Control by Physical Removal ◾ 447
Food Safety Authority (EFSA) has established guidelines toward carcass decontamination that
include application of (a) a physical method, such as hot water, steam, and steam vacuuming; (b) a
chemical method, such as organic acids, chlorine, acidified sodium chlorite, polyphosphates; and
(c) biological methods, such as bacteriophages and bacteriocins. 9 Combined physical and chemical
treatments are also proposed and have proven to be more effective than a single treatment scheme.
The suitability of the combinations as well as their concentration and duration of application
must be determined. One has to recognize that, with time, microorganisms can form a biofilm on
the carcass surface (Chapter 7). The nature of the biofilm varies with microbial species and strains.
Also, with time, the biofilm becomes more stable, and removing microorganisms by washing after
the formation of a stable biofilm is relatively difficult. This aspect needs to be considered while
developing effective methods of carcass washing. Removal of pathogens from carcass surfaces will
be an important area to develop a suitable intervention strategy for ensuring the safety of meat and
meat products (see Appendix C).
Conclusion
Microorganisms that have gained access to food can be controlled by various means, one of which
is to remove them physically. This can be achieved by the different methods discussed in this chapter. Some of them are used in liquid foods but have limited applications; others are used in solid
foods. Chapter 33 discusses different methods of heating to kill microorganisms already present
in food.
QUESTIONS
1. List the methods used to remove microorganisms from foods and discuss one advantage and
one disadvantage of each method.
2. Discuss two specific microbiological disadvantages, with examples, of trimming food for
visible microbial growth or microbial contamination.
3. Discuss two specific microbiological disadvantages, with examples, of washing carcasses of
animals and birds to reduce microorganisms.
4. List six different agents that have been tested and discuss their relative efficiency in removing
microorganisms from beef carcasses.
5. A milk processor found that a batch of milk had very high levels of bacterial spores that
could increase the SPC level following pasteurization. Discuss a physical removal procedure
that he could use to remove the spores to attain the desired SPC level.
References
1. Bennett, A., Drinking water: Pathogen removal from water—technologies and techniques, Filtration
and Separation, 45, 14–16, 2008.
2. Koeseoglu, S.S., Lawhon, J.T., and Lusas, E.W., Use of membranes in citrus juice processing, Food
Technol., 44, 90–97, 1990.
3. Corry, J.E.L., James, S.J., Purnell, G., Barbedo-Pinto, C.S., Chochois, Y., Howell, M., and James, C.,
Surface pasteurisation of chicken carcasses using hot water, J. Food Eng., 79, 913–919, 2007.
4. Gill, C.O., Effects on the microbiological condition of product of decontaminating treatments routinely applied to carcasses at beef packing plants, J. Food Prot., 72, 1790–1801, 2009.
Food Safety Authority (EFSA) has established guidelines toward carcass decontamination that
include application of (a) a physical method, such as hot water, steam, and steam vacuuming; (b) a
chemical method, such as organic acids, chlorine, acidified sodium chlorite, polyphosphates; and
(c) biological methods, such as bacteriophages and bacteriocins. 9 Combined physical and chemical
treatments are also proposed and have proven to be more effective than a single treatment scheme.
The suitability of the combinations as well as their concentration and duration of application
must be determined. One has to recognize that, with time, microorganisms can form a biofilm on
the carcass surface (Chapter 7). The nature of the biofilm varies with microbial species and strains.
Also, with time, the biofilm becomes more stable, and removing microorganisms by washing after
the formation of a stable biofilm is relatively difficult. This aspect needs to be considered while
developing effective methods of carcass washing. Removal of pathogens from carcass surfaces will
be an important area to develop a suitable intervention strategy for ensuring the safety of meat and
meat products (see Appendix C).
Conclusion
Microorganisms that have gained access to food can be controlled by various means, one of which
is to remove them physically. This can be achieved by the different methods discussed in this chapter. Some of them are used in liquid foods but have limited applications; others are used in solid
foods. Chapter 33 discusses different methods of heating to kill microorganisms already present
in food.
QUESTIONS
1. List the methods used to remove microorganisms from foods and discuss one advantage and
one disadvantage of each method.
2. Discuss two specific microbiological disadvantages, with examples, of trimming food for
visible microbial growth or microbial contamination.
3. Discuss two specific microbiological disadvantages, with examples, of washing carcasses of
animals and birds to reduce microorganisms.
4. List six different agents that have been tested and discuss their relative efficiency in removing
microorganisms from beef carcasses.
5. A milk processor found that a batch of milk had very high levels of bacterial spores that
could increase the SPC level following pasteurization. Discuss a physical removal procedure
that he could use to remove the spores to attain the desired SPC level.
References
1. Bennett, A., Drinking water: Pathogen removal from water—technologies and techniques, Filtration
and Separation, 45, 14–16, 2008.
2. Koeseoglu, S.S., Lawhon, J.T., and Lusas, E.W., Use of membranes in citrus juice processing, Food
Technol., 44, 90–97, 1990.
3. Corry, J.E.L., James, S.J., Purnell, G., Barbedo-Pinto, C.S., Chochois, Y., Howell, M., and James, C.,
Surface pasteurisation of chicken carcasses using hot water, J. Food Eng., 79, 913–919, 2007.
4. Gill, C.O., Effects on the microbiological condition of product of decontaminating treatments routinely applied to carcasses at beef packing plants, J. Food Prot., 72, 1790–1801, 2009.