494 ◾ Fundamental Food Microbiology
Epoxides (Ethylene Oxide, Propylene Oxide)
Ethylene oxide and propylene oxide are used as fumigants to destroy microorganisms (and insects)
in grains, cocoa powder, gums, nuts, dried fruits, spices, and packaging materials. They are germicidal and effective against cells, spores, and viruses. Ethylene oxide is more effective. Epoxides
are alkylating agents and react with various groups (e.g., –SH, –NH 2 , and –OH) in cellular
macromolecules, particularly structural proteins and enzymes, adversely affecting their functions.
They can react with some food components, such as chlorides, and form toxic compounds that can
remain as residue in treated foods. They can be toxic at high concentrations (as residue), particularly to people who are sensitive to them.
Organic Acids
Acetic, propionic, lactic, citric, benzoic, and sorbic acids are used as food preservatives and are
discussed in Chapters 17 and 36. Organic acids are produced during microbial fermentation;
however, production of many of them at the industrial scale requires further optimization. 8
Parabens
Methyl and propyl esters of p-hydroxybenzoic acids are discussed in Chapter 36.
Diacetyl
Diacetyl is discussed in Chapter 17.
CO 2
CO 2 is discussed in Chapter 37.
Butylated Hydroxyanisol (BHA), Butylated Hydroxytoluene
(BHT), and t-Butyl Hydroquinone (TBHQ)
BHA, BHT, and TBHQ are primarily used at 200 ppm or less as antioxidants to delay oxidation
of unsaturated lipids. Additionally, they have antimicrobial properties and thus can be regarded as
indirect antimicrobials. In concentrations of 50–400 ppm, BHA inhibits growth of many grampositive and gram-negative bacteria; however, some species may be resistant to it. They also effectively prevent growth and toxin production by molds and growth of yeasts, but BHA seems to be
more effective. The antimicrobial action is most likely produced by their adverse effect on the cell
membrane and enzymes. Their antimicrobial effectiveness increases in the presence of sorbate but
decreases in foods with high lipids and at low temperature.
Monolaurin (Glycerol Monolaurate)
Monolaurin, the ester of lauric acid and glycerol, is one of the more effective bactericidal agents
among the different derivatives of lauric acid tested in foods. Its effectiveness in deboned meat,
chicken sausages, minced fish, and other foods has been observed against undesirable bacteria,
particularly the anaerobes. It also enhances the thermal inactivation of spores of Bacillus spp. The
Epoxides (Ethylene Oxide, Propylene Oxide)
Ethylene oxide and propylene oxide are used as fumigants to destroy microorganisms (and insects)
in grains, cocoa powder, gums, nuts, dried fruits, spices, and packaging materials. They are germicidal and effective against cells, spores, and viruses. Ethylene oxide is more effective. Epoxides
are alkylating agents and react with various groups (e.g., –SH, –NH 2 , and –OH) in cellular
macromolecules, particularly structural proteins and enzymes, adversely affecting their functions.
They can react with some food components, such as chlorides, and form toxic compounds that can
remain as residue in treated foods. They can be toxic at high concentrations (as residue), particularly to people who are sensitive to them.
Organic Acids
Acetic, propionic, lactic, citric, benzoic, and sorbic acids are used as food preservatives and are
discussed in Chapters 17 and 36. Organic acids are produced during microbial fermentation;
however, production of many of them at the industrial scale requires further optimization. 8
Parabens
Methyl and propyl esters of p-hydroxybenzoic acids are discussed in Chapter 36.
Diacetyl
Diacetyl is discussed in Chapter 17.
CO 2
CO 2 is discussed in Chapter 37.
Butylated Hydroxyanisol (BHA), Butylated Hydroxytoluene
(BHT), and t-Butyl Hydroquinone (TBHQ)
BHA, BHT, and TBHQ are primarily used at 200 ppm or less as antioxidants to delay oxidation
of unsaturated lipids. Additionally, they have antimicrobial properties and thus can be regarded as
indirect antimicrobials. In concentrations of 50–400 ppm, BHA inhibits growth of many grampositive and gram-negative bacteria; however, some species may be resistant to it. They also effectively prevent growth and toxin production by molds and growth of yeasts, but BHA seems to be
more effective. The antimicrobial action is most likely produced by their adverse effect on the cell
membrane and enzymes. Their antimicrobial effectiveness increases in the presence of sorbate but
decreases in foods with high lipids and at low temperature.
Monolaurin (Glycerol Monolaurate)
Monolaurin, the ester of lauric acid and glycerol, is one of the more effective bactericidal agents
among the different derivatives of lauric acid tested in foods. Its effectiveness in deboned meat,
chicken sausages, minced fish, and other foods has been observed against undesirable bacteria,
particularly the anaerobes. It also enhances the thermal inactivation of spores of Bacillus spp. The