Phosphates

Some phosphate compounds, including sodium acid pyrophosphate (SAPP), tetrasodium pyrophosphate (TSPP), sodium tripolyphosphate (STPP), sodium tetrapolyphosphate, sodium hexametaphosphate (SHMP), and triso-dium phosphate (TSP), have variable levels of antimicrobial activity in foods (45). Gram-positive bacteria are generally more susceptible to phosphates than Gramnegative bacteria. TSPP, SAPP, STPP, and SHMP have been shown to inhibit Bacillus subtilis, Enterococcus faecalis, Clostridium sporogenes, C. bifermentans, and Staphylococcus aureus (45,46). Sodium polyphosphates at 1% inhibited lag and generation times of Listeria monocytogenes in BHI broth, especially in the presence of NaCl (47). Wagner and Busta (48) found that SAPP has no effect on the growth of C. botulinum but delayed or prevented toxicity to mice. It was theorized that this was due to binding of the toxin molecule or inactivation of the protease responsible for protoxin activation.

Phosphate derivatives also have antimicrobial activity in food products (49). SAPP, SHMP, or polyphosphates enhance the effect of nitrite, pH, and salt against C. botulinum (45). Phosphates, sodium chloride, reduced water activity, water content, reduced pH, and lactic acid interact to prevent the outgrowth of C. botulinum in pasteurized process cheese (50). A 10% sodium tetrapolyphosphate dip preserved cherries against the fungal growth by Penicillium, Rhizopus, and Botrytis (45). Various phosphate salts have antimicrobial activity against rope-forming Bacillus in bread and Salmonella in pasteurized egg whites (51). Trisodium phosphate (TSP) at levels of 8 to 12% reduces pathogens, especially Salmonella, on poultry most likely due to a physical removal process or high pH (11-12) (52,53).

Several mechanisms have been suggested for bacterial inhibition by polyphosphates. The ability of polyphosphates to chelate metal ions, such as magnesium, appears to play an important role in their antimicrobial activity (45). Knabel et al. (54) stated that the chelating ability of polyphosphates is responsible for growth inhibition of B. cereus, L. monocytogenes, S. aureus, Lactobacillus, andAs-pergillus flavus. In addition, inhibition is reduced at lower pH due to protonation of the chelating sites on the polyphosphates. It was concluded that polyphosphates inhibited Gram-positive bacteria and fungi by removal of essential cations from binding sites on the cell walls of these microorganisms (54).

5 Common Skin Problems Answered

5 Common Skin Problems Answered

Our skin may just feel like a mere shield that protects us from the world outside. But, the fact is, its more than just the mask that keeps your insides in. It is a very unique and remarkable complex organ that reflects our general health.

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