticed in the U.S. Not just for cleansing your palette at a sushi restaurant or a spice in your favorite dish, ginger is said to alleviate nausea, aide in digestion, have anti-inflammatory activity, and contribute to a healthy heart, to name just a few.

Since ginger is native to warmer climates, in the U.S. Hawaii is a significant producer. Most ginger in our industry is imported from Asia, primarily India and China. While currently there are no regulations re-quiring the testing of ginger, many buyers of this imported material be-lieve testing is particularly important. There are a number of reasons why this is a good idea. First of all, your supplier is far away. It is unlikely you have been able to visit, let alone conduct an audit of the facility from which you are buying the material. You may not even know who the true supplier is; just your immediate seller. As such, it is unlikely there is a relationship of mutual trust and respect that one can take comfort in. Second, if you buy a large amount of material and discover down the road that there is a problem, restitution will be difficult if not impossible. You need to protect yourself from the outset. Third, there may be a language barrier. Are you buying ginger extract or ginger powder? Finally, there appears to be a significant amount of substandard material on the market, so the buyer MUST be aware.

It is widely believed that the health benefits of ginger come from two families of components called “gingerols” and “shogaols” (specifically 6-gingerol and 6-shogaol). These, in turn, are part of the “oleoresin” family (or pungent substances). Identified gingerols present in ginger include gingerols 4, 6, 7, 8, 10 and 12 (with 6-gingerol being the main component). When ginger is dehydrated, gingerols become shogaols 4, 6, 7, 8, 10 and 12. But it doesn’t stop there! After gingerols become shogaols, they further degrade to zingerone.

When it comes to analytical testing, the term “gingerols” can be a slippery slope. That’s because there does not appear to be a consensus of what is included in the term “gingerols,” and this can greatly affect the analytical results.

So here is the issue. You and your analytical lab may not know exactly what your overseas supplier considered when they certified their product. Are they measuring only the true gingerols? Do they also include the shogaols? Maybe they are measuring zingerone as well. In our laboratory we have generally been testing for 6, 8, and 10 gingerol and 6-shogaol by HPLC. We use pure, external standards for each of these compounds, and to avoid any confusion we note that we are testing these four components on our reports.

With respect to your discrepancy, we would encourage you to contact the supplier. If you do not know what the supplier included in their total gingerol assessment, then it is difficult to align analytical results with product claims. This may be the problem. Go back and see if your supplier will tell you what they measured when they came up with the claim of 6% gingerols. Also, see if they will send you a copy of the analytical results supporting the claim. A chromatogram is a chromatogram in any language. If they give you viable data, you can at least be reassured that there is some basis for their claim. If your supplier comes back with additional components to the ones your lab tested for and those components are determined to be reasonable in defining the total gingerol content, then your lab may be able to obtain analytical standards against which to identify and quantify those additional components. This may close the gap between the results and the product claim.

If communication is good and there has been an effort on the supplier’s part to prove the legitimacy of their claim, then there may be another explanation for the failing results. As mentioned before, components of ginger, like most botanicals, are extremely fragile. Moisture, heat, and manufacturing may play a part in their degradation. It is possible that at one time it was 6% gingerols, but due external factors it became zingerone. It may be possible to determine what happened to the original components, but generally it is not worth the effort; either the product is now good or not.

In a nutshell, as we usually find in these analytical testing situations, the material that you imported may have failed for one or several reasons—your lab was not testing for the same components your supplier did when they assessed it as 6% gingerols, the analytes of interest may have degraded into other compounds, the lab re-sults may be inaccurate, or you may just have bad material. No matter what the reason, if you have honest parties who want to get to the “root of the problem,” proper analytical techniques will get you there. NW