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A Stabilizing Force


Posting expiration dates on product labels is voluntary, but manufacturers that do so need to ensure that the product behind the label remains stable.

Among the many requirements of the dietary supplement good manufacturing practices (GMPs) in place for all manufacturers since 2010, the Food and Drug Administration (FDA) mandates testing data to support expiration or “use by” dates on product labels. Expiration dates per se aren’t a must under the GMPs, but if a manufacturer does include them, then it had better be prepared to say why when the time comes for a GMP inspection by FDA.

“While expiration dates are not required under GMPs, retailers generally require it and consumers expect it,” said Andrew Shao, senior vice president of scientific and regulatory affairs with the Council for Responsible Nutrition (CRN), last year when NSF International issued the voluntary Stability Testing Guideline for Dietary Supplements. “Firms should use science-based evidence to determine their product’s stability and this guideline can help direct industry on how to do so.”

Additionally, Shao said, “FDA officials have made it clear that if expiration dates are used, adequate stability testing data is expected and that they will pay attention to it during inspections, so firms should really do their due diligence to make sure their expiration dates are backed by science.” Shao was a member of the working group of trade associations and CRN member companies that Michigan-based NSF organized to help develop the guideline, reportedly the first of its type.

According to NSF, the stability Guideline specifies that companies understand the impact of manufacturing, packaging, labeling, distribution and holding/warehouse processes all may have on a product’s expiration. It suggests that dietary supplement companies identify the physical, chemical and microbiological characteristics under long-term storage. NSF said the guideline “helps dietary supplement companies be proactive and ensure their expiration dates are backed by sound science.”

The guideline also proposes that the stability testing be conducted in the same container that’s used for marketing the product. Among the factors involved in such testing are: dietary ingredient strength, chemical fingerprints, microbial growth, preservative content, moisture content, pH, viscosity and oxidation, as well as other parameters such as the product’s container-closure system.

A guidance document on certificates of analysis for dietary supplement components, issued by CRN in 2009, illustrates some of the considerations that go into ensuring the stability of products as shipped to stores. “The stability of components may be an important factor in the stability of the finished dietary supplements that contain them,” the document states. “Many components are very stable and may not require extensive testing to demonstrate continued conformance to appropriate specifications. Other components may undergo chemical, physical and/or microbiological changes over time that cause the material to fall outside established specifications.”

Further, according to the guidance document, appropriate expiration and/or recommended re-evaluation dates for components “should be established from the results of a documented stability-testing program, or from historical data. The testing program should include defined and controlled storage conditions (e.g., temperature and humidity), a consideration of different packaging types that may be used as market containers, and meaningful, specific test methods to adequately assess the stability characteristics of the component. Stability testing should determine whether possible degradation, moisture gain or loss, viscosity changes or other possible changes occur that render the component unacceptable for use (e.g., unstable or hygroscopic materials).”

Putting Into Practice

Not only are there quite an assortment of factors that can affect stability, getting a true reading is also a challenge. As Pittsburgh-based testing firm Microbac Laboratories Inc. explained, “A product’s shelf life is critical information for a manufacturer to know, but it can also be difficult to determine. Every product is different from a formula standpoint, is stored under different conditions and is used in differing ways.” The company seeks to define a customer-specific protocol, and then recreate as much as is feasible “the conditions required to provide the most reliable study possible.”

One way to help ensure product stability is through ingredients. For example, Glanbia Nutritionals in Wisconsin touts its flaxseed-based OptiSol 5000 for moisture control, shelf-life extension, viscosity generation and cryoprotection, along with enhanced nutritional benefits due to its naturally high content of alpha lipoic acid (ALA) omega-3 and fiber. When Glanbia introduced the latest in its OptiSol line earlier this year, it positioned the ingredient as a guar gum alternative in the face of reports of guar shortages; the extent of that shortage has been a point of contention as 2012 wore on, however.

Another example is the Descote line of microencapsulated products from Missouri-based Particle Dynamics International (PDI). Ostensibly designed to provide tasteand odor-masking, Descote can also provide stability enhancement by protecting unstable substances from air, light, water and reactive materials.

The secret, according to PDI, is a technology that yields “an enrobed particle that withstands the rigors of processing through blending and tabletting operations. This ensures that the final product will perform as required.”

A study published this summer in the journal LWT—Food Science and Technology also figured in nanotechnology, but with a twist. A team of researchers led by Dr. Mahua Ghosh from the University of Calcutta in India found that adding beta-cartoene and ALA to a nano-encapsulated lipid formulation enhanced the stable release of the lipid from the nano-capsules.

A chief drawback of bioavailable lipids, the researchers wrote, “is their extreme oxidation-prone nature, which subsequently affects the color, flavor, texture and, most importantly, the nutritional value of the lipid. This necessitates the development of a suitable measure to protect these sensitive lipids from deterioration.”

Earlier in the year, the journal Food & Function reported that Purdue University food scientist Srinivas Janaswamy had developed a method to help protect nutritional supplements from degradation. Janaswamy and former student Susanne Youngren used iota-carrageenan to encapsulate curcumin, which in turn was used to replace the water molecule “pockets” in the carbohydrate’s structure.

Published reports say that the researchers found that the iota-carrageenan network maintained a stable organization after encasing the curcumin molecules, protecting them from melting, and then releasing the molecules in a sustained manner.

Janaswamy reportedly sees a day in which such encapsulated fibers could be chopped into small particles; these would offer diners a way of adding supplements such as resveratrol or curcumin to their food, in the manner of seasoning it with salt or pepper.


■ Microbac Laboratories Inc., (412) 459-1060
■ NSF International, (800) 673-6275
■ Particle Dynamics International, (314) 968-2376

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