Understanding Food Science Disciplines - What is Food Microbiology?
Microbiology is the science of microscopic organisms including bacteria, fungi, and algae, as well as viruses, which are parasitic elements that need to infect living cells in order to multiply. Microorganisms are important to virtually all processes on Earth and are ubiquitous in natural and human-built environments. Microbiology has several sub-disciplines and touches several other areas of science.
The field engages with many of the problems of modern society including energy security, public health and ensuring food safety and quality. There is a branch of science called food microbiology that studies the microbial ecology of foods. Food microbiologists apply the learnings from this research to preserve food and control the growth of pathogenic and spoilage microorganisms to ensure healthy and shelf-stable foods (Hungaro et al., 2014). They also use their knowledge to optimize food production processes built on the activity of microorganisms such as production of wine, beer, yogurt, cheese, sauerkraut and many other fermented products.
How do Microorganisms Play a Role in Food Production?
Microorganisms can be beneficial or detrimental to food production and safety. Here are a few groups of common microorganisms that play a part in food production.
Bacteria
Pathogenic Bacteria
Several bacteria can be a serious challenge for the food industry because of their ability to cause foodborne illnesses. Common pathogenic bacteria include Salmonella, shigatoxigenic Escherichia coli, and Listeria monocytogenes. In addition spore-forming bacteria, such as Clostridium botulinum and Bacillus cereus are of great concern because the spores produced can survive extreme processing conditions and later germinate and grow to form toxins in the food.
Probiotics
Probiotics, on the other hand, are used for their beneficial properties. By definition, probiotics are “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host” (FAO / WHO, 2001, 2006). It follows that probiotic food products and dietary supplements must contain adequate amounts to achieve the promised health benefit, even at the end of their shelf life. Current US labeling regulations require probiotic content to presented as total weight on the product label, but also permit cfu/g or cfu/serving to be labeled alongside the weight. As such, the matrix, choice of production technology, consistency of the raw materials, packaging properties and distribution conditions are some of the factors you should consider to ensure that probiotic products maintain their probiotic content from production to the market shelves to the consumers (Neffe-Skocinska et al., 2018).
Lactic Acid Bacteria (LAB)
Lactic acid bacteria play a positive role in the production of many fermented products. They consume carbohydrates naturally present in the unfermented food to produce lactic acid and other metabolites that provide the unique properties of fermented products. Lactic acid bacteria are central to production of yogurt, kefir, many cheeses, sauerkraut and many other pickles and even meat products such as salami and chorizo.
Lactic acid bacteria also can play a negative role in food quality. Certain LAB are found in spoiled products and can produce products affecting flavor, odor, and color in a product.
Indicator Organisms
Indicator organisms tell us something about the microbiological condition of a food or environment without looking directly for the presence of pathogens. Classical sanitation indicators include coliform organisms, total Enterobacteriaceae and enterococci, all of which can suggest fecal contamination or general lack of sanitary conditions.
Other types of microorganisms that tell us something about the overall microbiological condition of a food include total aerobic or anaerobic bacteria. Mesophilic or thermophilic spore-formers can indicate spoilage potential in heat-processed foods. Acid tolerant and cold tolerant bacteria can indicate spoilage potential of acidic or refrigerated foods, respectively. Selection of appropriate indicator organisms should be made in the context of the unique formulation and processing conditions of each individual product.
Yeasts and Molds
Using fungi to produce beer, wine, bread, and soy sauce has been reported for centuries. In the industrial world, the fermentation process has boundless possibilities with a variety of food products and processes created by these microorganisms.
Traditionally, one-celled fungi such as yeast have been used for production of alcoholic beverages and leavened breads. One species of yeast, Saccharomyces cerevisiae is the most used species in food production. Aside from producing alcoholic beverages, S. cerevisiae is also used as a leavening agent in baking, resulting in the spongy-like texture of bread and pastries (Lorenzo et al., 2018). Additionally, S. cerevisiae subspecies boulardii is a well-known probiotic yeast.
Molds are multicellular and filamentous fungi. As such, their growth in food can be quite conspicuous due to their mycelium formation, recognized by their fuzzy or cottony appearance. With the right oxygen availability, pH, temperature, and water concentration, molds can cause spoilage in food.
Examples of spoilage molds include Aspergillus, which grows well in foods with high sugar and salt concentration and low moisture, and Rhizopus, which causes spoilage in vegetables, berries, and bread.
However, not all molds cause negative effects on food as some are used for food manufacturing. Mucor is a genus of molds used to produce enzymes used in a variety of food processes. Some Penicillium species are used for the ripening of some cheeses and fermented sausages (Lorenzo et. al., 2018).
Viruses
Viruses are organisms that cause diseases in animals, humans, and even plants. There are relatively few pathogenic foodborne viruses, but they strongly impact the produce and food service industry. Hepatitis A and Norovirus are two of the most commonly recognized human foodborne pathogens. These viruses are highly infectious and caused several outbreaks in the past years (Lorenzo et al., 2018). It is important to note that viruses cannot “grow” or reproduce themselves without infecting a susceptible host cell, so presence of pathogenic viruses on a food results from external contamination at some stage of production or distribution.
What Factors Affect Microbial Growth in Food?
Several environmental factors affect microbial growth in foods. The most important are:
- Temperature
- Water Activity (at higher water activity, moisture is more “available” to support microbial growth)
- pH (values below 7.0 are acidic, values above 7.0 are alkaline)
- Oxygen concentration
As such, certain measures are taken by food manufacturers to control the growth of microorganisms in food, for example:
- Storing in low temperatures,
- Drying, salting and sugaring (to lower water activity),
- Adding acids, and fermentation (to lower the pH),
- Packaging in modified atmospheres to reduce oxygen concentration.
Shelf life extension and food safety can also be improved with processes including pasteurization, aseptic processing, irradiation, and other technology. It is important to comprehensively evaluate your products to determine microbiological risks and what you can do to maintain or improve their safety and quality in the market.
Understanding Microorganisms in Food Production
Microbiology is an important aspect of food production, safety, and quality. Ensure that you're producing, manufacturing, selling, or distributing the best quality food products. If you have questions or need guidance, contact our lab with any needs.
