Grape: From Bunch to Seed

First, it's a table fruit: a bunch, berries bursting with juice, a thin skin, and at its heart, two to four seeds that we spit out without a second thought. Yet, these are what cosmetics use. Cold-pressed, these seeds yield a light, dry-to-the-touch fluid, rich in linoleic acid—and the accompanying polyphenols make it one of the most studied plant products.

• Seeds weigh almost nothing in the bunch, but they concentrate most of the fruit's polyphenols: proanthocyanidins, or OPCs.
• Pressing yields 10 to 16% of their weight in fatty matter, from the pomace left after harvest: a recovered co-product, never a dedicated crop.
• Its lipid signature: 60 to 75% linoleic acid, a dry feel, rapid absorption. Hence its use as the last step in the evening, 2 to 3 drops.
• It is fragile: once the bottle is opened, count on 6 to 9 months away from light.

Botanically, a grape is the fruit of the vine: a bunch carried by a stem, and berries—which botanists call 'baies'—composed of a skin, pulp, and seeds. The berry is essentially made of water, about 81g per 100g, and about fifteen grams of sugars (Ciqual, ANSES composition table). The pulp quenches thirst; the skin provides color and aromas; the seed, however, is not eaten—and it is precisely the only part that cosmetics retain.

The cultivated species, Vitis vinifera, was domesticated between the Caucasus and Central Asia before spreading to Mediterranean Europe. Its American cousin, Vitis labrusca, produces grapes with a "foxy" taste, rare on our stalls. In France, two uses are distinguished that have almost nothing in common: wine grape varieties, destined for wine, and table varieties, selected for berry size, skin fineness, and transport durability.

Table grapes appear in the fruit and vegetable section at the end of summer and remain on display until the first cold snaps. White, black, red, or rosé, they are chosen at a glance: a flexible green stem, well-attached berries, a light waxy bloom—the pruina—a sign that they haven't been handled too much. In the markets of Paris, Lyon, or Toulouse, the season starts with early white grapes and ends, in autumn, with large late-season berries. Once home, the bunch can be kept for about five days in the refrigerator's crisper drawer, to be consumed half an hour after being served on a fruit platter. Dried, the same fruit becomes raisins; pressed and fermented, it becomes wine—and it is wines that, indirectly, supply cosmetics.

No one cultivates vines for their seeds. The oil comes from a residue: after pressing, the marc — skins, stems, seeds — leaves the cellar by the ton. The seeds are separated, washed, dried to a low moisture content, then sorted. They contain 10 to 16% of their weight in fatty substances, which explains the volume of material needed to fill a 30 ml bottle. In terms of resources, it is one of the few cosmetic raw materials that does not require any additional agricultural land.

Then there's the extraction method. Two methods coexist, and they do not yield the same result.

Two families of molecules coexist in a seed, and they are not recovered in the same way. The fatty fraction, obtained by pressing, is dominated by linoleic acid — 60 to 75% of fatty acids depending on origin and vintage — accompanied by oleic acid, some palmitic acid, and tocopherols, the natural form of vitamin E. It is this highly unsaturated profile that gives it its dry touch and rapid absorption, but also its sensitivity to oxidation.

The polyphenolic fraction, on the other hand, is obtained by aqueous or hydro-glycerinated extraction: these are oligomeric proanthocyanidins (OPCs), of which the seed concentrates a very large part of the berry's phenolic compounds. Their antioxidant power has been measured in the laboratory since the 1990s; it is for this reason that this extract often appears in a formula, alongside a radiance active ingredient like vitamin C. As for resveratrol, it is mainly found in the skin of the berry and in the leaves, not in the seed: two molecules from the same plant, two different locations.

Sources: Garavaglia J., Markoski M. M., Oliveira A., Marcadenti A., “Grape Seed Oil Compounds: Biological and Chemical Actions for Health”, Nutrition and Metabolic Insights, 2016 · Shi J., Yu J., Pohorly J. E., Kakuda Y., “Polyphenolics in Grape Seeds — Biochemistry and Functionality”, Journal of Medicinal Food, 2003 · Ciqual nutritional composition table, ANSES.

Such a fine texture is judged over time, not on a single application. Here's the rhythm we recommend for gradually incorporating it.

• Days 1 to 14 — 2 drops, every other evening, on still damp skin. 2 minutes of massage, from the center towards the temples. Observe tolerance, nothing else.
• Days 15 to 42 — 3 drops, every evening, as the last step after cream. 60 seconds of flat pressing, without rubbing.
• Days 43 to 56 — continue in the evening and add 1 drop mixed with day cream, only if everything remains comfortable.
• The benchmark — a photo upon waking on D0 and D56, same angle, same daylight, without makeup. This is the only honest judge.

Discontinue if persistent tingling occurs, and postpone by one week after intense exfoliation.

Grapes should be kept cool; the bottle should not. An opened bottle should be stored upright in a dry, dark cupboard, with the cap tightly closed, and used within 6 to 9 months. A smell that turns cardboard-like or like varnish indicates oxidation: do not apply it. As with any new fatty substance, a patch test on the crook of the elbow 24 hours before the first application remains the simplest precaution.

Finally, a useful clarification: the fruit of the vine has nothing to do with bearberry, the common name for uva-ursi, nor with fox grape — baneberry, a toxic undergrowth plant. Three plants, three uses, and only one ends up in a skincare bottle.