Fermentation technology: safety in a bioreactor.

Fermented foods and ingredients generally have an enviable record of safety. With the exception of isolated incidents of foodborne disease in some fermented dairy and meat products, the biochemical nature of fermented foods often renders them free of safety hazards.

There are three main hazards associated with bioreactor processing technology. These are biological, chemical and physical hazards. Biological hazards--pathogenic microbes and microbial toxins--may enter bioreactors either through contaminated raw materials or through the poor personal hygiene of workers. Bioreactors equipped with open aerators can aerosol microbe-entrained mists. Inhaling pathogenic microbes may cause allergic reactions or illness among workers, while their ingestion by consumers may result in morbidity and mortality.

Chemical hazards, such as some nutrients, methanol, acids and bases, can cause irritation of the eyes, skin, and respiratory tracts of workers. Likewise, fermentation byproducts, such as carbon dioxide, may be toxic to workers in confined spaces. Toxic chemicals--heavy metals, pesticides, industrial wastes and radionuclides--in raw materials can sometimes be present in final products.

Physical hazards, including the storage and use of alcohols or other flammable- explosive substances, are a cause for concern, especially when pure oxygen is used as a reactant. Improperly grounded electrical connects can be an electrocution hazard. The presence of hard or sharp foreign objects can injure consumers.

Controlling these hazards can be achieved by properly implementing current good manufacturing practices and the application of hazard analysis critical control point (HACCP) plans. Bioreactor design, construction, operation and maintenance are appropriate control points from which to manage bioreactor safety. Paying careful attention to the quality of raw materials, proper strain selection and adequate process control gives processors the ability to safely manufacture fermented foods, beverages and ingredients. Current safety challenges include purifying ingredients to remove residual contaminants, such as toxins, microorganisms, nucleic acids and host cell proteins.

Further information. Douglas Marshall, Department of Food Science, Nutrition and Health Promotion, Mississippi State University, 110 Herzer Building, Mailstop 9805, Mississippi State, MS 39762; phone: [phone]; fax: [phone]; email: [e-mail].