Why We Harvested Vitalija Early

We began with a product question: when would Vitalija give us the acidity, fruit and sensory balance we wanted for verjus? The answer required more than waiting for the highest sugar reading.

This is a field note from Sarajevo Hills, based on the Vitalija 2026 · Research Case · Year Zero project record. It follows one mature pergola-grown vine through an exceptionally warm, dry growing season as described in the field record. The observations helped guide a product decision; they are not a controlled trial of a grape variety.

The intended destination was verjus

For this project, full ripeness for wine was never the sole definition of success. We wanted an early grape foundation that could carry botanicals and remain useful at the table. Verjus makes that intention possible: fruit can be picked for a particular balance before full ripeness.

Our earlier story, The Harvest Before Wine, introduces that gastronomic idea. Here we open the notebook behind it.

One pergola, several thermal environments

“Sarajevo Hills microclimate” becomes meaningful when we look inside the canopy. Sunlit leaves, shaded leaves and interior bunches did not share the same surface temperature. Handheld readings with a Fluke 62 MAX+ infrared instrument recorded the following contrasts:

On 16 August, the south-west bunches were several degrees warmer than fruit inside the pergola. The measurements establish a spatial contrast at the times observed. They do not measure berry-core temperature, continuous heat exposure or a proven rate of acid loss.

The evening readings add another dimension. At 20:30 on 13 August, leaves were recorded at 20–21°C and bunches at 23°C. By 23:18, the recorded leaf and bunch temperature was 14.5°C. A single daytime weather reading could not describe that whole experience.

The ripening notebook

These are different sample types and picking stages. They should not be plotted as if they were repeated measurements of identical berries under a fixed sampling protocol. In particular, the move from a 12 °Brix mixed sample to an 11 °Brix bulk verjus sample is not evidence that the same fruit lost sugar.

What Brix tells us — and what it leaves open

°Brix is a refractometric measure of soluble solids, commonly used to follow grape sugar development. It does not separately identify glucose and fructose, and it cannot describe aroma or the whole experience of sweetness. pH describes another aspect of the juice; it is not a substitute for titratable acidity, the acid measure usually expressed as an equivalent concentration.

The informative contrast was sensory. The 6 September bulk verjus at 11 °Brix and pH 2.8 was described as balanced and very drinkable rather than aggressively sour. At the final harvest, several tasters described the 13.5 °Brix fruit as very sweet. These were observations, not results from a blinded sensory panel. They gave us a question worth investigating: which other parts of the fruit's composition help explain its perceived balance?

Picking in stages, with different purposes

The season was not treated as one all-or-nothing harvest. An early verjus sample was recorded on 6 September; the second verjus harvest on 17 September yielded 11 kg of bunches; a final harvest followed on 27 September. The estimated seasonal total was approximately 25 kg.

That sequence matters. “Early” describes the point chosen for a particular product, relative to the later fruit. It does not mean the vine failed to ripen. The later harvest offered a different sensory experience, while the earlier juice gave the verjus project its intended direction.

Extraction was part of the experiment

The project compared a high-yield Tefal juicer with a manual Italian tomato-processing machine that separated seeds and produced a cleaner, clearer juice at a lower yield. The manual method recorded approximately 0.6 litres per kilogram. Because this was not a controlled parallel test on identical fruit, the result remains a practical observation, not a validated equipment comparison.

What the dataset can support

The ThingSpeak export contained 6,268 records from 18 August to 27 September. Field 1 was labelled as soil temperature in the project diary. Sensor depth, position, radiation exposure and calibration still need documentation before its absolute values can support physiological conclusions. For the handheld IR work, fixed measuring zones, distance, angle, emissivity and time are priorities for a repeatable protocol.

TA, separate sugars, individual organic acids and selected aroma analyses were proposed for laboratory work. They are not completed results in this field note. The 2026 study generates hypotheses from one vine; it does not establish a causal effect of heat or a general rule for Sarajevo viticulture.

From a harvest decision to a drink

At Aroma Lab, the useful outcome is a grape foundation with a clear gastronomic purpose. VITALIJA No. 01 brings that foundation together with basil and bitter citrus. Botanical Cuvées · Harvest 2026 extends it into three expressions.

Follow the wider journey in From Sarajevo Hills to Aroma Lab or take the next step at the table with the food-pairing guide.

Technical context: Iowa State University: grape sampling and maturity analysis.