***NOTE*** This method puts garlic (a known vector for botulism) into an anaerobic cooking environment…which gives it the potential to produce botulinin toxin, if the bacteria C. botulinum is present on the cloves. Followed correctly, this method largely minimizes the risk, and botulism is EXTREMELY rare. Still, it can be deadly, so for those wanting to maximize food safety, see the “SAFEST METHOD” listed at the bottom of the recipe, for extra steps. This is how I do it.
In an oven-safe pot, place:
1-3 cups whole, peeled garlic cloves
Season with a little salt and pepper, and cover with olive oil. Place an oven-safe lid on the pot, and place in a 200F/93C oven for 6 hours. Cool, strain off and reserve the oil, and place both garlic cloves and oil in the fridge if not using immediately.
Consume the garlic within 7 days, and use the oil in an application that sees heat (saute, roast, bake).
WHY THIS IS BETTER THAN TRADITIONAL ROASTING
Traditional roasted garlic is enclosed in foil or parchment and roasted at 350F/175C or above for about an hour. This heat profile and duration is problematic. Our goal in roasting garlic is a complex, sweet, nuanced end result, which is best achieved through INACTIVATION of the enzyme Alliinase (which begins to denature at 107F/42C), and encouraging enzymatic activity of the enzyme Amylase, which loves temperatures of 90-160F (32-71C), and denatures above 165F/74C.
Alliinase converts an innocuous flavor compound in garlic, called Alliin, and turns it into a harsh, acrid, pungent chemical called Allicin. This is the flavor of crushed or sliced fresh garlic, and it is garlic’s defense mechanism from being dug up and consumed by wild animals. Destroying Alliinase means the Alliin remains palatable and muted, and it cannot turn into pungent Allicin, and we get rid of most of the Alliinase when the garlic’s internal temperature gets above 107F/42C.
Amylase is a common enzyme that takes the starches in the garlic (polysaccharides) and breaks them down into the compontent fructose-based sugars, which are sweet. Giving Amylase a long time in its comfort zone means the garlic is sweeter, those fructo-saccharide sugars can further break down and caramelize into complex, sweet compounds. Amylase loves 90-160F (32-71C), but denatures above 165F, so the traditional heating method of 350F/175C quickly exceeds the temperature at which Amylase dies, and it has precious little time to do its work. At 200F/93C, immersed in oil inside a closed pot, it takes a few hours to exceed 165F/74C, giving Amylase plenty of time to convert the starches to sugars, and then continues on above 176F/80C, which is where we start killing any potential Botulism toxin that may have been produced earlier in the cooking process.
UNDERSTANDING THE RISK OF BOTULISM
Fresh garlic is a know vector for Clostridium botulinum, a very common soil bacteria. When spores of C. botulinum are placed in an anaerobic (ie devoid of oxygen) environment and held above refrigeration temperatures, they can produce this toxin. But this toxin can be destroyed, if it has been produced, by heating the food to 176F/80C for 20-30 minutes, or to 185F/85C for 5 minutes…which the method above does achieve. (While the SPORES, themselves, are not killed at that temperature, the spores are harmless if consumed. But if they had previously produced any toxin, heating food to that temperature will destroy that toxin, making the food safe for immediate consumption, or immediate refrigeration.)
See the following NIH document for further information:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10137509/
“…a minimum heat treatment of twenty minutes at 79°C or 5 min at 85°C for the inactivation of botulinum toxins…”
SAFEST METHOD
After 6 hours of baking at 200F/93C, place the pot of garlic cloves on the stovetop and, using a kitchen thermometer, hold the cloves at 185F/85C for 5 minutes.
Remove the garlic with a strainer and immediately serve, or cool in the fridge. Continue to heat the oil to 250F/121C, where any potential spores will also be killed. Then the oil can be stored at room temperature and used for any purpose.
If these cloves are used in sourdough bread (remember the cloves may still have C. botulinum spores present on them), the internal temperature of the bread will reach around 200F/93C, easily destroying any botulinin toxin that may have been produced by any spores present on the garlic within the bread dough, which can also be an anaerobic environment.
