(*Any mention of degrees is in Fahrenheit.)
prepared by Pat Kendall, Colorado State University Cooperative Extension
food science and human nutrition specialist and professor.
TOPICS:
...preparation of food may require changes in time, temperature or recipe. The reason, lower atmosphere pressure due to thinner blanket of air above. At sea level, the presses on a square inch of surface with 14.7 pounds, at 5,000 feet with 12.3 pounds, and at 10,000 feet with only 10.2 pounds - a decrease of about 1/2 pound per 1,000 feet. This decreased pressure affects food preparation in two ways:Return to Topic Index1. Water and other liquids evaporate faster and boil at lower temperatures.
2. Leavening gases in breads and cakes expand more.
The boiling point is the temperature at which the pressure of the water vapor equals atmospheric pressure and the bubbles of water vapor are able to break through the surface and escape into the air. If the atmospheric pressure is less, the temperature required for water to boil is less (Table 1). Therefore, cooking food in water boiling at this lower temperature takes longer. A "3-minute egg" will take more time. Also, a bowl of boiling soup is not as hot.
| Altitude | Temperature |
| Sea Level | 212 degrees F |
| 2,000 ft. | 208 degrees F |
| 5,000 ft. | 203 degrees F |
| 7,500 ft. | 198 degrees F |
| 10,000 ft. | 194 degrees F |
Fruits, tomatoes and pickled vegetables may be canned in a boiling water bath. Because of the lower boiling point of water at high altitude, increase the processing time 1 minute for each 1,000 feet above sea level if the time is 20 minutes or less. If the processing time is more than 20 minutes, increase by 2 minutes per 1,000 feet.Other vegetables, meats and poultry (low-acid foods) must be heated at 240 degrees F for the appropriate time in order to destroy hat-resistant bacteria. A steam pressure canner must be used to obtain a temperature of 240 degrees F. At sea level, 10 pounds of steam pressure will produce this temperature, but at altitudes of 2,000 feet and above, steam pressure must be increased to reach 240 degrees F. The increase is 1/2 pound per 1,000 feet above sea level, as illustrated in Table 2.
| Altitude | Pressure Required |
| Sea Level | 10 lb. |
| 2,000 ft. | 11 lb. |
| 3,000 ft. | 11.5 lb. |
| 4,000 ft. | 12 lb. |
| 5,000 ft. | 12.5 lb. |
| 7,000 ft. | 13.5 lb. |
| 10,000 ft. | 15 lb. |
An important step in preparing vegetables for freezing is heating or "blanching" before packing. Heat 2 minutes longer than the time given for sea level if you live 5,000 feet or more above sea level.Return to Topic Index
To prevent excessive water evaporation, cook the syrup to a final temperature lower than that given for sea level. Decrease the final cooking temperature by the difference in boiling water temperature at your altitude and that of sea level. This is an approximate decrease of 2 degrees for every increase of 1,000 feet in elevation.Return to Topic Index
The lower boiling point of water in foods requires lowering the temperature of the fat to prevent food from over browning on the outside while being under-cooked on the inside. The decrease varies according to the food fried, but a rough guide is to lower the frying temperature about 3 degrees F for every increase of 1,000 feet in elevation.Return to Topic Index
Above 5,000 feet, temperatures obtained with a double boiler are not high enough for maximum gelatinization of starch. Therefore, use direct heat rather than double boiler.Return to Topic Index
High altitude has its most pronounced effect on the rising time of bread. At high altitudes, the rising period is shortened. Since the development of a good flavor in bread partially depends on the length of the rising period, it is well to maintain that period. Punching the dough down twice gives time for the flavor to develop.Return to Topic Index
In addition, flours tend to be drier and thus able to absorb more liquid in high, dry climates. Therefore, less flour may be needed to make the dough the proper consistency.
Most cake recipes perfected for sea level need no modifications up to 3,000 feet. Above that, decreased atmospheric pressure may result in excessive rising, which stretches the cell structure of the cake, making the texture coarse, or breaks the cells, causing the cake to fall. This usually is corrected by decreasing the amount of leavening agent. Also, increasing the baking temperature 15 to 25 degrees "sets" the batter before the cells formed by the leavening gas expand too much. Excessive evaporation of water at high altitude leads to high concentration of sugar, which weakens the cell structure. Therefore, decrease sugar in the recipe and increase liquid. Only repeated experiments with each recipe can give the most successful proportions to use. Table 3 is a helpful starting point. Try the smaller adjustment first, this may be all that is needed.
In making rich cakes at high altitudes, you might have to reduce shortening by 1 or 2 tablespoons. Fat, like sugar, weakens the cell structure. Also, increasing the amount of egg strengthens the cell structure and may prevent the too-rich cake from falling.
| Adjustment | 3,000 ft. | 5,000 ft. | 7,000 ft. |
| Reduce baking powder, for each tsp., decrease: | 1/8 tsp. | 1/8-1/4 tsp. | 1/4 tsp. |
| Reduce sugar, for each cup, decrease: | 0-1 Tbsp. | 0-2 Tbsp. | 1-3 Tbsp. |
| Increase liquid, for each cup, add: | 1-2 Tbsp. | 2-4 Tbsp. | 3-4 Tbsp. |
The leavening gas for these is largely air. Do not beat too much air into the eggs. Beat egg white only until they form peaks that fall over - not stiff and dry, which will cause collapse of cells. Strengthen cell structure by using less sugar and more flour, and a higher baking temperature.Return to Topic Index
Adjustments usually take the form of strengthening the cell walls of the cake by adding all-purpose flour and liquid. Suggestions for high-altitude adjustments are provided on most cake mix boxes. Follow these suggestions.Return to Topic Index
Although many sea-level cookie recipes yield acceptable results at high altitudes, they often can be improved by a slight increase in baking temperature; a slight decrease in baking powder or soda, fat and/or sugar; and/or a slight increase in liquid ingredients and flour. Many cookie recipes contain a higher proportion of sugar and fat that necessary, even at low altitudes.Return to Topic Index
Quick breads vary from muffin-like to cake-like in cell structure. Although the cell structure of biscuits and muffin-type quick breads is firm enough to withstand the increased internal pressure at high altitudes without adjustment, a bitter or alkaline flavor may result from inadequate neutralization of baking soda or powder. When this occurs, reducing the baking soda or powder slightly will usually improve results.Return to Topic Index
Quick breads with a cake-like texture are more delicately balanced and usually can be improved at high altitudes by following the adjustment recommendations given for cakes.
Not generally affected by altitude. However, slightly more liquid may be used.Return to Topic Index
1. Flour, use any brand of enriched all-purpose flour (or cake flour, if called for by the recipe).Return to Topic Index
2. Do not assume that your sea level recipe will fail. Try it first. It may need little or not modification.
