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Canned food aisle at grocery store

Food preservation has been performed for thousands of years in many different ways, and it continues to evolve with advancements in science and technology. Techniques such as salting and curing date back to medieval times, while newer methods include the use of food additives and irradiation. These more modern preservation techniques are more technical and can present more challenges in preservation efficiency.

One of the most popular techniques that has stood the test of time is canning. Canning as a method of preservation can be traced back to the early 1800s. The invention of canning was a result of the French government offering a cash reward for an affordable, efficient means of preserving large volumes of food. At the time, the French government needed a way to increase availability of food supplies for armies fighting in the Napoleonic wars. Inventor Nicholas Appert observed that food cooked in sealed glass jars would not spoil unless the seal was broken.

However, the fragile glass jars proved to be inconvenient for transport, so the use of steel cans for canning was introduced. Often, home cooks can their own fruits and vegetables by packing them into glass jars, heating, and finally sealing them to prevent the growth of bacteria. Industrial canning primarily uses tin-coated steel cans or aluminum cans. These cans are internally coated with an epoxy resin to prevent the leaching of metals into the food. In conjunction with the canning process itself, chemical additives are frequently used to further prevent degradation of the product.

While the heat and pressure used during canning extends the shelf life of foods, manufacturers may still add preservatives like sulfites and calcium chloride to further increase longevity, retain freshness, and improve texture. Calcium chloride (CaCl₂) is used in a wide variety of food products including cheese, tofu, and sports drinks because of its effectiveness as an anti-caking agent, stabilizer, and thickener. Calcium chloride can be used to adjust for mineral deficiencies during the cheese making process or even during beer brewing. Canned vegetable and pickle manufacturers often use calcium chloride as a substitute for sodium chloride in their brines to lower sodium content but still provide the salty flavor and antimicrobial benefits of salt.


The United States Food and Drug Administration has established guidelines regarding food additives. For calcium chloride, the maximum allowable levels vary based on the food type. For example, baked goods may only contain 0.3 % calcium chloride; in jams and jellies, only 0.1 % percent is allowable. Due to the strict standards set by the Federal Code of Regulations, manufacturers must be certain that the calcium chloride content of their products comply with FDA regulations. Additionally, calcium chloride is monitored for quality control purposes to ensure consistency between batches.

A canned foods manufacturer contacted Hanna Instruments interested in testing the calcium chloride content of their canned tomatoes. Their goal was to meet the FDA regulations of 0.4% CaCl₂ and follow their internal quality control standards. The customer’s primary focus was to obtain a meter with high accuracy and repeatability. Hanna suggested the Automatic Potentiometric (pH/mV/ISE) Titration System - HI902C with a Calcium Combination Ion Selective Electrode (ISE) - HI4104 for complexometric determination of calcium with EDTA.

The 40,000 step piston-driven pump delivered precise titrant doses into their tomato samples, yielding better results than with a manual titration. The fast titration time ensured they met their production deadlines and allowed them to do more frequent testing for better quality control. The HI902C can store up to 100 methods, enabling the operator to create and optimize various titration methods to suit specific sample types. The customer appreciated this, as they produced other tomato-based foods which also required analysis. Overall, the HI902C gave the manufacturer an accurate, reliable means of measuring calcium chloride in their products allowing them comply with FDA standards and produce a consistent, high quality product.

If you found this post useful check out our post on Determining Tomato Maturity by Measuring pH