I don't remember when I first began preserving leaves with glycerin. As a gardener, it was just something that I did to prolong the fleeting life of flowers and foliage.
I do remember introducing it to my boys when they were young. In the autumn, we would gather branches of oak, beech, and maple leaves just as the colors began to turn and submerge them in vases filled with a solution of equal parts of water and glycerin. Over the next week, we would watch the color metamorphose as the chlorophyll ceased production, triggering the release of pigments. The glycerin, an emollient, would fill the cells, rendering the leaves supple and leathery. They would last for years this way, more so if pressed. Undoubtably, I still have some hidden between the pages of old books.
Last week, as I was preserving some blue holly cuttings this way, it occurred to me that I've only applied this procedure for decorative purposes, when all along, I've ignored its role as a food preservative. It was time to rectify that.
Within three days, a few sprigs of parsley were visibly transformed by the glycerine. The color darkened and the leaves appeared denser and heavier. The taste is sweet up front, which is surprising in a pleasant way, followed by the fresh flavor of parsley. Even after a week of sitting on the counter, loosely wrapped, the leaves are still supple and appear fresh.
Now, the obvious question arises: How can this make food better? Is the answer in its ability to preserve… or transform…or both?
Playing with Fire and Water 
Quite interesting. Glycerin is important for me because of its use in the manufacture of pharmaceuticals. I don’t think about it for food because its primary industrial application is in baking and candy production (I don’t bake or make candy) and I don’t buy a lot of extracts.
Did you find that the slightly sweet undertaste interfered at all with your bass application? What about the texture of the parsley?
I’m not sure where you could/would take this outside of herbs and leafy greens but I will be sitting here waiting to find out. I suspect that lettuce would come out with an interesting texture. Pretty sure it wouldn’t work with tomatoes (and the like) and not sure if hard vegetables (e.g. roots) would be worthwhile doing. Celery could be funky since that’s the one vegetable that sucks in whatever it is that it’s exposed to (I once served blue celery with bloody Caesars).
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Very interesting. What form of glycerin are you using, liquid? Is the ratio 1:1?
The texture you describe is very intriguing. Could you possibly preserve larger greens and use them as wraps? It seems the texture is pliable yet toughened, and of course while retaining an amazing color. Is this correct?
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Interesting! So I wonder – would this also act as a preservant after chopping the leaves? Some while ago I made an attempt at marshmallows with parsley (and banana). I discovered that the chopped parsley quickly aquired a grassy/hay like aroma – not very pleasing. In the end I simply had to go with coarsly chopped parsley. Perhaps the viscosity of the glycerol would keep cell intact and limit the access to oxygen? It’s just speculation of course, but could be worth a try.
For those interessed in the marshmallow recipe and what was tried to avoid the grassy/hay like aroma:
http://blog.khymos.org/2007/05/20/banana-marshmallows-with-parsley-tgrwt-2/
http://blog.khymos.org/2007/06/23/banana-marshmallows-with-parsley-v-15/
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Linda – this is fascinating. I am obsessed with trying to preserve basil leaves as fresh basil has such a short life – I wonder if this would work long term with Basil.
I often find that I’d like a little strong hit of Basil to go with some fish or something that I’ve cooked. I was considering making Basil oil but maybe this could be the “solution”?
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The sweetness in the small amount of parsley did not interfere with the bass. The texture is like compressed parsley.
You may be surprised by some of the applications for preserving food with glycerine that I have uncovered…everything from carrots to fish!
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yes, I use liquid glycerine with an equal amount of water.
I see no reason why larger leaves cannot be preserved in this way. When I get around to experimenting more, I’ll let you know.
In the past, I have found that with foliage that is actively producing chlorophyll, the green color remains vibrant. With autumn leaves, the best results were with those that produced yellow pigments (xanthophylls). Those that produced orange pigments (carotenoids) would eventually lose their vibrancy, turning russet. Those with red pigments (anthocyanins) would invariably turn brown.
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I haven’t tried chopping the leaves, there are so many routes to explore here. For instance, how will a product that has been treated with glycerin interact with other ingredients? Will a puree of a product that is infused with glycerin form an emulsion when processed with a fat? Or, can meat be treated with glycerin and how will it affect flavor and texture?
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I am also anxious to see if it will prevent browning in basil. I’ll keep you posted
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If the parsley was preserved this way and then you chopped it would you have the same chemical enzyme reaction that causes oxidation? Would you have to blanch it first after preserving to deactivate the enzyme? Would the preserving effect the high level of vitamin C in the parsley?
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all good questions…I don’t have any answers.
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