T. F. Platonova’s research while affiliated with Marri Laxman Reddy Institute of Technology and other places

When choosing metal packaging for canned tomatoes and in tomato pouring, it is advisable to take into account their corrosiveness, since corrosion of the inner surface is one of the factors affecting the quality of products during storage. To rationalize corrosion testing of metal packaging and materials, it is advisable to use model media instead of food products. It should be borne in mind that, due to the presence in the composition of products of substances that affect the corrosion rate, the corrosiveness of the model environment and the product may vary. The corrosion kinetics of canned tinplate (ELC) in tomato juice and in an aqueous solution containing oxalic and citric acid was studied. The composition of the model medium (0.4% citric acid + 0.3% oxalic acid) was selected based on the results of previous studies. The uniform corrosion rate of ELC was measured by the polarization resistance method, the pitting corrosion rate was measured by zero resistance amperometry. The measurements were carried out using an Expert-004 corrosion meter in automatic mode. The mass of the tin coating on the contact surface of the ELC is 5.5–5.7 g/m2. According to the results of the studies, it was found that the kinetics of the rate of uniform and pitting corrosion of the ELC when interacting with tomato juice is similar to the kinetics of the process when interacting with a model medium. For both the model environment and tomato juice, the corrosion process is uniform - the average stationary pitting rates are 7.5-7.6 times lower than the corresponding values for uniform corrosion (for the model environment – 2.73 and 20.46 ?m/year; for tomato juice - 1.12 and 8.54 ?m/year). At the same time, the corrosiveness with respect to ELC for tomato juice is 2.4 times less than for a model medium. Thus, it is advisable to use a two-component model medium containing 0.4% citric and 0.3% oxalic acid for corrosion testing of metal packaging and materials, taking into account the correction factor.

When choosing metal packaging for canned vegetables, it is advisable to take into account their corrosivity, because the inner surface corrosion is one of the factors affecting product quality during storage. To rationalize the corrosion tests of metal packaging materials, it is advisable to replace food with model media – organic acids solutions. The aim of this work was to study the corrosion kinetics of electrolytic tinplate in model media–aqueous solutions of oxalic (mass fraction 0.25–1.00%) and citric (mass fraction 0.25–1.50%) acids, as well as their compositions. The uniform corrosion rate was measured by the linear polarization resistance method, pitting corrosion–zero resistance amperometry method. The tests were carried out using the “Expert-004” corrosion-meter, according to a two-electrode scheme. For oxalic acid solutions with a mass fraction of 0.25% and 0.50% and for all citric acid solutions, the process is characterized as uniform corrosion – the pitting corrosion rates average steady values are 7–11 times less than the corresponding uniform corrosion rates values (1.52–3.93 µm/year and 17.42–26.56 µm/year, respectively). The most aggressive with respect to tinplate are oxalic acid solutions with a mass fraction of 0.25 and 0.50% and citric acid solutions with a mass fraction of 0.25 and 0.50%. On this basis, two-component solutions of the following composition were chosen: 0.25% citric acid + 0.25% oxalic acid; 0.25% citric acid + 0.50% oxalic acid; 0.50% citric acid + 0.25% oxalic acid; 0.50% citric acid + 0.50% oxalic acid. For these solutions, the process is characterized as uniform corrosion — the pitting corrosion rates average steady values are 7–10 times less than the corresponding the uniform corrosion rates values (2.04–3.85 ?m/year and 19.56–26.93 ?m/year, respectively). For two-component solutions, an additive effect is observed–the uniform and pitting corrosion rates average experimental steady values correspond to the calculated additive values. By mathematical processing of experimental data, it was found that the uniform corrosion steady rate maximum value the corresponds to a two-component solution containing 0.40% citric acid and 0.30% oxalic acid. This is confirmed by experimental data–the uniform corrosion rate average steady value for this solution is 28.18 ?m/year. According to the research results it was found that as a model corrosive medium that simulates canned vegetables, it is advisable to use a solution containing 0.40% citric acid and 0.30% oxalic acid, because it is the most aggressive.

Because of the metal packaging corrosion, during storage of canned food the quality deteriorates.One of the ways to reduction of quality loss and increase the shelf life of canned products is the use of food additives - corrosion inhibitors. From the literary data it is known that pectin and gelatin are corrosion inhibitors whose action is based on adsorption to the metal surface.Besides the usual gelatin, in the work we used hydrolyzed gelatin, which does not increase in the viscosity of the liquid phase.The aim of the present work was to study the effect of pectin, gelatin and hydrolysed gelatin on the tinplate corrosion rate in the liquid phase of stone fruit compotes (cherries, merries, peaches and plums). The corrosion rate was measured by the method of linear polarization resistance, based on the creating a potential difference between two identical samples of metal and measuring the amperage.The measurements were carried out using the universal automatic corrosion-meter "Expert-004".For all corrosive media, the corrosion rate kinetics is as follows: at the beginning of the test, the maximum corrosion rate of tinplate is observed, which decreases to a stationary value within 24-36 hours. The presence of inhibitors has not effect the kinetics of the process, but the steady-state corrosion rate for the liquid phase of compote from cherries decreased 1.6 - 3 times, for the liquid phase of compote from peaches - by 1.9 times.For the liquid phase of compotes from merries and plums, the application of pectin and hydrolysed gelatin does not has an inhibitory effect.The greatest inhibitory effect for the liquid phase of compotes from cherries is observed when applying 0.5% hydrolyzed gelatin - without an inhibitor, the steady-state corrosion rate of tinplate was 8.3 ?m / year, with the inhibitor - 2.8 ?m / year. According to the results of the study, it was found that in order to reduce quality losses during the storage of stone fruit compotes in a metal package, it is advisable to apply hydrolyzed gelatin in an amount of 0.5% to the mass of the liquid phase.