Alternative preservatives

The lactoperoxidase enzyme is present in raw milk. This enzyme forms part of the lactoperoxidase system, which also includes thiocyanate and hydrogen peroxide produced by aerobic microorganisms in milk. The lactoperoxidase system produces an antimicrobial substance that exerts a preservative effect in raw milk (Blom and Mprtvedt, 1991). 

Many enzymes have been shown to have antimicrobial activity. These have been reviewed by Scott (1989) and Donnelly (1991). 

There are many plants that demonstrate antimicrobial activity. For reviews of the substances that are present in plants see Beuchat and Golden (1989), Janssen et al. (1987) and Aureli et al. (1992). 

(1992) Prevention by design the HACCP approach. Food Manufact. 67(4), 53, 54. Aureli, P., Constantini, A. and Zolea, S. (1992) Antimicrobial activity of some plant essential oils against Listeria monocytogenes. J. Food Protect. 55(5), 344-348. 

Axelsson, L.T., Chung, T.C., Dobrogosz, W.J. and Lindgren, S.E. (1989) Microb. Ecol. Health Disease 2, 131-136. 

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Included in the FDA Inactive Ingredients Guide (IM and ophthalmic preparations). Included in nonparenteral medicines licensed in the UK. In the UK, the use of phenylmercuric salts in cosmetics is limited to 0.003% (calculated as mercury, equivalent to approximately 0.0047% of phenylmercuric nitrate) as a preservative in shampoos and hair creams, which contain nonionic emulsifiers that would render other preservatives ineffective. Total permitted concentration, as mercury, when mixed with other mercury compounds is 0.007% (equivalent up to approximately 0.011% of phenylmercuric nitrate). Included in the Canadian List of Acceptable Non-medicinal Ingredients (ophthalmic, nasal and otic preparations only there must be no other suitable alternative preservative). 

In Table 12.1 a summary of complementary foodstuffs is presented. In a quest for alternative preservation methods and compounds, interest in the antimicrobial contents, and specifically the organic acid contents of such products, has increased. 

Table 12.1 Organic Acids Prevalent in Various Other Frequently Consumed Complementary Foodstuffs Considered as Potential Alternative Preservatives 266...

Recommendations regarding containers and preservation are published in Standard Methods and International Standards (ISO). For some analytes there may be a choice of method, for example alternative preservation methods may be applicable depending on whether it is practical to deliver samples to the analyzing laboratory within a few hours, or whether longer time periods cannot be avoided. 

The possible health risks of thimerosal (CH CH —Hg—S—C H —COOH), an antibacterial preservative used in vaccines, have been debated. The FDA has determined that that there is a significant safety margin incorporated into all the acceptable mercury exposure limits, and there are no data or evidence of any harm caused by the level of exposure that some children may have encountered in following the existing immunization schedule. Nevertheless, the availability of vaccines with alternate preservatives led to the removal of all vaccines containing thimerosal. 

In this chapter, the control of microorganisms will be discussed first, followed by alternative preservatives and alternative methods of preservation. 

It has been suggested that the manipulation of winemaking conditions to optimise the antimicrobial activity of SO2 may lead to a reduction in the amount of SO2 required in juice and wine, in addition to the use of alternative preservatives, used alone or in combination with a reduced amount of SO2. 

Chapter 6 on antimicrobial preservative-reduced foods by the editor, Jim Smith of the Prince Edward Island Food Technology Centre in Canada, addresses the control of microorganisms in foods and various strategies for producing preservative-reduced or preservative-free foods. This includes evaluating the processing environment, processing methods and the use of various alternative preservatives. 

Combined with the detrimental effects of 11F, the factors stated above formed the scientific reasoning behind development of an alternative preservation method preservation of cells in an undercooled state... 

Hexachlorophene <0.1% and when an alternative preservative has not been shown to be as effective and it may not be used in cosmetics to be applied to mucous membranes Neurotoxic effect and ability to penetrate human skin... 

Linked scan. A scan, in an instrument with two or more analyzers, in which two or more of the analyzer fields are scanned simultaneously to preserve a predetermined relationship between parameters that characterize these fields. Often these parameters are the field strengths, but they can be the frequencies in the case of analyzers that use alternating fields. 

In temperate climates extracts from some plants were found to be excellent preservatives for hides and skins. The hides, with or without hair, were placed in pits in the ground, then covered with alternating layers of bark or leaves and skins. Water was added and later, ie, days or months depending on the thickness of the hide, the hides could be removed, washed, and oiled. The resulting leather is flexible and lasts essentially forever. This procedure was used well into the seventeenth century as the most common method of tanning. In some isolated primitive societies, the method is used in the 1990s. 

Several methods have received considerable research attention as alternatives to salt curing. These include use of sodium bisulfite as a disinfectant to allow preservation with or without decreased salt in a brine cure use of disinfectants such as quatenary amines for temporary preservation in direct shipping to the taimery from the packing plant (see Disinfectants and antiseptics) preservation of hides by radiation sterilization (see Sterilization techniques) and substitution of materials such as potassium chloride for sodium chloride. These methods have found only limited commercial success. 

Starch is subject to fermentation by many microorganisms and, unless the mud is saturated with salt or the pH is >11.5, a preservative or biocide must be added if the mud is to be used for an extended period of time. The most common biocide until the mid-1980s was paraformaldehyde [9002-81-7]. This material has been largely replaced by isothia2olones (at 5—10 ppm cone) (74), carbamates, and glutaraldehyde [111-30-8]. Alternatively, the biocide may be incorporated during the processing of the starch and is present in the commercial product. 

Minor ingredients include excess fatty acids, preservatives, and potentially other synthetic surfactants. Alternatively, mixing can be achieved through the use of in-line static mixers, with the accurate addition of the minors into a flowing stream of the wet soap. 

Formulations. Any formulation is a compromise between the previously mentioned requirements. For example, the fermentation broth may contain enzyme-stabilizing substances, but the appHcation of the enzyme or precipitation problems in the formulation may demand a high degree of purification that eliminates the stabilizers. Alternatively, the pH necessary for good microbial or physical stabiHty may differ from the pH that gives optimum enzyme stabiHty, or a preservative that is effective at the optimum pH for enzyme stabiHty may have a denaturing effect on the enzyme. 

Both individual and societal risks may be presented on an absolute basis compared to a specific risk target or criterion. Or, they may be presented on a relative basis to avoid arguments regarding the adequacy of the absolute numbers while preserving the salient differences between alternatives. The end results of the risk presentation may be a single number (or a range of numbers if an uncertainty analysis was performed) or one or more graphs. 

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