Preservative agents

Both sorbic acid and potassium sorbate may be used under U.S. Department of Treasury, Bureau of Alcohol, Tobacco, and Firearms regulations as sterilizing and preservative agents for treatment of wine and juice at up to 300 ppm/L (158). 

Sodium or potassium benzoate at a concentration of 0.05% is a universally used preservative agent active against yeast and mold. At higher concentrations benzoate is also effective against bacteria. It is most effective at a pH between 2.0 and 4.0. Sodium or potassium sorbate inhibits the growth of yeast and mold and is most effective below pH 6.5. 

Curcumin (diferuloyl methane) is the main pigment of turmeric. It is widely used as a colorant and preservative agent. No data regarding its daily intake in western countries are available intake may reach 80 to 200 mg in adult Indians. To date, no study has explored the effect of curcumin consumption on the incidence of diseases, but many beneficial effects on health have been reported in cell and animal models. These include anti-carcinogenic, anti-diabetic, anti-atherosclerotic, and anti-Alzheimer s disease properties. ... 

Stability of surfactants in a water matrix, even using different preservation agents, is poor and serious, quantitative and qualitative changes in sample integrity occur if the storage exceeds 7 days. The most suitable preservation additive is formaldehyde (minimum 3%) for non-ionic surfactants and LAS, and acidification to pH < 3 for benzene and naphthalene sulphonates. However, storage for longer than 7 days is not recommended. 

The preservative must be completely compatible with all other formulative ingredients and does not interfere with them, nor do they interfere with the effectiveness of the preservative agent. 

Preservative agents are added to injectable preparations when multiple dosing is expected out of the same unit. Examples of preservatives used in injectable preparations include phenol, benzyl alcohol, methyl and ethyl parabens, and benzalkonium... 

Pure, sound milk should have the normal colour, taste and smell it should contain no extraneous substances, antiseptics or other preservative agents and should contain no pathogenic micro-organisms, which are detectable by bacteriological examination and by the behaviour towards the reductase test (see 10. ). 

Pasteurised or sterilised milk is recognised by the tests already given (p. 29) it has the same composition as natural milk, and should not contain antiseptics or other preservative agents. 

Shelf stability of a product is of critical importance because it is affected by longterm antimicrobial and antioxidizing activity enhanced by preservative agents compared to only antimicrobial agents that are added to dressings for thwarting infection in a wound. Preferably, a preservative can be added to a product that possesses broad-spectrum antimicrobial activity that will allow the product to maintain activity before reaching a planned expiration date, and prevent infection when applied to wounds. 

Commonly used preservative agents include organic acids such as benzoic acid and salts, the parabens, (alkyl esters ofp-hydroxybenzoic acid), sorbic acid and salts, phenolic compounds, quaternary ammonium compounds, alcohols, and mercurials such as thimerosal in 0.001-0.004% concentration. 

The material was prepared by freeze drying pooled, urine samples obtained from healthy volunteers. Sodium merthiolate was used as preservative agent. 

The very first NS with LMC (design 645) was equipped with two-reactor Power Reactor Installation (PRI). After the port-side-reactor accident during the second fuel lifetime (1968), the NS was kept afloat for some period. Then, after filling of free reactor cavities and the whole Reactor Compartment (RC) with preservative agents, the NS was dumped in the Kara Sea close to the Novaya Zemlia (New Land) archipelago at 50-m depth (1981). Some characteristics of NS, design 645, are given in Table 2. 

The NS 900 put into operation in 1970 was the very first vessel of designs 705 and 705K. In 1972 because of failure of NS primary circuit s auxiliary pipelines and impossibility of their repair, the NS was taken out of service after expiration of only 10% of fuel lifetime in the reactor. The RC was cut out of NS, and free cavities of the primary circuit were filled with preservative agents on furfurol basis. A bitumen-layer of about 1000 mm was laid over the whole surface of the upper deck of RC including the reactor upper head. Under such condition the RC is to be stored with nuclear fuel for long within the waterborne storage center. Some characteristics of NS, design 705, are demonstrated in Tables 3, 4 and 5. 

Salt Salt has been a known preservation agent for centuries. Its use in dressings complements vinegar and other preservatives in producing shelf-stable dressing products. Salt also serves as an important source of zesty flavor as well as a flavor enhancer for a number of other ingredients. 

Table 5 Antimicrobial preservative agents in small-volume parenterals...

Fig. 3 Comparisons of the activity and concentration exponents of four hypothetical preservatives. Agents A B and C D have similar concentration exponents but different activities, whereas A C and B D have similar activities yet different concentration exponents.

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