The purpose of this paper is to discuss the various assay methods. The producer of the nutritional supplements or the consumer of the supplements need to have an understanding of the potency of the bromelain used and a means to compare Bromelain containing products. Bromelain has been approved for use in the U.S. since the early 70's. It is considered GRAS (Generally Recognized As Safe). Bromelain is also listed in the Canadian Table V, Food Additives that May Be Used As Food Enzymes. Much of the original work on Bromelain was done in the early 70's and 80's. Of particular interest are the papers by Dr. S. J. Taussig. There are numerous papers that are easily accessible via library or the internet which discuss the physiological properties of Bromelain.
There are a number of different assay methods used for Bromelain. These include the Gelatin Digestion Unit (GDU), the Casein Digestion Unit (CDU), the Milk Clot Unit (MCU), the Bromelain Tyrosine Unit (BTU), and the FCC Botanical Protease Unit. Each of the assays have their pros and cons. Each of these assays measure proteolytic activity, but not the same proteolytic activity. Each assay has a different substrate, gelatin, casein, non fat dry milk, and hemoglobin. The relationship between the various proteases measured can vary due to seasonal changes in the growing regions as well as time of harvest, distance to processing facility, etc. Therefore, the relationship between the various assay results will change. It is possible to have "rules of thumb". However, unless the assay is actually run, there is no guarantee of a particular activity. The FCC is the most consistent.
In overall terms of the consistency of results, the GDU will provide the most variability followed by the BTU, MCU, CDU, and finally the FCC with the least variability.
One of the reasons the FCC will give a consistent result, is that the FCC organization provides a control standard of known proteolytic activity. With a known standard, variables from experimental error due to substrate variability or a host of other factors, can be eliminated. EDC as well as other members of the Enzyme Technical Association are promoting the use of the FCC Botanical Protease Assay as a means of providing consistent information to the consumer.
Some people have tried to claim a relationship of 1 CDU to 2 GDU. As you can see, it is a " rule of thumb", but it is not accurate. For the Lot A of Bromelain the relationship is 1 CDU to 2.27 GDU and Bromelain Lot B the relationship is 1 CDU to 1.55 GDU. There has also been a relationship of 1 CDU per mg is equal to 1.2 MCU per mg. In Lot A, it is almost a 1:1 relationship and in Lot B, the relationship is 1.14 MCU per 1 CDU. One of the conclusions that can be drawn is that clearly Lot B met the required 2,000 GDU per gram minimum whereas the first Lot was clearly substandard. The check to prove this is the CDU assay. With a relationship of 2.2 CDU per GDU at a figure of 2,000 GDU per gram, the CDU per mg on Lot A should have exceeded 900 CDU per mg.
As a further service to consumers, it is highly recommended that both a specific activity and weight be listed on the label. For instance, a product containing 500 mgs Bromelain may contain a Bromelain testing 2,000 FCC Botanical Protease per mg or 20,000 FCC per mg. Unless the activity is listed on the label, the consumer would have no way of knowing that one is pure Bromelain and the other is mostly filler. As the producer and purchaser of the raw material, it is vital that your specifications include some type of activity requirement. This will allow your purchasing agent to make a reasonable comparison of offers.
Pricing would be very inexpensive (usually) for low activity Bromelain and very expensive for the high activity Bromelain.
Without direction, the purchasing agent is left to interpret the quality of the Bromelain required for the application.
A good analogy would be if the purchasing agent was told to buy a horse, if no other direction was given, the purchasing agent could end up buying a thoroughbred racing horse for hundreds of thousands of dollars, or a broken down quarter horse for a few dollars. In each case, the purchasing agent would have bought a horse and met the requirement as defined by the instructions.
By providing a purchasing agent with the required activity of any enzyme, you will avoid this problem. By putting the activity as well as the weight on the label, your consumers will have the information they need to make a good choice and will be able to promote the sale and purchase of high quality digestive aids.