502 ◾ Fundamental Food Microbiology
Conclusion
Many chemical compounds, approved by regulatory agencies, have been used to control growth
of pathogenic and spoilage microorganisms in food. In addition, some of them can kill microbial
cells and prevent germination of bacterial spores at concentrations used. Many of these compounds are more effective in combination with other methods. However, food environments can
greatly influence their effectiveness. They are, like the methods discussed before (except heat), not
used to eliminate pathogens from a contaminated food. However, irradiation (besides heat) is
used specifically to kill microbes present in food and is discussed in Chapter 39. In recent years,
herbs and spices are gaining considerable interest as food preservatives because they are considered
“green” natural antimicrobials. Bacteriophages are also a natural enemy of bacterial pathogens
and have received regulatory approval to control many foodborne pathogens not only for final
processed products but also to control pathogens in meat animals during preharvest.
QUESTIONS
1. Discuss the uses of antimicrobial chemicals before and after a.d. 1865, after 1958, and since
the 1980s.
2. Read the labels of 10 different foods from at least five food categories and identify in them
the chemicals having antimicrobial action (direct or indirect).
3. Define the terms bacteriostatic, germicidal, bactericidal, fungicidal, sporicidal, viricidal, and
sporostatic. Give one example of a preservative for each.
4. List five characteristics one should consider in selecting a suitable chemical preservative for
a specific food. What is a GRAS-listed preservative?
5. Discuss the antimicrobial properties and any health concern of the following chemical preservatives, and list two foods (for each) in which they are used: NO 2 , sulfites, bacteriocins,
parabens, benzoic acid, lysozyme, natamycin, and lactic acid.
6. Indicate the mechanism of antimicrobial actions of a bacteriocin, lysozyme, and EDTA.
From the information, indicate how, if used together, they can produce a synergistic antimicrobial effect.
7. Briefly discuss the life cycle of a lytic bacteriophage.
8. What are the advantages and disadvantages of using bacteriophage as food preservatives?
References
1. Davidson, P.M., Critzer, F.J., and Taylor, T.M., Naturally occurring antimicrobials for minimally processed foods, Annu. Rev. Food Sci. Technol., 4, 163–190, 2013.
2. Ray, B. and Daeschel, M.A., Biopreservatives of Microbial Origin, CRC Press, Boca Raton, FL, 1992.
3. Juneja, V.K., Dwivedi, H.P., and Yan, X., Novel natural food antimicrobials, Annu. Rev. Food Sci.
Technol., 3, 381–403, 2012.
4. Tiwari, B.K., Valdramidis, V.P., O’Donnell, C.P., Muthukumarappan, K., Bourke, P., and Cullen, P.J.,
Application of natural antimicrobials for food preservation, J. Agri. Food Chem., 57, 5987–6000, 2009.
5. Weiss, J., Gaysinsky, S., Davidson, M., and McClements, J., Nanostructured encapsulation systems:
Food antimicrobials, In Global Issues in Food Science and Technology, B.-C. Gustavo, M. Alan, L. David,
S. Walter, B. Ken, and Paul, C., Eds., Academic Press, San Diego, 2009, pp. 425–479.
6. Anonymous, Antimicrobial resistance: Implications for the food system. An expert report, funded by
the IFT Foundation, Comp. Rev. Food Sci. Food Safety, 5, 71–137, 2006.
Conclusion
Many chemical compounds, approved by regulatory agencies, have been used to control growth
of pathogenic and spoilage microorganisms in food. In addition, some of them can kill microbial
cells and prevent germination of bacterial spores at concentrations used. Many of these compounds are more effective in combination with other methods. However, food environments can
greatly influence their effectiveness. They are, like the methods discussed before (except heat), not
used to eliminate pathogens from a contaminated food. However, irradiation (besides heat) is
used specifically to kill microbes present in food and is discussed in Chapter 39. In recent years,
herbs and spices are gaining considerable interest as food preservatives because they are considered
“green” natural antimicrobials. Bacteriophages are also a natural enemy of bacterial pathogens
and have received regulatory approval to control many foodborne pathogens not only for final
processed products but also to control pathogens in meat animals during preharvest.
QUESTIONS
1. Discuss the uses of antimicrobial chemicals before and after a.d. 1865, after 1958, and since
the 1980s.
2. Read the labels of 10 different foods from at least five food categories and identify in them
the chemicals having antimicrobial action (direct or indirect).
3. Define the terms bacteriostatic, germicidal, bactericidal, fungicidal, sporicidal, viricidal, and
sporostatic. Give one example of a preservative for each.
4. List five characteristics one should consider in selecting a suitable chemical preservative for
a specific food. What is a GRAS-listed preservative?
5. Discuss the antimicrobial properties and any health concern of the following chemical preservatives, and list two foods (for each) in which they are used: NO 2 , sulfites, bacteriocins,
parabens, benzoic acid, lysozyme, natamycin, and lactic acid.
6. Indicate the mechanism of antimicrobial actions of a bacteriocin, lysozyme, and EDTA.
From the information, indicate how, if used together, they can produce a synergistic antimicrobial effect.
7. Briefly discuss the life cycle of a lytic bacteriophage.
8. What are the advantages and disadvantages of using bacteriophage as food preservatives?
References
1. Davidson, P.M., Critzer, F.J., and Taylor, T.M., Naturally occurring antimicrobials for minimally processed foods, Annu. Rev. Food Sci. Technol., 4, 163–190, 2013.
2. Ray, B. and Daeschel, M.A., Biopreservatives of Microbial Origin, CRC Press, Boca Raton, FL, 1992.
3. Juneja, V.K., Dwivedi, H.P., and Yan, X., Novel natural food antimicrobials, Annu. Rev. Food Sci.
Technol., 3, 381–403, 2012.
4. Tiwari, B.K., Valdramidis, V.P., O’Donnell, C.P., Muthukumarappan, K., Bourke, P., and Cullen, P.J.,
Application of natural antimicrobials for food preservation, J. Agri. Food Chem., 57, 5987–6000, 2009.
5. Weiss, J., Gaysinsky, S., Davidson, M., and McClements, J., Nanostructured encapsulation systems:
Food antimicrobials, In Global Issues in Food Science and Technology, B.-C. Gustavo, M. Alan, L. David,
S. Walter, B. Ken, and Paul, C., Eds., Academic Press, San Diego, 2009, pp. 425–479.
6. Anonymous, Antimicrobial resistance: Implications for the food system. An expert report, funded by
the IFT Foundation, Comp. Rev. Food Sci. Food Safety, 5, 71–137, 2006.