Homemade basil oil: can I freeze it?

[memesuze]

I pruned my basils last night and made basil oil, ala Jerry Traunfeld, by blanching the 3 cups/3ounces of leaves briefly in salted water, squeezing dry, blending with 1.5 cups olive oil for a few minutes and then letting drain without disturbing through my yogurt cheese maker. IIRC, I've successfully frozen basil pesto that didn't have the parmesan included.

Since I generally cook just for myself, I'm not sure that I'll go through the resulting 1+ cups of basil oil before my month of refrigerator storage suggested by JT is up. Any impediments to freezing in small quantities for doling out later?

[Bicycle Lee]

I wouldn't freeze it...the flavors that are extracted from the basil, as well as the chlorophyll, would probably not react well to freezing (what happens to basil leaves when you freeze them?). Refrigerating infused oils helps keep them bright and flavorful...

HTH

edit: I suggest just giving some out to friends, or something of the like....

Edited May 27, 2004 by Bicycle Lee (log)

[sabg]

i have frozen pesto with the cheese added and not had a problem....should i leave the cheese out?

[culinary bear]

Yes... in my experience I've had no problems whatseoever freezing herb oils.

The salient point is that the more solid matter you reomve from the oil, the better it will keep.

In an ideal world (one which I don't myself inhabit) herb oils should be made daily or every two days; this is achievable in the restaurant but not at home. Freezing is a better long-term option if you want to keep beyond 5-7days (which is how long it would normaly last in the refrigerator).

As to cheese... cheese suffers badly from being frozen, as the water strata which run through a cheese freeze (and expand) and thaw, they force apart the grains of the cheese, leading to crumbly fractured cheese. Try freezing an ounce cube of cream cheese for an extreme and obvious example of this. Although harder cheese with a lower water content would suffer less from being frozen, I still wouldn't recommend it (which is why most pesto recipes ask you to abstain from putting in the parmesan if you're planning to freeze it).

Chlorophyll itself is not structurally altered by the freezing process. I was a biochemist before I was a chef, to take my word on that. :)

Good luck with the freezing - probably the biggest help would be to ~very~ finely strain the oill so as to minimise solids content as much as possible.

[fifi]

I freeze pesto all the time. Usually I leave the parmesan out. You have to be careful about herb and garlic oils. You can create a botulism problem so I have heard. Yes, the ingredients for bot are there... low acid, stuff from the garden (dirt), and no oxygen. I don't know that I have ever heard of a case, but it does give me pause and I always freeze. (ex-food microbiologist here)

A word of caution on freezing though. My sister and I learned the hard way that you should freeze your herb based goodies in glass jars with metal lids. I use the short wide mouth half cup size canning jars. Even at freezer temperatures, it is easy enough to spoon out what you want. Otherwise, the odors can permeate the entire freezer. Dill flavored ice cream is NOT a culinary fusion treat.

[culinary bear]

As long as the herbs are blanched thoroughly in boiling water (as they should be to fix the colour for a herb oil) then the risk of C. botulinum should be very low; lower at least than using the same herb raw on your salad, as long as common sense prevails and the oil is handled sensibly, not left hanging around too long at ambient temperature,etc.

I agrew with you, in that I should think that C. botulinum would proliferate far more readily in a refrigerator, which is where most people would tend to store their herb oils (or god forbid, at room temperature) than in a freezer.

Basil ice cream does go very well with strawberries, I find, although unintentional basil ice-cream does not, as you say, constitute a thing of joy. :)

[fifi]

As long as the herbs are blanched thoroughly in boiling water (as they should be to fix the colour for a herb oil) then the risk of C. botulinum should be very low; lower at least than using the same herb raw on your salad, as long as common sense prevails and the oil is handled sensibly, not left hanging around too long at ambient temperature,etc.

Nope. Blanching won't do it. I don't mean to get argumentative but that would be a dangerous assumption. The bot hangs around in the form of spores. They are the devil to kill off, think a minimum of 15 minutes in a steam autoclave running at 15 pounds. (Is that 250F? I forget.) You don't get it from salad because you don't have the environment for the spores to "sprout", grow and form the toxin. Those are the low acid anaerobic conditions you have to worry about. Botulism just kind of spooks me. I worked at FDA many years ago and had the um... opportunity to investigate a few cases. These were almost always from a home canning scenario gone wrong. We used to get "immunization" shots every 6 months but nobody really knew if the stuff worked so we were still creeped out whenever anything came into the lab for analysis.

The good news is that heat, as in thorough cooking, destroys the toxin. That is probably why it doesn't come up as often as it does what with a lot of folks doing infused oils and such. Leave it out and put it on a salad? Nope. Not me. When I make it, it goes right into the freezer.

[culinary bear]

15psi raises the boiling point to 121C, which is *engages brain*

*burning noise*

249.8F

good guess. :)

of course blanching won't kill sporulating anerobes, but we're talking safe practise here, not an industrial-quality risk assessent.

I realise it's an important poersonal thing in your experience but the risks themselves are very low in this scenario.

Besides, we're getting away from the point of the original question, which we both agree on, so no argument exists. :)

[Michael Laiskonis]

I've long been under the impression that freezing herb purees (processed either with oil or, say, a sugar syrup) further breaks down the cellulose, releasing more chlorophyll, and therefore results in a 'greener' color. Have I been mislead?

[fifi]

I've long been under the impression that freezing herb purees (processed either with oil or, say, a sugar syrup) further breaks down the cellulose, releasing more chlorophyll, and therefore results in a 'greener' color. Have I been mislead?

Probably not. It makes sense to me but I can't say that I have noticed any really big difference. But then, most of my experience is with basil pesto. Is greener a bad thing?

[Michael Laiskonis]

Green is good. I also add a pinch of ascorbic acid, or vitamin C, to preserve color.

[HKDave]

For years now, I've been preserving basil by chopping it up (fresh, unblanched), mixing it with olive oil, and freezing it. The basil darkens somwhat, but I've never had any other trouble, and after thawing I often use it uncooked such as on insalata caprese.

Your mileage may vary.

[memesuze]

The insalata caprese was the carrier for my basil oil several times this weekend, and last night

[Bicycle Lee]

I've long been under the impression that freezing herb purees (processed either with oil or, say, a sugar syrup) further breaks down the cellulose, releasing more chlorophyll, and therefore results in a 'greener' color. Have I been mislead?

I have found that when more of the chlorophyll is released and comes in contact with air, it turns "greener" but in a bad way...also, the chlorophyll has a distinct, metallic smell and taste which I find unpleasant.

edit: by "greener" in a bad way, I mean the color of salad greens that have sat in the bag too long and look like pond scum.

Edited June 2, 2004 by Bicycle Lee (log)