Food Biopreservatives of Microbial Origin, Bacteriocin, and Nanotechnology ◾ 229
they can be used as food biopreservatives. Although some are currently used in a limited way,
approval by regulatory agencies will be necessary for the use of others in food.
QUESTIONS
1. List the antimicrobial compounds produced by different starter-culture bacteria.
2. Discuss the mode of antibacterial action of organic acids produced by starter-culture bacteria. At pH 6.0, why are propionic and acetic acids more antibacterial than lactic acid? List
the advantages of using these acids in food preservation.
3. Describe the mode of antibacterial action of diacetyl and discuss why it has limited use as a
food biopreservative.
4. Under what conditions can some lactic acid bacteria generate sufficient quantities of H 2 O 2 to
inhibit other microorganisms in a food system? What are some disadvantages of using H 2 O 2
in food?
5. Discuss the advantages of using small amounts of H 2 O 2 in raw milk to inhibit psychrotrophic bacteria, such as Pseudomonas species. What needs to be done before pasteurizing this
milk?
6. Define bacteriocins of lactic acid bacteria and list their four general characteristics.
7. How are bacteriocins grouped? Give one example of each group.
8. Define the terms prepeptide, propeptide, leader peptide, thioether rings, disulfide bonds,
and thiol group in relation to the structure of bacteriocins.
9. List two important similarities in the amino acid sequence of cystibiotics that are related to
their bactericidal property.
10. List three features of plasmid-encoded bacteriocins of lactic acid bacteria.
11. Briefly list differences in gene organizations associated with bacteriocin production in lactic
acid bacteria.
12. Using either pediocin AcH or nisin A as an example, briefly explain the function of genes in
the production of active molecules.
13. Briefly discuss how bacteriocin production of a producer strain of lactic acid bacteria can be
enhanced.
14. List five potential applications of bacteriocins of lactic acid bacteria as food preservatives.
15. Briefly explain (a) potential therapeutic uses of bacteriocins and (b) use of antimicrobial
properties of yeasts to preserve foods.
16. What strategies are used to improve functionality of bacteriocins? Use examples.
17. Define nanoencapsulation technology. What are the advantages of using nanoencapsulation
for bacteriocin delivery?
References
1. Ray, B., Cells of lactic acid bacteria as food biopreservatives. In Food Biopreservatives of Microbial Origin,
Ray, B. and Daeschel, M.A., Eds., CRC Press, Boca Raton, FL, 1992, p. 81.
2. Pawlowska, A.M., Zannini, E., Coffey, A., and Arendt, E.K., “Green preservatives”: Combating fungi
in the food and feed industry by applying antifungal lactic acid bacteria, Adv. Food Nutr. Res., 66,
217–238, 2012.
3. Ray, B. and Sandine, W.E., Acetic, propionic and lactic acids of starter culture bacteria as biopreservatives. In Food Biopreservatives of Microbial Origin, Ray, B. and Daeschel, M.A., Eds., CRC Press, Boca
Raton, FL, 1992, p. 103.
they can be used as food biopreservatives. Although some are currently used in a limited way,
approval by regulatory agencies will be necessary for the use of others in food.
QUESTIONS
1. List the antimicrobial compounds produced by different starter-culture bacteria.
2. Discuss the mode of antibacterial action of organic acids produced by starter-culture bacteria. At pH 6.0, why are propionic and acetic acids more antibacterial than lactic acid? List
the advantages of using these acids in food preservation.
3. Describe the mode of antibacterial action of diacetyl and discuss why it has limited use as a
food biopreservative.
4. Under what conditions can some lactic acid bacteria generate sufficient quantities of H 2 O 2 to
inhibit other microorganisms in a food system? What are some disadvantages of using H 2 O 2
in food?
5. Discuss the advantages of using small amounts of H 2 O 2 in raw milk to inhibit psychrotrophic bacteria, such as Pseudomonas species. What needs to be done before pasteurizing this
milk?
6. Define bacteriocins of lactic acid bacteria and list their four general characteristics.
7. How are bacteriocins grouped? Give one example of each group.
8. Define the terms prepeptide, propeptide, leader peptide, thioether rings, disulfide bonds,
and thiol group in relation to the structure of bacteriocins.
9. List two important similarities in the amino acid sequence of cystibiotics that are related to
their bactericidal property.
10. List three features of plasmid-encoded bacteriocins of lactic acid bacteria.
11. Briefly list differences in gene organizations associated with bacteriocin production in lactic
acid bacteria.
12. Using either pediocin AcH or nisin A as an example, briefly explain the function of genes in
the production of active molecules.
13. Briefly discuss how bacteriocin production of a producer strain of lactic acid bacteria can be
enhanced.
14. List five potential applications of bacteriocins of lactic acid bacteria as food preservatives.
15. Briefly explain (a) potential therapeutic uses of bacteriocins and (b) use of antimicrobial
properties of yeasts to preserve foods.
16. What strategies are used to improve functionality of bacteriocins? Use examples.
17. Define nanoencapsulation technology. What are the advantages of using nanoencapsulation
for bacteriocin delivery?
References
1. Ray, B., Cells of lactic acid bacteria as food biopreservatives. In Food Biopreservatives of Microbial Origin,
Ray, B. and Daeschel, M.A., Eds., CRC Press, Boca Raton, FL, 1992, p. 81.
2. Pawlowska, A.M., Zannini, E., Coffey, A., and Arendt, E.K., “Green preservatives”: Combating fungi
in the food and feed industry by applying antifungal lactic acid bacteria, Adv. Food Nutr. Res., 66,
217–238, 2012.
3. Ray, B. and Sandine, W.E., Acetic, propionic and lactic acids of starter culture bacteria as biopreservatives. In Food Biopreservatives of Microbial Origin, Ray, B. and Daeschel, M.A., Eds., CRC Press, Boca
Raton, FL, 1992, p. 103.