In brief
Measurements that connect cultivation treatments to plant chemistry, volatile compounds, soluble solids, acidity, colour and texture.
Measurement chain
| Outcome | Preferred method | interpretation |
|---|---|---|
| Volatile profile | HS-SPME GC–MS with internal standard and batch QC | chemical abundance is not identical to perceived aroma |
| Phenolics/target metabolites | validated HPLC/LC method | target list and extraction recovery reported |
| Mineral composition | ICP-OES/ICP-MS or validated equivalent | dry/fresh mass basis stated |
| Soluble solids | refractometry, °Brix | not universally equal to perceived sweetness |
| Titratable acidity | standardised titration | more informative than tissue pH alone for acid load |
| Colour | calibrated L*a*b* imaging or colorimetry | illumination and calibration controlled |
| Texture | instrumental compression/puncture plus sensory descriptor | method geometry and speed reported |
| Fresh/dry mass | traceable balance and drying method | concentration and total amount both reported |
Instrumental colour may be reported in CIE L*a*b* coordinates when acquisition, illuminant, observer, instrument geometry and calibration are fixed.
Sampling control
Plant position, leaf age, time of day, harvest-to-analysis delay, storage temperature and sample preparation are standardised. Lettuce research shows that nutrient solution, season and post-harvest handling can alter quality and shelf-life interpretation.
Reporting concentration correctly
A treatment may increase a compound per gram while reducing total biomass. Report both concentration and total content per plant where feasible.