SOP: Allowance for Retort Come-Up Time in Process Time

GIFSQ — Global Institute for Food Safety & Quality

Principle

Recommendations of time at a given temperature normally ignore the retort come-up time. With static retorts having an appreciable come-up time, a proportion of it — usually 40% — may be allowed as process time, and the actual process time is reduced accordingly.

Materials required

• The calculated process time uncorrected for retort come-up time
• The measured retort come-up time (time in minutes required to bring the retort to processing temperature)

Procedure

Note the process time calculated without correction for the retort come-up time (Bₚ)

↓

Note the time in minutes required to bring the retort to processing temperature (J)

↓

Calculate the actual process time using the formula below

Calculation

P꜀ = Bₚ − (0.4 × J)

Where,

• P꜀ = actual process time
• Bₚ = process time uncorrected for retort come-up time
• J = time in minutes required to bring the retort to processing temperature

Precautions

• This correction is required only for still retorts; it does not apply to agitated retorts or continuous cookers.

References

Ranganna, S., Handbook of Analysis and Quality Control for Fruit and Vegetable Products, 2nd edition.