Blanching Time Calculator Formula

Understand the math behind the blanching time calculator. Each variable explained with a worked example.

Formulas Used

Blanching Time

blanch_minutes = round(vegetable * altitude_factor * 10) / 10

Water Needed

water_quarts = ceil(batch_lbs) * 1

Ice for Ice Bath

ice_lbs = ceil(batch_lbs)

Variables

VariableDescriptionDefault
vegetableVegetable Type3
altitude_factorAltitude1
batch_lbsBatch Size(lbs)2

How It Works

How to Blanch Vegetables

Process

1. Bring a large pot of water to a rolling boil (1 quart per pound of vegetables). 2. Add vegetables and start timing when the water returns to a boil. 3. Blanch for the recommended time. 4. Immediately transfer to an ice bath for the same duration to stop cooking. 5. Drain well and proceed with freezing, dehydrating, or canning.

Why Blanch?

Blanching inactivates enzymes that cause loss of flavor, color, and texture during frozen storage. It also helps preserve vitamins and cleans the surface of the produce.

Altitude Adjustment

At higher elevations, add 15% time above 3,000 ft and 30% above 6,000 ft because water boils at a lower temperature.

Worked Example

2 lbs of green beans at sea level.

vegetable = 3altitude_factor = 1batch_lbs = 2
  1. 01Base blanching time = 3 minutes
  2. 02Altitude factor = 1 (sea level)
  3. 03Adjusted time = 3 x 1 = 3 minutes
  4. 04Water needed = 2 quarts
  5. 05Ice bath = 2 lbs of ice, blanch in ice water for 3 minutes.

Ready to run the numbers?

Open Blanching Time Calculator