Ensuring Safe, Microbial-Free Organic Ingredients
By Rupa Das
Over the last 25 years, the organic industry has grown tremendously and with it so has the spectrum of organic ingredients. This includes a wonderful variety of organic herbs, which have seen double-digit growth year after year. This strong growth trend is expected to remain on track for the next five years.
While this development of organic herbs has most certainly led to improved flavor profiles for organic foods and higher functioning supplements, ingredients such as herbs come with a whole new set of challenges processors must deal with in order to ensure both safety and quality. Although organic ingredients are far less likely to have pesticide residues or heavy metal contamination in comparison to their conventional counterparts— all agricultural products have microbial contamination and organic products are no different.
What Causes Microbial Contamination?
There are many ways that ingredients such as herbs can become contaminated; some are more easily controlled than others. With some plants, the inherent biological structure predisposes it to higher levels of microbial contamination. For example, nettle and sage leaves have trichomes (hair-like appendages) on their surfaces, which greatly increase the surface area exposed for microbial contamination.
Environmental conditions where the plant is grown and unsanitary collection and processing, drying, storage and transportation also contribute to microbial contamination. Both wild-crafted and cultivated sources of herbs are subject to microbial exposure.
The amount and type of microbial load also depends on the part of the plant used. For example turmeric root will have a higher and different microbial load compared to a seed product because the root will take up some types of bacteria from the soil. Some microbes such as E.coli and Salmonella are pathogenic and unsafe for human consumption.
Preventing and Eliminating Contamination
Good agricultural and collection practices (GACPs) in every phase of growing, harvesting and handling can minimize the microbial load. The World Health Organization (WHO) has developed guidelines on GACPs for medicinal plants. The guidelines provide a description of the techniques and measures required for appropriate cultivation and collection of medicinal plants and recording and documentation of necessary data and information during processing.
Some areas such as China, Japan and the EU have developed regional and national guidelines for GACPs of medicinal plants. Despite such guidelines, there is considerable disparity between knowledge and implementation. A majority of the herbs are grown and harvested in geographic regions where hygiene standards and facilities are either not adequate or not as stringent as some of the other parts of the world. Therefore, eliminating microbial issues through GACPs is still a goal that is yet to be achieved in most cases.
Hence, in order to reduce microbial load, eliminate pathogens and make ingredients safe and suitable for human consumption, agricultural products often require some form of sterilization.
Several different sterilization options are available in the food processing world, but, first and foremost, organic processors must make sure that the sterilization process chosen is compliant with organic regulations to ensure that the organic integrity of the material is maintained. Methods such as ethylene oxide (ETO) and gamma-irradiation are not allowed in organic due to negative health effects and long-term environmental impact linked with these practices. These are discussed below in “Not Allowed in Organic for Good Reason.”
Also, before deciding on a method, it’s important to understand the impact of sterilization processes on product integrity, efficacy and stability. Some methods may work well on one product, but then alter taste, color or other qualities of another type of product. Make sure to choose a method that works best for each product on a case-by-case basis. Commercial viability, governmental regulations and consumer acceptance can also influence the method chosen as well.
Below are some of the methods that have been approved for use in products labeled “organic” and/or “made with organic.”
Ozone. This sterilization method has a long history of use in numerous industrial applications as a disinfectant for wastewater treatment, aquaculture, beverage processing such as wine, milk and bottled juices and for water purification including drinking water. The bactericidal, fungicidal and general disinfection and oxidizing effects of ozone treatment are used worldwide to extend the storage life of various perishable food products. Treatment with ozone does not leave a residue in the product and thus can be used in certified “organic” and “made with organic” products.
Due to its strong oxidizing activity, it can destroy bacteria, mold or any other organic material. However, since agricultural products are organic materials, the over-use of ozone could partially oxidize the material being treated and cause quality changes in aroma, color and taste.
Ozone can be created synthetically with an ozone generator and can be applied in the gas as well as aqueous phases. Gas-phase ozone applied to stored agricultural products increases the storage life resulting in less product loss during storage. Aqueous phase ozone is being used in many food processing plants to spray or wash food products. It is used in garlic processing plants to reduce the microbial load in garlic. About a 1-log reduction of microbial load can be achieved with ozone application. Although a 1-log reduction may be sufficient for certain agricultural products, it may be insufficient for other dried herbal products.
Thermal and High Pressure. These can be used together to reduce microbial contamination and, since there are no chemical residues, it can be used for organic products. It’s considered a natural process and has the advantage of being able to process bulk products in their packaging. However, depending on the temperature and pressure used, it may impact the product integrity and efficacy. Generally, a 1-to 2-log microbial load reduction can be achieved.
Hydrogen Peroxide. This is an alternative to the conventional sterilization methods of ETO and irradiation. Like ozone, hydrogen peroxide is an oxidizing agent and has been used for water treatment and in processing ingredients such as onion and garlic. However, compared to ozone, hydrogen peroxide is a rather poor disinfectant and is not approved as a stand-alone treatment for microbial control in water systems. Its oxidizing properties could partially oxidize the material being treated and, therefore, affect the quality of the product.
Steam. This form of sterilization has gained immense popularity in recent years, especially for herbal dietary supplement products. The process involves treating dried plant based materials with high temperature steam under pressure. A 2-to 3- fold log reduction in microbial load, which is required for most herbal dietary supplement products, can be achieved using this sterilization method. To illustrate the effectiveness, a shipment of organic dandelion root was recently held at port by the FDA for presence of Salmonella, but using steam sterilization, it was able to be reconditioned. The product was saved and released into commerce after thorough testing.
Steam sterilization does not involve the use of any chemicals and thus is an approved method for organic products. However, it is important that the temperature and pressure of the steam process is customized for each individual product in order to maintain the integrity and efficacy of the treated material. If not done correctly, it could lead to moisture gain and mold growth in the product.
Closing Thoughts. Overall, when considering various methods of treatment available for microbial load reduction, several factors need to be considered. Other than cost, the integrity and efficacy of the resulting product should be taken into account. Manufacturers of organic products should also look for methods that can offer long-term shelf life stability of the sterilized products. Instant microbial reduction with chance of microbial regrowth later is not acceptable.
Lastly, a majority of the herbal dietary supplement products, as well as a wide range of functional foods and beverages, are marketed for their antioxidant properties. Sterilization methods used to treat such products should be selected so as not to compromise the antioxidant effects of such products.
As consumers become more educated, acceptance of different treatment methods is evolving to a point where there is a greater demand for products (and processing methods) that fulfill their increasing requirements for health and safety without compromising quality or efficacy. Using the proper sterilization method results in better, safer products and happier customers.
Rupa Das, is the vice president of global quality and regulatory compliance at BI Nutraceuticals, which specializes in herbal powders and extracts (www.botanicals.com). She has over 16 years of quality and regulatory compliance management experience in the dietary supplement and personal care product industries. Das is also a certified good manufacturing practice (GMP) auditor and is involved with leading industry organizations such as the American Herbal Products Association (AHPA) and the Association of Analytical Communities (AOAC) International. You can contact her at firstname.lastname@example.org.