How long can I store homemade garlic-infused olive oil?
Night before last, I made an olive oil/garlic infusion. I didn't need half of it and am wondering if it is safe to store for a few days. I seem to remember something abut infused oils and bacteria. Thanks in advance.
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1.33 Tbsp of 190 proof grain alcohol
Added a mix of 3:1 Cottonseed oil/sesame oil to make 9oz (i.e a soluton with 6% alcohol)
Pre-packaged acidified minced garlic
Pre-packaged acidified minced ginger
dehydrated Chiles de arbol .
This way the oil solution is ≥6% grain alcohol by volume, AND the garlic and ginger are acidified to start with.
This by no means is something I expect to keep long term, but I feel like I can be pretty confident about this being safe for 3-5 days in the fridge.
Any thoughts or concerns?
Clostridium botulinum is a gram-positive, motile, anaerobic rod. C. botulinum produces spores which themselves produce a toxin that causes paralytic disease which may be fatal. About 145 cases per year are reported in the US.
The spores are produced by the bacteria when they are in conditions where they cannot grow. The spores are an "alternative life form" for the bacteria - a way for the bacteria to go into a dormant state that is resistant to many environmental assaults.
The spores are incredibly resistant to a large number of conditions. Viable spores have been recovered from ceramic pots that are thousands of years old. For a very interesting story about another closely related spore, Bacillus anthracis, causative agent of anthrax, do a web search for "Gruinard Island".
Spores can survive 5 hours in boiling water, but can be inactivated in 4 minutes in an autoclave which provides pressurized steam (121Â°C, 15 psi). Yes, acid and radiation affect spores and in combination can inactivate them, but the conditions required are very stringent.
I missed one very important point: Just because something smells and tastes okay does not mean it is safe! There are two classes of bacteria: Spoilage bacteria which can make food taste bad, and pathogenic bacteria which very seldom do. A single taste, just touching your tongue to food contaminated with c. botulinum can be lethal. If we could smell poisoned food, there would be very few cases of food poisoning yet 1 out of every 6 Americans become sick from their food every year.
To expand on John's post above:
Jefferson, you mention soaking ingredients in vinegar (acidification / pickling), fermentation, and cooking (Pasteurization) -- these are all accepted methods of food preparation and preservation. Mayonnaise is another example of acidification being used to prevent bacterial growth. A simple infusion of oil with garlic is potentially lethal as it creates the perfect environment for growth of clostridium botulinum, the bacterium which causes botulism.
You can read more about the danger here: http://www.fsis.usda.gov/FACTSheets/Clostridium_botulinum/index.asp
Heat is not the way to go if you want fresh garlic flavor. That's one reason why commercial preparations are acidified (see post above).
Don't let your dressing sit out > 40F for more than two hours. Time under refrigeration should be limited to no more than one week (3-5 days would be better).
You can read more about the subject here:
Some dangerous confusion here I believe.
Botulism is caused by toxins produced by the bacterium Clostridium botulinum. The poison can be deactivated by heat, typically specified as 212F for 10 minutes, but the spores of C. botulinum can survive much higher temperatures (250F) which is why pressure canning is necessary for some foods.
Garlic, like anything that comes from the ground (especially) or is exposed to airborne dirt (fruits and vegetables), can harbor botulism spores which replicate in anaerobic (oxygen poor) environments even under refrigeration which is why homemade garlic oil = bad news. Commercial flavored oils and salad dressings are properly acidified to prevent the problem (pH < 4.6).
Oils, especially those low in saturation and without added preservatives (aka anti-oxidants) should be stored away from light and under refrigeration if possible. The evil is oxidization = rancidification = free radicals = cancer. Contrary to popular belief, rancidity is a process, not an absolute condition. In other words, the nasty compounds build up gradually until, at some point, you're compelled to turn your nose away. Unfortunately it would have been more healthful to have used the oil long before then. Better to go by date than by smell.
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