We know that citrus rind and pith are full of pectin. We also know that in the presence of calcium, an ionic bond will form, creating a thermo-irreversible gel with this pectin. At least that was our hunch. To test out our idea, we peeled a grapefruit and separated it into individual segments. We soaked the segments in a solution of water and 3% calcium gluconate for three hours. Once the citrus soaked, we rinsed it off and then soaked it in a simple syrup for a few hours to season the exterior of the grapefruit.
At this point, we started cooking. The grapefruit segments were boiled and sautéed, and they held their shape perfectly. The only change was that the interior softened, a result we were hoping for. We were even able to char the boiled segments, which we finished with lemon olive oil, smoked salt, and grains of paradise. The refinements in this process will keep us busy for a while. We need to explore soaking the grapefruit for less time to see what is the minimum amount of time needed to form a firm and delicate citrus skin. We also have plans for other citrus, from Meyer lemon to mandarin oranges. And then we need to see where else we can take this firmed-up fruit, from tempura to baked into cakes, breads, pies, and tarts.
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