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, where 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 aluminium 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 sulphites 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, stabiliser, 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 flavour and antimicrobial benefits of salt.
Due to the strict standards set by the governmental regulations, manufacturers must be certain that the calcium chloride content of their products comply with them. 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 regulations of 0.4% CaCl₂ (FDA, US) and comply with their internal quality control standards. The customer already had a production laboratory established to test for other parameters, so their primary concern was obtaining a meter with high accuracy and repeatability. Hanna suggested the HI902 Automatic Titration System with an HI4104 Combination Calcium Ion Selective Electrode 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 HI902 can store up to 100 methods, enabling the operator to create and optimise 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 HI902 gave the manufacturer an accurate, reliable means of measuring calcium chloride in their products allowing them to comply with governmental standards and produce a consistent, high quality product.