Sterilization Temperatures

[GIJoe]

I was too lazy to hunt this down myself, so here it is as originally posted by Big-Golden

Originally posted by Big-Golden

I got this off a homebrew website... by homebrew I mean Beer. ( Yes, I make my own )

Oven
Dry heat is less effective than steam for sanitizing and sterilizing, but many brewers use it. The best place to do dry heat sterilization is in your oven. To sterilize an item, refer to the following table for temperatures and times required.

Table 3 - Dry Heat Sterilization

Temperature Duration

338°F (170°C) 60 minutes

320°F (160°C) 120 minutes

302°F (150°C) 150 minutes

284°F (140°C) 180 minutes

250°F (121°C) 12 hours (Overnight)

The times indicated begin when the item has reached the indicated temperature. Although the durations seem long, remember this process kills all microorganisms, not just most as in sanitizing. To be sterilized, items need to be heat-proof at the given temperatures. Glass and metal items are prime candidates for heat sterilization.

Some homebrewers bake their bottles using this method and thus always have a supply of clean sterile bottles. The opening of the bottle can be covered with a piece of aluminum foil prior to heating to prevent contamination after cooling and during storage. They will remain sterile indefinitely if kept wrapped.

One note of caution: bottles made of soda lime glass are much more susceptible to thermal shock and breakage than those made of borosilicate glass and should be heated and cooled slowly (e.g. 5 °F per minute). You can assume all beer bottles are made of soda lime glass and that any glassware that says Pyrex or Kimax is made of borosilicate.


Autoclaves and Pressure Cookers

Typically when we talk about using steam we are referring to the use of an autoclave or pressure cooker. These devices use steam under pressure to sterilize items. Because steam conducts heat more efficiently, the cycle time for such devices is much shorter than when using dry heat. The typical amount of time it takes to sterilize a piece of equipment in an autoclave or pressure cooker is 20 minutes at 257° F (125 °C) at 20 pounds per square inch (psi).