Raspberry Transparency

Raspberry Transparency

As some of you may recall, one of my motives in creating this blog was to chronicle my experimentation with molecular gastronomy, mostly cooking bits and pieces from the beautiful Alinea cookbook. A few of my early posts, such as the one-bite caramel apple, reflected this goal.

Pectin NH, among the other chemicals

Since then, though, most of my posts have reflected more conventional ingredients. There are many reasons for this, but they mostly center around molecular gastronomy recipes taking a TON of time, being very finicky, and having results that are cool, but sort of gimmicky and repetitive. It is, after all, the sensation of an alginate sphere bursting as you bite it that's cool, not the fact that the sphere tastes of beet or ginger or apple.  That's not to say these things aren't worth playing with, just that doing so requires many free hours or a small army of sous chefs and interns. I have neither.

Straining raspberries

Occasionally, though, it's still fun to dabble. And with a little extra time this week, I decided to make Achatz's raspberry transparency once more. By Alinea standards, this is a simple recipe. Ingredient-wise it just requires some raspberries, sugar, rose water and a particular type of pectin labeled 'NH'. Equipment-wise one just needs some food-grade acetate sheets (I bought a case a couple years ago) and a dehydrator (check). Time-wise it takes a couple hours over about 2 days. Easy.

Oh, yeah, Achatz makes these with candied rose petals and sprays them with a freeze-dried yogurt powder. I don't have easy access to edible rose petals, yogurt powder or a food-safe paint sprayer, so skipped those parts.

Raspberry juice

Since the last time I had tried this one, though, I like to think that I've gotten better at pulling stuff off of acetate (trickier than it sounds), partly because I'm using better acetate (I think). So I thought I'd see how it'd work a second time.

The recipe basically involves making and then twice-dehydrating a raspberry gel. First step: make raspberry juice (when life deals you raspberries...). To do so, I cooked a pint or so (300g) of raspberries with a bit of sugar and water, mashing until they were thoroughly crushed. Then I strained it through a fine-mesh strainer in the fridge overnight.

Dehydration, Round 1

Next step: make the juice into a gel. I cooked the resulting juice with a bit (7g) of kewra water (like rose water, but better because I already had some in the kitchen) and blended with a few grams of pectin NH using an immersion blender. This mix was then cooled, allowed to gel, and then gently heated again until just liquid. As far as I can tell from some Googling, the unique trait of pectin NH is that it can gel, reheat to liquid, and gel again.

Third step: Dehydration, round 1. The gel is spread very thin on sheets of acetate, which are then dehydrated for about 4 hours at 105 F. The result of this first dehydration step is sort of a very thin, somewhat leathery fruit roll-up. These are then removed from the acetate, trying to keep them in large chunks, and placed back on the dehydrator trays for round 2: four more hours of dehydrating, this time at 125 F until they are crisp.

Dehydration, Round 2

The result is exactly what it sounds like: raspberry transparency. Very thin, crisp bits of raspberry sheets that feel and look like plastic transparencies. The taste is subtle, but the flavor of raspberry is quite evident. The texture is unique. First it feels like you're eating flavored plastic, and then it quickly dissolves on the tongue.