By Dr. Hassan Gourama, Associate Professor of Food Science
In every society, ensuring that the food supply is safe is essential. However, despite many scientific and technological advances in the area of food production, processing, and preservation, foodborne illnesses around the world, including in the United States, still occur.
Just in the United States alone, the Centers for Disease Control estimates that every year, 48 million people (one in six Americans) get sick, 128,000 are hospitalized, and 3,000 die of foodborne illnesses. The financial cost is estimated to reach billions of dollars due to hospitalizations, loss of productivity, and other economic losses.
The groups of microorganisms that can cause theses foodborne illness are predominantly bacterial pathogens such as Salmonella, pathogenic E. coli, and Campylobacter, but also include toxigenic fungi and some viruses such as Norwalk-like viruses.
For the last three decades, my research has focused on the identification, detection, and control of spoilage and pathogenic microorganisms in foods and drinking water. Although I work with all foodborne organisms, my major research focus is food mycology and mycotoxicology–the study of foodborne fungi and their toxins.
Filamentous fungi, what we refer to as molds, are found in a wide range of foods, crops, and environments. The ubiquitous presence of fungi is due to their versatile nutritional and environmental requirements. They have the capacity to use many types of substrates and they can tolerate conditions such as low pH, low temperature, and low water activity.
The beneficial effects of certain molds have been known for years. Molds have not only served to synthesize antibiotics, but also to produce some foods. Fermented foods, such as some cheeses, soy sauce, miso, tempeh, and other delicacies are all prepared with the help of molds in combination with lactic acid bacteria and/or yeasts.
However, molds are also major spoilage agents of foods and crops. It is difficult to accurately determine the economic cost due to fungal spoilage, but it is safe to say that it is high. In addition to economic losses, molds growing on foods and crops present a potential health hazard to humans and animals by producing toxic substances known as mycotoxins. Toxigenic molds have caused food safety problems for as long as foods have been harvested and stored.
However, the intensive study of toxigenic fungi and fungal toxins has only taken place since 1960, when it led to the discovery of aflatoxins, one of the most significant groups of mycotoxins. The discovery of aflatoxins led to the realization that mold metabolites could cause disease and death in animals and humans, and stimulated intensive and extensive research on toxigenic molds and mycotoxins. Since the discovery of aflatoxins, numerous mold species have been tested in the laboratory for the production of mycotoxins.
The molds that produce the mycotoxins of most concern are found in five mold genera: Aspergillus, Penicillium, Fusarium, Alternaria, and Claviceps. The mycotoxins currently receiving the most attention by researchers and regulators as potential hazards to humans and animal health include aflatoxins, ochratoxins, patulin, zearalenone, fumonisins, and trichothecens. These fungal metabolites have been shown to be carcinogenic, mutagenic, and teratogenic, causing symptoms that range from skin irritation, to immunosuppression, to birth defects, neurotoxicity, and death.
My primary research has focused on the control of aflatoxins in foods and cereal crops. I am interested in the use of biological control measures to control the growth of these toxigenic fungi and the production of mycotoxins in the food supply. In addition, the increasing concerns about the safety of chemical preservatives justify the development of alternative preservation techniques.
One of the alternatives I focus on is the exploration of the antifungal properties of lactic acid bacteria and probiotic bacteria used in the fermentation of dairy and other food products. My research has shown that some of these natural beneficial bacteria have the potential to inhibit the growth of fungi and the production of mycotoxins such as aflatoxins. Here at Penn State Berks, we are researching the antimicrobial and antitoxigenic properties of these beneficial bacteria.
Another research project that I started at the Berks campus is the comparison of the fungal flora and their toxins of foods that are labeled organic to those that are conventionally produced. In the literature, there have been only a few studies that have compared the differences between organic and conventional foods with respect to their microbiological and toxicological safety.
Other research projects that I have been involved with include the study of the virulence characteristics of fungi and bacteria isolated from bottled water, and the use of the FTIR spectroscopy for the identification and characterization of foodborne fungi. Some of these projects have been conducted in collaboration with colleagues in the Biology and Chemistry departments here at Penn State Berks.
I also enjoy working with undergraduate students on research projects. Every year I supervise undergraduates on their research projects. A number of these students were able to present their work at national microbiology or food science conferences and publish their work, and some were accepted into graduate programs to pursue their M.S. and Ph.D. degrees or to attend medical schools.
My research also helped enhance my teaching and outreach activities. Every year I offer a senior-level course on “Fungi and Mycotoxins” to students in the Biology and the Life Science majors. I also codirect, in collaboration with a colleague at University Park, the Penn State Food Microbiology and Food Mycology short courses. These courses are designed for technical professionals working in the industry.
In addition to working with colleagues and students here at the Berks campus, I also collaborate with faculty and graduate students in the Department of Food Science at the University Park campus. These research projects have included: Microbial Survey of Pennsylvania Surface Water Used for Specialty Crop Irrigation and Development of Sampling and Handling Procedures for Surface Water Testing; Developing New Technologies and Programs to Enhance the Safety and Security of Dairy Products; Multiple Strategies for Control of Patulin in Apples and Apple Products; and Multiple Hurdle Strategies to Control Pathogens in Fresh and Mold Ripened Soft Cheeses. These projects have been supported by USDA grants.