Influence of Product-entrapped Air and Venting on Lethal Effect in Model Domestic Pressure Canner Studies

Effects of entrapped air during thermal processing on lethal effect were evaluated in three domestic canners with quart mason jars. Entrapped air volumes in ceramic-bead products were established with various fillings of water into a dry matrix. Alternate periods of venting included 5, 10, and 15 mins. Process pressure was monitored throughout each of the 54 runs. Venting times and lack of continuous venting demonstrated little impact. Higher lethal effects were noted when the least product-entrapped air was modeled. Differences were noted between pressure processes monitored by the dial gauge versus the calibrated weighted-devices with more variation of the dial gauge system due to the manual control basis.