![]() In addition to the presence of a range of buffering components such as proteins and amino acids, the issue may be further complicated by the presence of oil or fat into which the acid might partition preferentially. While it is relatively straightforward to calculate the effect on pH of dissolving known concentrations of an acid in water and, knowing the pH, to calculate degree of dissociation of a weak acid using the Henderson–Hasselbalch equation, it is not possible to make such simple calculations of the pH resulting from addition of a weak acid such as ethanoic to the complex and ill-defined buffering system in a food. In many traditional products the effect of the former is mitigated by osmotic dehydration (salting) or drying of raw materials prior to pickling. The efficacy of acid solutions, such as vinegar, added to foods will be reduced by the diluting effect of the food’s water content and by its intrinsic buffering capacity. Addition of vinegar to a food material can thus considerably reduce its pH, inactivate some of its indigenous microflora and restrict the growth of those that survive. † Vinegar can be produced with ethanoic acid concentrations in excess of 10% (most table vinegars would contain 4–5% w/v) and was the strongest acid known in antiquity. It is produced by a double fermentation process in which sugar is first converted into ethanol by yeast and a second aerobic stage in which acetic acid bacteria oxidize the ethanol to ethanoic acid. The preserving power of vinegar is due to its high content of ethanoic acid. ![]() Lemon and lime juice, which contain citric acid, are used in products such as ceviche, some salad dressings and pickles, but traditional procedures to acidify foods and confer keeping quality and safety usually employ acids of microbial origin. Phosphoric acid, a relatively strong acid, is an important ingredient in soft drinks such as colas. Adipic, citric, ethanoic, fumaric, gluconic, lactic, malic, succinic and tartaric acids are available commercially and are permitted for use as food acidulants, and acid preservatives such as benzoic acid and sorbic acid can be added to a range of food products such as jams, bread and cakes. ![]() Lactic acid produced by endogenous enzymatic activity is responsible for the postmortem acidification of meat. Citric, malic and tartaric acid, among others, occur naturally in fruits and vegetables. Adams, in Food Safety Management, 2014 Acidity and FoodsĪcids are common components of food systems.
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