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Antimicrobial Preservation Overview<br />Jim McElroy<br />
Composition and Structure of Microorganisms<br />The cell surface differentiates cells from one another<br />The cell enve...
Cell membranes<br />Main components are phospholipids and proteins<br />Major proteins are hydrophobic<br />The plasma str...
Comparison<br />
Yeast and Mold<br />Yeast: Cell wall is composed of two or more protein polysacharide complexes held together by covalent ...
Comparison (bacteria, yeast & mold)<br />
What is a preservative?<br />	A chemical substance that is used to preserve pharmaceuticals, food or other organic materia...
Commonly used preservatives <br />Ingestible & Topical<br />Methyl, ethyl, propyl and butyl Parabens<br />Sorbic acid <br ...
Parabens<br />	Parabens are among the most commonly used preservatives. They are relatively active against a broad spectru...
Parabens and pH<br />	Parabens disassociate at high pH (8 or more) and are rendered ineffective. <br />
Parabens have limited solubility in H2O<br />
Partition Coefficients and Emulsions<br />	It is important to pay close attention to preservative partitioning in emulsion...
Partitioning of Parabens<br />Parabens are lipophilic.  <br />Parabens will partition disproportionately into the oil phas...
Partition Coefficient Measurement<br />Cw is the preservative left in the water phase<br />C is overall % of preservative<...
Partition Coefficients For Parabens & Other Preservatives<br />
Chelating Agents as Preservative Enhancers<br />	Alkaline earth metals such as Ca+ and Mg+ are important for the stabiliza...
Ingredients That Enhance Preservative Efficacy<br />Solutes (salts & high concentration of sugars)<br />Esters<br />Cation...
Ingredients That Hinder Preservative Efficacy<br />Sugars and alcohol sugars<br />Proteins, peptides, yeast extract<br />N...
Manufacturing Steps That Enhance Preservative Efficacy<br />Sanitary condition of equipment<br />Treatment of raw material...
Packaging Components and Preservative Efficacy<br />Design of opening or dispenser<br />Susceptibility to contamination fr...
Conclusion<br />	It is important to take into consideration all aspects of the formula before considering a preservative s...
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Antimicrobial Preservation Overview

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This is a nice overview of preservation of food and medical products

Published in: Health & Medicine

Antimicrobial Preservation Overview

  1. 1. Antimicrobial Preservation Overview<br />Jim McElroy<br />
  2. 2. Composition and Structure of Microorganisms<br />The cell surface differentiates cells from one another<br />The cell envelope is the rate limiting barrier for the partitioning of :<br />Nutrients<br />Waste products<br />Chemicals<br />
  3. 3. Cell membranes<br />Main components are phospholipids and proteins<br />Major proteins are hydrophobic<br />The plasma structure is stabilized by hydrogen bonding<br />Mg2+ and Ca2+ cations stabilize the membrane<br />
  4. 4. Comparison<br />
  5. 5. Yeast and Mold<br />Yeast: Cell wall is composed of two or more protein polysacharide complexes held together by covalent bonds<br />Yeast: Mannan is a cell wall component<br />Mold: Cell wall is composed of two or more protein polysaccharide complexes held together by covalent bonds<br />Mold: Mannan is not a cell wall component<br />
  6. 6. Comparison (bacteria, yeast & mold)<br />
  7. 7. What is a preservative?<br /> A chemical substance that is used to preserve pharmaceuticals, food or other organic material from decomposition or fermentationby preventing the growth of microorganisms.<br />
  8. 8. Commonly used preservatives <br />Ingestible & Topical<br />Methyl, ethyl, propyl and butyl Parabens<br />Sorbic acid <br />Na, K & Ca Sorbate<br />Benzoic acid<br />Na, K & Ca Benzoate<br />Sodium metabisulfite<br />Propylene glycol (15-30%)<br />BHT, BHA<br />Flavors w/ benzaldehyde<br />Topical Only<br />Formaldehyde donors<br />Essential Oils<br />Monoglyceride <br />Phenol<br />Mercury compounds<br />
  9. 9. Parabens<br /> Parabens are among the most commonly used preservatives. They are relatively active against a broad spectrum of microorganisms. The methyl ester is most effective against bacteria and molds while the ethyl, propyl and butyl esters are more active against yeast and molds. Parabens are more effective against gram negative than gram positive organisms.<br />
  10. 10. Parabens and pH<br /> Parabens disassociate at high pH (8 or more) and are rendered ineffective. <br />
  11. 11. Parabens have limited solubility in H2O<br />
  12. 12. Partition Coefficients and Emulsions<br /> It is important to pay close attention to preservative partitioning in emulsion systems. Parabens prefer the oil phase thus leaving little in the water phase where it is needed.<br />Water phase<br />Oil droplet<br />surfactant<br />
  13. 13. Partitioning of Parabens<br />Parabens are lipophilic. <br />Parabens will partition disproportionately into the oil phase of an emulsion. <br />If large amounts of the preservative partition into the oil phase, it is not available for antimicrobial action.<br />
  14. 14. Partition Coefficient Measurement<br />Cw is the preservative left in the water phase<br />C is overall % of preservative<br />Kw is the partition coefficient<br />ά is phase volume ratio<br />Cw=C* ά + 1 / Kw + 1<br />
  15. 15. Partition Coefficients For Parabens & Other Preservatives<br />
  16. 16. Chelating Agents as Preservative Enhancers<br /> Alkaline earth metals such as Ca+ and Mg+ are important for the stabilization of the outer membrane of cellular organisms. Chelating agents sequester these ions. This contributes to the partial solubilization of the cell membrane which allow preservatives a pathway into the cell. EDTA is a typical chelating agent used in formulations.<br />
  17. 17. Ingredients That Enhance Preservative Efficacy<br />Solutes (salts & high concentration of sugars)<br />Esters<br />Cationic and anionic surfactants<br />Humectants (glycerin, propylene glycol)<br />Phenolic antioxidants (BHT)<br />Chelating agents (EDTA)<br />Fragrances<br />Low water activity<br />
  18. 18. Ingredients That Hinder Preservative Efficacy<br />Sugars and alcohol sugars<br />Proteins, peptides, yeast extract<br />Natural gums & cellulose thickeners<br />Plant extracts (aloe vera, starch,…)<br />Vitamins<br />Clay compounds<br />High water activity<br />Surfactants (Tween 80)<br />
  19. 19. Manufacturing Steps That Enhance Preservative Efficacy<br />Sanitary condition of equipment<br />Treatment of raw materials<br />Heat treatment of sub-phase or final batch<br />Sub-micron filtration<br />Hot fill<br />Aseptic fill<br />
  20. 20. Packaging Components and Preservative Efficacy<br />Design of opening or dispenser<br />Susceptibility to contamination from environment<br />Susceptibility to contamination from human contact<br />
  21. 21. Conclusion<br /> It is important to take into consideration all aspects of the formula before considering a preservative system. This includes type of formula, bulk handling and packaging.<br />

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