Instruments, Wilmington, DE) 5 min at 10,000 g n at 4 °C. Supernatant (3 mL) was removed to a test tube, to which 1 mL derivatizing solution, 1,2-benzenediamine dihydrochloride, was added (final Ph, 2.20–2.45), vortexed for 5 s, filtered through a 45-μm
thawed, placed in cheesecloth, and squeezed to extract the juice from the berries. Titratable acidity and pH were measured by an 877 Titrino Plus (Metrohm AG, Herisau, Switzerland) standardized to pH 2.0, 4.0, 7.0, and 10.0 buffers. Titratable acidity was
) with an automated titrimeter and electrode standardized to pH 2.0, 4.0, 7.0, and 10.0 buffers. Titratable acidity was determined using 6 g of juice diluted with 50 mL of deionized, degassed water by titration of 0.1 N sodium hydroxide to an endpoint of
Detector set at 210 nm using an X-bridge C18 column (4.6 × 250 mm, 5 μm, Waters Corporation) operated at 30 °C. The elution solvent was 0.01 mol·L −1 sulfuric acid (pH 2.6) passed at a rate of 0.5 mL·min −1 . The quantity and type of organic acids were
  =   0.8780   ×   Δ pH 3 +   1.3369   ×   Δ pH 2 +   9.9856   ×   Δ pH −   0.2569 [1] Plant growth was measured as root and shoot dry weight gain during the experiment. Root and shoot tissue from seedlings and from final replicates was oven-dried for 48 h
with the producers reporting research on nutrient solution formulations (mean = 3.1 ± 1.0) and nutrient solution pH (2.8 ± 1.0) being slightly to very beneficial ( Fig. 6 ). Additionally, with the majority of producers surveyed monitoring and
of 5 m m potassium phosphate monobasic (KH 2 PO 4 ), pH 2.65, with 0.1% of formic acid (solution A) and methanol with 0.1% of formic acid (solution B). The linear gradient of the mobile phase was programmed as follows: 5% to 15% B for 1 min, followed
was carried out on a 250 × 4.6-mm, 5-μm column (Diamonsil C18; Dikma Technologies, Foothill Ranch, CA). Detection was operated at 214-nm wavelength with 0.1 mmol·L −1 KH 2 PO 4 (pH = 2.6) as mobile phase passed through a 0.45-μm membrane filter. The
(pH 2.0, using 6 M HCl). With a separatory funnel, the free phenolic compounds were extracted with diethyl ether (5 × 20-mL portions). The extractant was composed of acetone, water, and acetic acid. The organic phase (acetone) was removed using the
20 m m potassium phosphate (pH 2.5 by phosphoric acid) at a flow rate of 1 mL/min and were detected at 210 nm. L-Proline (Sigma) dissolved in the 20 mm potassium phosphate solution was used to calibrate the standard curve. The amount of proline in