Pasteurization Units (PU)
Compute the pasteurization units (PU) of a process, PU = t·10^((T − Tref)/z), the lethal time equivalent at a reference temperature. Widely used for beer and juice (Tref = 60 °C, z = 7 °C): a beer needs ~15 PU for microbiological stability. It lets you compare and control pasteurizers operating at different time-temperature combinations. Enter the time, the process temperature, the reference temperature and the z-value.
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Pasteurization units (PU)
Pasteurization does not sterilize — it only cuts the microbial load down to safe levels and extends shelf life, preserving flavor and nutrients better than sterilization does. Pasteurization units (PU) measure the 'dose' of heat treatment: PU = t·10^((T − Tref)/z), the lethal time equivalent at a reference temperature. For beer, the standard is Tref = 60 °C with z = 7 °C, and brewers target roughly 15 PU (a range of 5 to 25, depending on the risk) for microbiological stability without any cooked, pasteurized flavor. A tunnel pasteurizer delivers that by heating the bottles with hot water sprays and summing the PU accumulated in each zone — too much treatment cooks the beer, too little invites contamination. The concept mirrors the F₀ value used in sterilization, only with a milder reference. Enter the time, the process temperature, the reference temperature and the z value.
Related Tools
F₀ Sterilization Value
Compute the F₀ value of a thermal process, F₀ = t·10^((T − 121.1)/z), the equivalent sterilization time at 121.1 °C (250 °F) with z = 10 °C, the reference for Clostridium botulinum. It is the universal 'currency' that compares thermal processes at different temperatures: an F₀ of 3 minutes is the minimum safety for low-acid canned foods (botulinum cook). Enter the time, the process temperature and the z-value.
Microbial Lethality
Compute the lethality rate (L-value) of a thermal process, L = 10^((T − Tref)/z), the factor indicating how many times faster (or slower) microbial destruction at a temperature T is than at the reference temperature. Integrated over time, the lethality gives the process F-value. It is the basis of the general-method sterilization calculation, which sums the lethality over the product's actual thermal history. Enter the temperature, the reference temperature and the z-value.
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The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.