food preservation

Pickled or pickled - Food storage

Preservation in vinegar (also written in vinegar) indicates two distinct types of food processing, both characterized by the exclusive presence of natural ingredients: while the first is based on intrinsic lactic fermentation, the second involves the addition of an external acid component ( vinegar) to a pre-cooked food.

Fermented vinegar

Fermented vinegar is a food (vegetable) subjected to microbial proliferation; the biological starter is constituted by the microorganisms naturally present on the vegetable and the conservative agent is constituted by the lactic acid; the most common fermented pickles are sauerkraut and gherkins.

The production technique is more or less the same for both pickled vegetables, and even the microbial cultures involved are almost the same; both the sauerkraut and the fermented gherkins exploit the action of some lactic bacteria such as L. mesenteroides, E. faecalis, P. cerevisiae, L. brevis and L. plantarum ; among all, the pedicocchi and L. plantarum are the most important, while L. brevis (especially for gherkins) is a potentially harmful species.

The fermented vinegar requires (after washing, trimming and cutting) the addition of cooking salt (NaCl), useful for selecting the suitable microbial colony for the process (since in this way only the bacteria necessary for the activation will be activated). release of lactic acid). NB : if the bacterial selection fails, softening, decay, swelling, discoloration, viscosity, etc. may occur.

Vinegar with addition of vinegar

The vinegar is another "natural" food preservation technique (especially vegetables, mushrooms and fish) previously washed, cleaned, pre-cooked and immersed in a boiling ACID liquid, with a food pH of about 4.6; it is a predominantly "chemical" conservative method, more artifact than the previous one and obtained by the addition of food vinegar (the wine vinegar, for example, contains about 6% acetic acid - CH3COOH). The choice of a pH of 4.6 represents the right compromise between the palatability of the vinegar (which has characteristic acidulous taste and aroma) and its hygienic safety, because:

the bacteria develop mainly at a pH of 6.5-7.5, molds at about 6, and yeasts in a range of pH fluctuating between 3 and 4 (therefore being potentially active in the non-sterilized vinegar). However, by pre-cooking and subsequently immersing the vinegar in the boiling liquid, it is possible to reduce the microbial load (including yeasts!) To such an extent that it will almost totally prevent its growth in the preserved food.

Despite the acetic acid has antibiotic properties, for the most perishable preparations it is advisable to fortify the antiseptic / bactericidal effect with the addition of table salt (sodium chloride - NaCl) and spices; these ingredients represent further natural conservation factors useful for prolonging the life of the food ( Obstacle theory - see NOTES ). On the other hand, the concentration of acetic acid in the vinegar may vary depending on the type of food stored; for example, on the label of a commercial vinegar we can distinguish 3 different wordings1:

  • Flavored with vinegar: if the acidity of the vinegar governing liquid is less than 1.2%
  • With vinegar or vinegar: if the acidity of the liquid is more than 1.2%

  • In vinegar: if the acidity of the liquid is more than 2.2%.

Sweet and Sour Crunchy Pickled

X Problems with video playback? Reload from YouTube Go to Video Page Go to Video Recipes Section Watch the video on youtube

Nutritional aspects

From a nutritional point of view, pickled foods prepared by adding vinegar do not differ much from those cooked and ready to eat. The only useful reflection concerns: the possible vitamin loss resulting from the pH change, the eventual saline loss due to dilution in the liquid, and the eventual undesirable increase in the food sodium in the event salt is added.

With regard to fermented pickled foods, they enjoy an increase in choline and cobalamin (vit. B12) by microbial action, while there is a parallel decrease in vitamin C (ascorbic acid) in the food. Also in this case, by addition in the preparation, the sodium intake increases in an undesirable manner.

NB . Some believe that the pH of the vinegar can somehow affect the integrity of the gastric mucosa; in reality, the anti-acid barrier of the stomach is prepared to withstand acid concentrations that oscillate from a pH of 1 to 3, therefore, a value of 4.6 should not affect in any way.

NOTES: Theory of obstacles : the theory of obstacles is a principle of food preservation for which, in order to obtain greater conservative safety, action is taken on several levels with respect to a single variable (reduction of food water + salting + under 'vinegar + essential oils of spices etc.). In this way the risks of applying a single treatment are reduced and the quality (healthiness) of the food is improved.

Bibliography:

  • Food microbiology - James M. Jay, Martin J. Loessner, David A. Golden - Springer - pages 191-192
  • Food and health. Food feeding course - S. Rodato, I. Gola - Clitt - pag 275; 292.