Purpose: We evaluated a hot-fill-hold process by assessing the effect of process conditions on accumulated lethality values measured on the underside of the lid and vacuum formation, and modeled the conditions’ effects.
Methods: Sucrose solutions (10 to 50°Brix) were prepared and heated (79.4 to 96.1°C). Glass canning jars (473 and 946 ml) were used, with two lid widths (regular and wide). After hot-filling, the temperature on the underside of the lid (coldest point in the container) was measured for 5 min using a surface thermocouple. After cooling at room temperature container vacuum was measured. A full factorial design was used to test the effects of sucrose concentration, filling temperature, jar size and lid width on the logarithmic transformation of accumulated lethality and vacuum formed. Multiple linear regression analysis was performed and significant (P < 0.001) terms of the model selected. Experiments were conducted in triplicate.
Results: Regression analyses (R2 > 0.98) showed that all three- and four-way, and most two-way interactions were not significant in both models. Sorted parameter estimates showed that the solution’s temperature and jar size had the most significant effect on the responses lethality and vacuum, respectively. Overall, lethality values ranged between 0.001 and 0.1 min (Tref 93.3°C, z-value 8.9°C), and vacuum between 20 and 60 kPa.
Significance: These results contribute to the establishment of processing guidelines ensuring production of safe and stable products with optimized processing temperatures and times to enhance quality of hot-fill-hold products.