Organic acids antimicrobial

With its wealth of information and rare focus solely on the subject, this book provides practical tools to help readers better understand these and other problems and then develop optimal solutions and strategies. It discusses mechanisms of organic acid antimicrobial action and facilitates troubleshooting techniques regarding problems with preservatives and microorganisms. It also shows how to predict the effectiveness of a preservation method or application. 

Organic acids may inhibit growth when present in the undissociated form because of their abiHty to change the pH inside the ceU. The most efficient are benzoic acid and sorbic acid, but formic, acetic, and propionic acid also have this effect. The parabens, ie, -hydroxy benzoic acid esters, are also used because of their antimicrobial effect over a broad pH range. 

D. Oppong and C. G. Hollis. Synergistic antimicrobial compositions containing (thiocyanomethylthio)benzothiazole and an organic acid. Patent WO 9508267, 1995. 

The pH of the finished product may have a strong influence on the type of preservative used. A good example of this can be seen with the use of organic acids which may exist in a predominantly dissociated or an undissociated form as a consequence of the product pH. The undissociated form is considered to confer the antimicrobial activity and the effect of pH on benzoic, sorbic and dehydroacetic acid is described in the graph below. It can be seen that, at the normal pH of most personal care products ie. 5.5 to 7.0, there is little activity remaining. Hence organic acids would be suitable preservatives for predominantly acidic products, such as astringent washes made with lemons. 

For HPLC analysis of preservatives (antimicrobials such as polar organic acids, or antioxidants such as... 

Different organic acids, primarily lactic acid, have been successfully used for decontamination of whole livestock carcasses, and the application of different organic acids used for decontamination has also been tested in the fruit and vegetable industry. Organic acids other than lactic acid that are known to have bactericidal effects are acetic, benzoic, citric, malic, propanoic, sorbic, succinic and tartaric acids (Betts and Everis 2005). The antimicrobial action is due to a reduction in the pH in the bacterial environment, disruption of membrane transport, anion accumulation or a reduction in the internal pH in the cell (Busta et al., 2001). Many fruits contain naturally occurring organic acids. Nevertheless, some strains, for example E. coli 0157, are adapted to an acidic environment. Its survival, in combination with its low infective dose, makes it a health hazard for humans. 

According to the food laws and regulations of the Food and Drug Administration (FDA), organic acids can be used as acidulants (e.g., citric, fumaric, malic, and sorbic acid), antimicrobial additives (e.g., propionic acid), and sequestrants (e.g., tartaric acid) (14). Most fatty acids of... 

Antimicrobial activity, within a pharmaceutical context, is generally found only in the organic acids. These are weak acids and will therefore dissociate incompletely to give the three entities HA, H+ and A- in solution. As the undissociated form, HA, is the active antimicrobial agent, the ionization constant, Ka, is important and the pKa of the acid must be considered, especially in formulation of the agent. 

The unbound drug in the systemic circulation is available to distribute extravascularly. The extent of distribution is mainly determined by lipid solubility and, for weak organic acids and bases, is influenced by the pK3/pH-dependent degree of ionization because only the more lipid-soluble non-ionized form can passively diffuse through cell membranes and penetrate cellular barriers such as those which separate blood from transcellular fluids (cerebrospinal and synovial fluids and aqueous humour). The milk-to-plasma equilibrium concentration ratio of an antimicrobial agent provides a reasonably... 

LAB produce a wide variety of antimicrobial compounds such as bacterio-cins, organic acids, hydrogen peroxide, and other low-molecular-weight metabolites (discussed previously). Production of these substances may be the primary mechanism for reduction of the food-borne pathogens in vivo. 

Ricke, S.C. 2003. Perspectives on the use of organic acids and short chain fatty acids as antimicrobials. Poultry Science 82 632-639. 

The natural occurrence of varying amounts of organic acids in honeys from different geographical areas have been documented. Much research is being done to determine the use of honey as an antimicrobial agent in various food systems (Suarez-Luque et al., 2002). 

In Table 3.1 some factors are stipulated that should be considered in the decontamination of meat (European Union, 1996). Spraying with 1.5-2.5% organic acids such as acetic or lactic acid is effectively applied on red meat carcasses (Canadian Food Inspection Agency, 2004). Lactic and acetic acid solutions are commonly used by the red meat slaughtering industry as an antimicrobial spray wash on freshly slaughtered beef carcasses. These spray washes are used in the early steps of beef carcass processing, usually applied to carcasses after hide removal, before and after evisceration, but before chilling (Berry and Cutter, 2000). 

Not many studies have reported on the potential use of organic acids or the salts of organic acids as postprocessing antimicrobials, either individually or combined with other compounds prior to packaging. However,... 

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