Lecture+19+acid+and+oxygen+_color_

Lecture+19+acid+and+oxygen+_color_ - Acid preservation &...

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FST104 February 27, 2012 Undissociated organic acids (unlike charged compounds and H + ) pass freely into the cell. Food preservation with acids once inside the cell, they can dissociate: organic acids become more ionized as pH increases RCOOH < pKa < RCOO - + H +
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Organic acids for food preservatives Acetic acid (CH 3 COOH) Citric acid and Lactic acid not very effective (remain dissociated until low pHs) anions are not significantly inhibitory anion has inhibitory effects (in addition to action of hydrogen ion) more effective than other organic acids common “pickling’ agent Benzoic acid wide usage sodium benzoate (E211), potassium benzoate (E212) and calcium benzoate (E213) Parabens not very soluble. limited use in food E214, E216, E218 Organic acids for food preservatives Propionic acid widely used to inhibit molds in bakery products legal limit is too low to be effective against yeasts E280 Sorbic acid (2,4-hexadienoic acid) commonly used to prevent yeasts and molds in fermented foods hydrophobic structure gives it very good membrane penetration E200 – E204
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Organic acids in food preservation How much propionic acid is needed to inhibit yeast growth in 100 g of food at pH 5? (taking food weight into account)
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Lecture+19+acid+and+oxygen+_color_ - Acid preservation &...

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