Sorbic acid may be stabilized by phenolic anti-oxidants, for example 0. Owen, 2-Phenylethanol Monograph in: The yeast vacuole is a compartment that allows relatively simple assays in this regard. All contribute to the overall loss of preservative efficacy. Activity is enhanced at acidic pH in the presence of sodium metabisulphite, which can enhance activity at low pH, but has the opposite effect at alkaline pH [34,35].
Synergy is also observed in combination with cetrimide, 3-cresol, chlorhexidine and organo mercurials [6,7]. Don Singer, GSK for their review and comments on this manuscript. EDTA  interacts with thimerosal, propyl gallate and phenylmercuric salts; chlorhexidine  can interact with benzoic acid and cetrimide  is incompatible with phenyl mercuric nitrate.
The main purpose is to first explore the theory of sodium benzoate becoming a new substance when reaching high pH levels. This difference was observed when benzoic acid precipitated out of solution upon addition of HCl.
If the bioburden is low most preservative systems can adequately kill or attenuate growth of most organisms. Owen, 2-Phenylethanol Monograph in: Similarly, m-cresol  is also effective at pHs below its pKa 9.
The substituted benzoic acid derivative thiomersal, which has a pKa of 3. If a precipitate is formed then this will confirm the pH level of the human stomach acid is able to perform the reaction of benzoic acid.
Based on the net equation given in the book as well as the solubility of the product our hypothesis is that a new substance will form. Combining preservatives that act synergistically may help meet performance standards.
Efficacy increases with the longer alkyl chain, but conversely aqueous solubility decreases as hydrophobicity increases . Outside this range growth rate signifi cantly declines.
The pragmatic approach, involving optimizing the preservation system and inclusion levels by conventional assessment techniques therefore remains the desired approach for the present.
Activity needs to be broad spectrum, encompassing bacteria Gram-positive and Gram-negativeyeasts, fungi and molds; but not viruses.
Biguanide anti-microbials are active over the pH range Data, Calculations and results: Strong oxidizing agents degrade sorbic acid , 2-phenylethanol , hexetidine , EDTA , thimerosal , propyl gallate  and butylated hydroxyanisole .
Pharmaceutical products generally have much longer shelf life requirements than food or beverage products and quality must obviously be retained over such periods. The infl uence of partition coefficients, binding constants surfactants and polymersand oil-in-water ratios have all been investigated but with limited success .Start studying The Effect of pH on a Food Preservative.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. Jan 01, · The effect of pH, benzoic acid and sodium chloride concentration on the growth rate of isolates was investigated.
It was found that as the pH of the growth medium increased from 3 to 9, the rate of growth of most isolates also increased except for Pseudomonas cepacia, which had optimum growth at neutral pH 7.
Michael Pitner Chem TA: Gia Hoang Lab 1: Effect of pH on a Food Preservative Purpose The purpose of this lab was to determine if a new substance forms when sodium benzoate is placed in a simulated stomach acid.
Theory Benzoic acid can be found in a wide variety of plants. It is used as a natural preservative in many foods. The consultant’s job was to place the food preservative into a medium that functioned as stomach acid, so sodium benzoate was exposed to an aqueous solution of hydrochloric acid that had a 92%(12).
Start studying Lab 1 - Effect of pH on a food preservative. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The consultant’s job was to place the food preservative into a medium that functioned as stomach acid, so sodium benzoate was exposed to an aqueous solution of hydrochloric acid that had a pH range of one to three%(10).Download