Sour Grapes: An Under-Appreciated Ancient Ingredient – Gardenista

Do you have a case of sour grapes? That may not a bad thing—as long as we’re talking about the fruit, and not a dose of social media-induced envy or FOMO. Bright green, shockingly tart, unripe grapes are a very interesting and very healthy ingredient, a substitute for lemon juice or lemon slices in savory dishes, and the basis of inspiring condiments like verjuice (from French verjus —”green juice”), the bracingly sour liquid pressed from green grapes, as well as cooked syrups, whose shelf lives are longer.

Photography by Marie Viljoen.

I first became aware of sour grapes’ potential—and history—when I saw them one June at Balady, a halal supermarket in the Brooklyn neighborhood of Bay Ridge, where interesting produce shows up regularly: fresh grape and mallow leaves, unripe almonds, green, unshelled chickpeas. I pounced on them, taking home one conservative bunch. This happy encounter led to much experimentation, and to real satisfaction at dinner time.

Unripe grapes as an ingredient are not new. Before lemons (native to Asia) became commonplace around the Mediterranean and Europe (where fragrantly thick-skinned but juice-less citrons had arrived in Greco-Roman times), Greeks used sour grape juice as medicine—Aristophanes mentions it in Plutus (circa 408BCE).

The juice of unripe grapes is in fact antimicrobial (as well as stunningly high in antioxidants). This I learned after a failed attempt at making a sour grape vinegar one summer in Cape Town where the green bunches were dripping from fences in Constantia, an old wine-producing area. Instead of the anticipated fizzing activity that usually begins after a few days, the mixture just sat there, sulking. Nothing happened. I did some research. Their antibacterial properties presumably worked against the beneficial microbes needed for fermentation to occur (this recalcitrance changes as sugar builds up in riper grapes).

The Romans (whose food was basically Greek in technique then) deployed defrutun, a syrupy reduction of ripe juice, liberally, and it’s likely the juice of immature grapes was appealing as a souring agent, too (although finding reliable citations that wade accurately through the murk of Latin translation is challenging). But by the Middle Ages, certainly, verjuice was a commonplace, if summer-centric ingredient. (Interestingly, it could also be made with the puckering juice of crabapples or other tart fruit, like gooseberries—sourness has always been sought-after.)

Fresh, raw verjuice does not last long without refrigeration, or without preservatives like citric acid or sulphites. It oxidizes quickly, fading rapidly from a vivid green to sepia. Commercial versions are available (if one hunts diligently for them) and usually contain sulfites for preservation, and resemble white wine in color, thanks to clarification. Just-pressed verjuice will usually turn muddy-green while you are working, but it tastes vividly fresh.