While residents of most midwestern states usually don’t think about their elevation, elevation affects all aspects of food preparation–cooking, baking, canning, jams and jellies, and candy making. As elevation rises, air pressure falls and water boils at lower temperatures making recipe adjustments necessary.
Elevation and Everyday Cooking and Baking
When it comes to everyday cooking and baking, there are few noticeable effects of elevation until one reaches 3,000 feet. Higher elevations present several challenges when preparing some foods. At higher elevations, leavened products using yeast, baking powder/soda, egg whites, or steam rise more rapidly, may collapse, and may not be fully cooked. Because water boils at a lower temperature at higher elevations, foods that are prepared by boiling or simmering will cook at a lower temperature, and it will take longer. High elevation areas are also prone to low humidity, which can cause the moisture in foods to evaporate more quickly during cooking. At elevations above 3,000 feet, preparation of food may require changes in time, temperature or recipe. For those that find themselves at higher elevations, Colorado State University and New Mexico State University have excellent tips and guidelines for successful baking and cooking.
Elevation and Canning Safety
Because water boils at 212°F at sea level and decreases about 1°F for each 500-ft increase in elevation, adjustments must be made when canning foods at home to ensure home-canned foods are processed safely. The amount of time that jars are held at a certain temperature during canning is important to producing a safe product. Processing times for most recipes are based on elevations of 0-1,000 feet unless stated otherwise. When elevations are above 1,000 feet, extra time is added for food processed in a water-bath canner. For food processed in a pressure canner, extra pressure is added. Both adjustments are needed to get to their respective safe processing temperatures for high acid and low acid foods.
USDA and National Center For Home Food Preservation (NCHFP) recipes include a table for proper processing based on elevation to insure sufficient time and temperature have been reached for a safe, shelf-stable product. In the table for Crushed Tomatoes from the USDA Compete Guide to Home Canning, 2015 edition, note that time is increased in 5 minute increments as elevation increases for boiling water canning and pounds of pressure is increased for pressure canning. (Crushed tomatoes are one example of a food that can be processed by either boiling-water bath or pressure.)
While time is adjusted for water-bath canning, pressure regulation differs by the type of pressure canning equipment used—dial- or weighted-gauge canner.
Elevation and Sugar Concentrations
Elevation is also a factor in candy making and the gelling of jams and jellies when pectin is not used. At higher altitudes, atmospheric pressure is less so water boils at lower temperatures and evaporates more quickly. Syrups become concentrated and reach the gel point at a lower temperature. The concentration of sugar required to form a gel is in the range of 60 to 65 percent which occurs at 217 and 220 degrees F, respectively, at sea level. As elevation increases, the gelling point decreases by 2 degrees per 1,000 feet. When elevation is not taken into consideration, overcooked jam is the result as too much water has boiled away leaving a sugar concentration that is too high, leaving a jam that is gummy, dark in color or tough. The same is true for candy making. For each 1,000 feet above sea level, reduce the temperature in the recipe by 2 degrees F to prevent overcooking. Colorado State University provides a High Elevation Candy Making (Sugar Solution) Adjustment chart for various kinds of candy mixtures.
Find and Know Your Elevation
Elevation matters in all aspects of food preparation. It is especially important for the safety of home canned products beginning at elevations above 1,000 feet. Before beginning the canning process or making sugar concentrations, find your elevation using one of these sources to insure proper processing of canned products and prevent overcooking of jams and candies:
- Visit a web page about your town or city.
- Use an online tool such as What is my elevation?
- Use a smartphone app such as My Elevation.
- Refer to an elevation map for your state showing approximate elevations such as this one by Iowa State University Extension and Outreach from the Preserve the Taste of Summer series.
To learn more about elevation, watch this YouTube video by UNL Extension Food & Fitness.
To learn more about safe water-bath or pressure canning practices, watch these videos produced by South Dakota State University: