Combating Moisture and Humidity in Nutraceutical Packaging

Combating Moisture and Humidity in Nutraceutical Packaging

by Robert Crossno

The dollars spent researching, engineering and marketing nutraceutical products are wasted if these products are damaged by moisture during warehousing or transport. Discoloration, odors, and product deterioration are just a few of the damaging consequences caused by moisture contamination. Therefore, a manufacturer needs to think about how to guard against moisture damage when designing and producing a product package.

Desiccants

Desiccants are one of the most popular and well-known devices for protecting against moisture damage. They are cost-effective tools that help maintain the integrity of products by keeping them safe from moisture throughout the frequently arduous course of shipping and storage. Desiccants are available in various configurations: packets, bags, canisters, tablets, tubes and desiccant stoppers.

Desiccants act to scavenge and adsorb any ambient moisture in the package, any moisture released by the product itself and any additional moisture caused by condensation. Desiccants can also be inserted into a product's cap or injected into the product container itself through a process called injection molding, which provides moisture protection while guarding against accidental ingestion by consumers. Desiccants used in manufacturing applications are typically one of three materials: silica gel, molecular sieve or activated clay.

Silica gel is a non-toxic, non-corrosive form of silicon dioxide synthesized from sodium silicate and sulfuric acid and processed into granular or beaded form. Its active, interconnected pores form a vast surface area that attracts and holds water through adsorption and capillary condensation, allowing it to adsorb up to 38 percent of its weight in water vapor. While silica gel works most effectively at room temperature and high humidity levels, its potency is somewhat diminished at lower humidity levels of 30 percent and below.

On the other hand, molecular sieve contains a uniform network of crystalline pores and empty adsorption cavities. A synthetic desiccant derived from sodium, potassium or calcium crystalline hydrated aluminosilicates, its pore size can be controlled in the manufacturing process, allowing for a large range of adsorptive capabilities in the finished product. Molecular sieve can reduce ambient humidity to nearly 0 percent below detectable levels, but it must be handled in a controlled low-humidity environment prior to insertion to prevent loss of capacity.

The third option is activated bentonite clay. This is a naturally occurring, non-hazardous and salt-free substance that is the least expensive and most widely used desiccant material. The layered structure of activated clay attracts and adsorbs moisture onto its surface and between its layers. Activated clay has essentially the same capacity as silica gel at humidity levels between 25 percent and 30 percent. However, unlike silica gel, activated clay is still effective at levels of 20 percent humidity and below and can adsorb up to 20 percent its weight in water.

Whether product or product packaging has hygroscopic (water absorbing) properties, manufacturers of nutraceutical products can benefit greatly from desiccants. The choice between silica gel, molecular sieve or activated clay is ultimately based upon the ambient temperature and relative humidity product and product containers will experience.

Choosing the Right Desiccant

In weighing the various choices of desiccant materials, it is important to consider the ambient environment within the package in relation to the desiccant's individual capabilities. The key parameters are initial humidity, amount of moisture in the packaged product, volume of product and volume of container, Moisture Vapor Transmission Rate (MVTR), length of storage time, activity curve of the desiccant and the maximum level of relative humidity (RH) permitted within the enclosed package. Humidity levels and temperature can fluctuate drastically during shipping, causing the desiccant materials to respond differently to these variables. Consequently, manufacturers should consider all variables when formulating comprehensive moisture-protection programs.

Once the appropriate desiccant has been chosen, it is important to consider other factors that will aid in creating a product package that is the least susceptible to moisture damage. For example, a barrier pack made of foil (usually aluminum) or plastic (typically polyethylene) can protect product from external elements by preventing moisture from entering into the package and compromising product integrity. Effervescent tablets and nutraceutical tablets, such as vitamins, are frequently packaged in foil or plastic. Polyethylene plastic cylinders injection molded with desiccant are the latest method of protecting effervescent tablets against moisture damage. Nutraceutical tablets packaged in plastic or glass bottles can also be protected by the inclusion of canisters or packets containing desiccant.

Protection in the form of activated clay in Tyvek^® (a DuPont registered trademark) bags can save manufacturers millions of dollars in lost product and insurance expenses. Use of a simple psychometric chart can help calculate the number of adsorbent bags of activated clay needed under specific conditions.

Also known as a refrigeration chart, a psychometric chart displays readings for wet and dry bulb, relative humidity, temperatures and pressures. Once the temperature and humidity inside the container are known, these calculations enable the shipper to utilize a precise number of moisture-adsorbing bags.

In any product shipment, the inclusion of a humidity indicator card can allow for fast, hands-off, visual inspection of the package when it arrives at its final destination. When enclosed in a package, a humidity indicator card detects humidity levels caused by defective or improper packaging or other unintended exposure that otherwise might go unnoticed during shipping. The end user is alerted to the level of RH (relative humidity) in the package when the card shows pink to reflect damage or blue to reflect an uncompromised product. In the longrun, the card helps prevent corrupted product from damaging the manufacturer's reputation.

No matter which moisture inhibitor method is used, desiccants protect against moisture damage to the product and product packaging, and are non-toxic as well as environmentally friendly.

Nutraceutical manufacturers should keep in mind certain criteria when selecting a desiccant supplier. The supplier should:

Robert Crossno is the national sales manager for Belen, N.M.-based Süd-Chemie Performance Packaging. For more information on packaging options, visit www.s-cpp.com.