H.H. Garner and E.L. Andress, Department of Foods and Nutrition, The University of Georgia, 208 Hoke Smith Annex, Athens, GA 30602-4356.
Paper 46B-6. Presented at the Institute of Food Technologists Annual Meeting Anaheim, CA, June 17, 2002.
Pickled vegetables are popular home preserved condiments. The increasing variety of produce in the marketplace offers opportunities for greater diversity in condiments such as salsa and relishes than has traditionally been available in the U.S. Jicama was studied for its potential use in home pickled products with a crisp texture. The objective of this study was to determine the effect of typical consumer procedural variations on heat penetration when processing an acidified jicama relish recipe. Variations were made in fill weight and initial temperature (IT) of the filled jars. An original recipe with an equilibrium pH of 3.5 was developed for heat penetration studies using a hot pack, pint jars and boiling water canner. Product temperatures were continuously recorded at the predetermined cold spot throughout come-up time, 35 minutes in boiling water, and air cooling of jars. Fifteen jars (five jars in each of three canner loads) were used for each procedural variation of fill weight and IT. Processing was done in a 17-quart boiling water canner on a household gas range. Fill weight had a significant impact on both maximum jar temperature obtained and final process time recommendation. Heat applied during come-up had no effect on jar temperature with the overfill. A decrease of 5°C (64.5 vs. 69.7) in IT had no effect on either maximum jar temperature reached at the end of come-up or the 35 minutes at boiling. However, analysis of the maximum jar temperature reached at the end of come-up or the 35 minutes at boiling. However, analysis of the worst case low IT jar would result in a longer process time than for the higher IT product. This study documents the effects of some consumer practices on process lethality for a cubed relish product. Overfills should be avoided to insure expected heating rates and final maximum temperatures. Specifying a minimum number of jars to a home canning recipe could be considered.
A thermal process (home canning) recommendation was developed for pint jars of an original pickled vegetable relish (jicama, red and yellow bell peppers, onion, hot pepper, spices and vinegar/sugar brine), see Figure 1 (Garner and Andress, 2001). Determination of the cold spot for this product and jar combination was made using data collected for heat penetration curves at 5 potential cold spot locations in the jars in 12 canner loads, see Table 1.
Two levels of two procedural variations were used in testing for process calculations. Temperature profiles were compared for two fill weights (454g, 490g) and two fill temperatures (69.7°C, 64.5°C) of the relish. A total of 12 to15 data points (replications) at the determined cold spot were used for the process calculation. This was accomplished by using thermocouples in each of five jars in three different canner loads of each of the three fill methods (standard, low initial temperature, and overfill).
A total of 15 data points (replications) at the determined cold spot were used for the process calculation. This was accomplished by using thermocouples in each of five jars in three different canner loads of each of the three fill methods (standard, low initial temperature and overfill).
Processing was done in a boiling water canner using the stovetop burners of a household gas range (Magic Chef model 3267XTW). Data were recorded using an Ellab E-Val™ Monitoring System and software and Ecklund needle Type T copper-constantan thermocouples. Analysis of variance was used to determine if significant (p<0.01) differences existed between the treatments using the General Linear Model procedure in SAS 8.2 (2001).
|Thermocouple Height in Pint Jar||Average
|n = 12|
|Center||29.5A1||24.6 - 34.1||2.9|
|½" Below Center||37.3B||32.3 - 41.4||2.9|
|1" Below Center||35.7B||30.7 - 40.2||2.9|
|1½" Below Center2||40.2B||37.2 - 44.0||1.9|
|2" Below Center||37.5B||34.4 - 43.6||2.8|
|1 Values with different letters in the
same column are significantly different at p<.001.
2 Location of cold spot, as determined by largest individual f(h) value (worst-case scenario).
|Total Fill Weight (Solids + Liquids)||454 g||490 g||454 g|
|Solids Fill Weight||354 g||472 g||354 g|
|Canner Initial Temperature (n=3)1||82.0 ± 0.6||82.7 ± 0.4||82.2 ± 0.4|
|Jar Initial Temperature||69.7 ± 2.0||73.2 ± 4.2||64.5 ± 2.0|
|Jar Temperature at Start of Boiling||80.4 ± 2.0||72.4 ± 2.5||79.5 ± 2.0|
|Temperature change during come-up time||+ 10.7||- 0.8||+15.0|
|Jar Temperature after 35 Minutes of Boiling2||96.9 ± 0.5||91.3 ± 0.8||97.0 ± 0.3|
|Maximum temperature change during process||+ 27.2||+ 18.1||+ 32.5|
|Maximum Time to Reach 90.5°C3||14||344||16|
|Recommended Process time (time at boiling)5||15||35||20|
|1 Heat penetration data for 12-15 jars were collected from 3 different canner loads.
2 Heat penetration data were collected for 35 mins once the canner was brought to boiling.
3 Values taken from worst-case individual jars; not averages.
4 One jar did not reach 90.5°C until two minutes into the cooling periood; its maximum temperature at the end of 35 minutes of boiling was 89.4°C.
5 Time needed to heat the product to 90.5° for one minute.
|Low Fill Temperature
|Total Fill Weight (Solids + Liquid)||454g||490g||454g|
|Solids Fill Weight||354g||472g||354g|
|Jar Initial Temerature (°C)||69.7 ± 2.0A1||73.2 ± 4.2A||64.5 ± 2.0B|
|f(h)||33.5 ± 2.5A||61.1 ± 2.0B||34.6 ± 2.4A|
|Average Minutes to Reach 90.5°C at Boiling 2||11.3 ± 2.3A||34.8 ± 2.4B3||11.3 ± 2.4A|
|1 Values with different letters in the same
row indicate a significant difference at p<.001.
2Time after water in canner returned to boiling. This comparison of averages is for statistical purposes; in practice, the process time would be determined by the slowest heating individual jar.
3One jar did not reach 90.5°C until two minutes into the cooling period; its maximum temperature at the end of 35 minutes of boiling was 89.4°C.
This material is based upon work supported by the Cooperative State Research, Education, and Extension Service, U.S. Department of Agriculture, under Agreement No. 00-51110-9762.
Permission is granted to reproduce these materials in whole or in part for educational purposes only (not for profit beyond the cost of reproduction) provided the authors and the University of Georgia receive acknowledgment and this notice is included:
Reprinted with permission of the University of Georgia. Garner H.H. and E.L. Andress. 2002. Effect of Fill Weight and Initial Temperature on Processing Time for a Home Pickled Jicama Relish. Athens, GA: The University of Georgia, Cooperative Extension Service.
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