To compare the consequences of water hardness on canning of dry beans, baked beans were prepared using water that contained 70 or 260 ppm calcium for soaking/blanching of navy beans and in the preparation of a tomato sauce for brine. Another factor examined for this project involved increasing the initial temperature of the canned beans prior to thermal processing by eliminating the cooling step after blanching. In general, if the initial temperature prior to thermal processing can be increased, the process time (Bb) is generally decreased. However, when the initial temperature of these baked beans was increased by this method, the process time increased in comparison to the time for beans that were cooled after blanching. In examining the water hardness, the beans, which had been cooled after blanching, processed with an increased CaCO3 demonstrated a decreased process time (Fo = 5.3) in comparison to those beans processed with a lower CaCO3. In one instance, the process time was decreased by 12% due to the presence of calcium possibly due to decreased gelatinization, physical restriction of swelling, reduced solubility of pectin, starch, and protein in the brine solution; consequently, these actions would increase the heat transfer in the food during thermal processing. Based on these investigations, water hardness should be considered an important parameter when performing heat-processing determinations and in the transference of heating data from one site to another.
1Mr. Jackson is Vice President of Research and Development, Heekin Can, Inc., 8200 Broadwell Road, Cincinnati, OH 45244.