Sunday, April 22, 2012

Droppin' knowledge on homemade dressings

Howie and I love food. We LOVE food. If you met me in high school, you wouldn't think I could possess a domestic side. I hated indoor chores, I hated outdoor chores, I didn't cook (my mom was a stay-at-home-mom and did all of the cooking), and I could only bake goods that came in a box (still my preferred method for brownies: holla Ghirardelli). However, once we became juniors in college, we graduated to the apartment life. Goodbye food plan, hello kitchen. Howie's upbringing was totally different. Both his parents worked so he had to learn to cook and get along on his own. At one point during the beginning of our junior year, Howie decided to make me a dinner. I was shocked and impressed. He seemed to have so much fun doing it and just whipped it up from memory. He taught me some of his tricks and I began watching the food network religiously. I love cooking, finding new recipes, and I've even started coming up with my own. Howie also has his repertoire so we split the cooking responsibilities about 60/40 depending on who is the most stressed  with school. 

Which brings me to the point of this post. Howie recently made a delicious meal which included a salad and lime-cilantro vinegarette. The recipe he used for the dressing made a large amount, so I saved it as left overs. If you know me, you know I'm not super germaphobic and I usually go by my nose when deciding if something is still good. This dressing I knew was super acidic (lots of lime juice and lots of vinegar) so I figured it would last awhile. Recently, I decided to make myself dinner with left over chicken and I decide to use the dressing to make a salad. Its been over a week now since it was originally made, but it still looks and smells good. So I'm chugging along and I'm wondering how long do homemade dressings actually last? To Google I went. 

Now, I would never claim to be any sort of advanced or even experienced cook. But I was in for a real surprise that definitely brought me back down to a feeling of "novice" status. I found this great post that asked the question "How long do home made dressings keep in the fridge." The first response explained very well how different ingredients in the homemade dressing make for different shelf lives. This made sense. The part that caught my attention was this one little sentence, however: 
"The classic is the homemade garlic oil: you can keep pure garlic and pure oil for months in the pantry, but once you combine them, you get a botulism risk."
At first I just re-read it and tried to wrack my brain to see if I could figure out what this meant. I've seen on the food network that some of the chefs make garlic infused oil and that it is a popular commodity among Italians. I also knew garlic was one component of this dressing, in addition to the oil. So I typed in a new search: "Garlic in Oil." As I read through a couple of the hits I became more and more nervous. Keep in mind, I'm still eating and am already about half way finished with my salad. Apparently, garlic in oil stored at room temperature is a breeding ground for the bacteria Clostridium botulinum, the bacteria that causes botulism. Botulism is a scary, progressive, and often deadly reaction to the botulinum toxin released by these bacteria. The toxin is a paralytic and in high enough concentrations gradually paralyzes the muscles of the victim eventually leading to paralysis of the muscles that keep you breathing. It may start with abdominal cramping, fatigue, droopy eyes, and weakness in the arms and legs. Over time symptoms progress, reflexes are lost, and if the diagnosis is not made, it becomes deadly. The problem is, its a hard diagnosis to make. In this day and age, botulism is uncommon enough that it is probably not at the top of a doc's list and the initial symptoms can mimic a variety of diseases. Once this diagnosis is correctly made, anti-toxin is given.

So, as I'm reading these articles about the risks of garlic in oil, I'm becoming increasingly nervous. I start researching botulism itself (like I said, its not a common condition and its not the top culprit of food poisoning). Symptoms may come on in 18-36 hours. I promptly tell Howie if I start acting weird and become weak, bring me to the ER and tell them to look for botulism. He thinks I'm crazy. And then the rationalization starts. Well, its not garlic alone in oil. Its got lots of acid to kill bacteria, and it was kept in the fridge. So, that's okay, right? As you can tell, I'm still living today so clearly I did not get botulism. But its an important point to take home since homemade dressings are delicious - once you start making them, you'll want to make more. Here are the tidbits I found out during my research. {I apologize for not remember what sources I got this stuff from to properly give them credit, but the general tips are ones I found repeated in several of the sites I visited}

1. Clostridium botulinum is a bacteria often found in dirt. Its spores can adhere to any vegetables grown in the ground, such as garlic. Botulism is often associated with canned vegetables. This type of bacteria can only grow in an environment without oxygen (something called anaerobic). Once ground vegetables are sealed into a liquid with no oxygen available and are not properly preserved, the spores "hatch" to life and the bacteria begin growing and producing toxin.

2. Don't ever store garlic in oil at room temperature, EVER. The oil seals in the bacteria and seals out the oxygen.

3. Some sites say garlic in oil stored in the fridge can last up to 7 days max. Attempt at your own risk.

4. There are a few ways to reduce risk if you want to store it, such as drying out your garlic completely before infusing it into the oil, or heating it up to a specific temperature for a specific amount of time before putting it in the oil, or pickling it in vinegar, or acidifying the concoction. None of these are sure-fire ways of eliminating all bacteria and their spores (the dormant form that only starts growing in the right conditions). My dressing contained large amounts of vinegar and lime juice, which is probably what made it safe enough.

5. Likewise, some sites say that it can be stored in the freezer to keep for longer.

6. VERY IMPORTANT: There is no way to tell if your dressing or garlic oil has gone bad because this bacteria and its toxins are colorless and odorless! 

So, best way to avoid the risk: make a small quantity of dressing you can finish fresh that day or that you will only have a small amount leftover to finish in the next couple of days.Always store it in the fridge, never on the counter. Based on the information I read, I would highly recommend against keeping any homemade dressing containing garlic and oil for more than one week, regardless of the other ingredients. Most importantly, if you don't make homemade dressings yet, don't be afraid to. They are 100% better than store bought dressing and I plan to continue testing them out. Note: everything I had to say was about STORING the dressing. Eating it fresh is absolutely safe!

For more information about botulism in general, the CDC has a great variety of information. Click here to go to their page on botulism. 


  1. Totally shared this with my family!

  2. i interpret your post to read: NEVER eat leftover homemade dressing.