The sterilisation of spices, herbs and vegetable seasonings:

Understanding the options

The spice of life
Spices, herbs, seeds and dehydrated vegetable substances bring a world of flavours, aromas and colours to food.
Harvested in the rural reaches of places such as India, China and Indonesia, spices and herbs develop their flavors and fragrances by fermenting in the sun, drying in the open air, and through processing techniques such as roasting and grinding.
Once the appropriate flavours and aromas have been attained, the flavouring agents are shipped to brokers around the world using methods of transportation ranging from open barges to refrigerated trucks.
Unfortunately, during their long journey to the table, spices and herbs become contaminated with bacteria and molds. Bacterial contamination may come from soil, insects, bird or rodent droppings or from the water used in processing. Fungal growth may occur before or during drying, or during storage or shipping.
In any event, the consequences can be significant.

The risk of contamination

Bacterial contamination
Bacteria such as Bacillus cereus and Clostridium perfringens can cause a variety of foodborne illnesses.
Fortunately, most foodborne pathogens cannot survive modern sanitation measures. Even in case of extreme contamination, bacteria that remain after processing are unlikely to tolerate further cooking or heating.

Salmonella has occasionally been found in spices (such as pepper) and herbal teas. Though normally destroyed by thorough cooking, the Salmonella in spices can cause illness when the spices are added to food toward the end of the cooking process, when foods are improperly refrigerated or when leftovers are improperly stored for several days.

Molds and fungal growths
Left untreated, mold can produce aflatoxins, which destroy the flavour and colour of the ingredients and make them unsuitable for use.

The additional threat of pests
Pests such as beetles and lesser grain borers are also commonly found in spices, seeds, herbs and prepared seasonings. Fortunately, since infectious pests are more susceptible to decontamination measures than bacteria or molds, technology used to control microbial contamination will also kill pests.

Two effective solutions The world leader in microbial reduction services, Sterigenics offers the spice and food processing industries a choice of two sanitation options: ethylene oxide (EO) fumigation and irradiation processing.
While both effectively kill organisms, the challenges presented by the bulk packaging of spices and herbs have made ethylene oxide fumigation and gamma processing the methodologies of choice due to their efficient, highdensity penetration.
Often, the final destination of the spice and herb product plays a dominant role in the technology selection. Although EO fumigation is widely utilised in the US, it is not currently accepted in the
European Union.

EO fumigation: the original standard of excellence

Irradiation: today’s most effective and most preferred choice

A trusted means of spice sterilisation for more than 60 years, ethylene oxide fumigation uses alkylation as its mechanism of action.

Irradiation is achieved either by gamma rays, pure energy rays emitted from Cobalt-60 and similar in many ways to microwaves, or by accelerated electrons, commonly known as electron beam (E-beam) irradiation.
Approved by the FDA in 1988, gamma processing is the preferred method of food sterilisation in the US and on a global basis.

Usage of EO for food sanitation accelerated dramatically in the
1960s with the discovery that EO fumigation could significantly reduce spoilage organisms in spices and spice blends. From