*2.3. HPLC Analysis*

All standards and samples were analyzed using the Agilent 1290 Infinity Liquid Chromatography (Santa Clara, CA, USA), fitted with a quaternary pump and coupled to a UV-Vis DAD. DAD wavelengths were set to 280 nm for (+)-catechin hydrate and (−)-epicatechin; 350 nm for rutin hydrate; and 365 nm for quercetin. The eluents are 100% H2O (solvent A), 5% AcOH in H2O (solvent B) and 100% MeCN (solvent C). The HPLC method used was reported in the literature (Table S1) [33]. The standards and samples were eluted through the Phenomenex Luna C-18 Column (250 mm × 4.6 mm, 5 μm particle size, Phenomenex, Torrance, CA, USA) at a flow rate of 0.8 mL/min at 25 ◦C.

Retention times (tr) for (+)-catechin hydrate, ( −)-epicatechin, rutin hydrate and quercetin were 38.0 min, 54.5 min, 76.1 min and 94.6 min, respectively. External calibration standard curves for (+)-catechin hydrate, ( −)-epicatechin and rutin hydrate were generated, with each curve consisting of six calibration points that were measured in triplicate. Each curve displays excellent linearity with a correlation coefficient (r2) of >0.99. The limit of detection and limit of quantitation for each flavonoid per kg pomace are 13.2 mg and 43.9 mg for **1**; 1.9 mg and 6.6 mg for **2**; and 2.8 mg of rutin hydrate and 9.4 mg (of rutin) for **3**.

### *2.4. Materials and Solid–Liquid Extraction Protocol*

The solid–liquid extraction (SLE) protocol used in this study was similar to that described in the literature with some adaptations (discussed in Sections 3.1 and 3.2) [30]. Pinot noir pomace was homogenized with a kitchen blender. For the small-scale extraction study, the pomace samples (10 g) were then immersed in the solvents (50 mL) and stirred at r.t. for one hour in an open vessel. The solvent was decanted and then centrifuged at 6000 rpm for 10 min. The supernatant (5 mL) was taken, and the solvent removed in vacuo. The resulting extract was dissolved in model red wine (2 mL). This solution was passed through a Phenomenex regenerated cellulose membrane syringe filter (0.45 μm pore size, 15 mm diameter, from CA, USA) and stored at −20 ◦C until HPLC analysis. The quantities of each flavonoid in each of the samples were analyzed with HPLC according to the method described in Section 2.3. Extractions of the pomace samples with each solvent system were conducted in triplicate.

For the large-scale extraction, Pinot noir pomace (2 kg) was separated into batches (200 g). Each batch was immersed in 40:30:30 acetone:H2O:EtOH solvent (1 L) and manually stirred for 1 h. After extraction, the solid–solvent mixture was poured over a kitchen sieve to filter out the solid mass and to collect only the phenolic-enriched solvent, which was then centrifuged. For quantification, the supernatant (10 mL) from each batch was taken and combined together (total of 100 mL). The solvent was removed in vacuo. Model red wine (6 mL) was then added to the extract and separated into 3 equal portions (2 mL), which were passed through the Phenomenex syringe filter (0.45 μm pore size, 15 mm diameter, from CA, USA). The quantities of each flavonoid in each of the samples were analyzed with HPLC. The rest of the phenolic-rich solvent were combined together, and the solvent was removed in vacuo to give a resulting extract that would be used for derivatization. Various stages of this process can be seen in Figure 1.

**Figure 1.** Large-scale Pinot noir extraction procedure: (**a**) Pinot noir pomace batch (200 g) with solvent (1 L); (**b**) filtering phenolic-enriched solvent; (**c**) centrifugation of phenolic-enriched solvent; (**d**) removal of solvent from extract.

### *2.5. Derivatization of the Flavonoid-Enriched Extract and Infrared Analysis*

The starting material extract (1 g) was dissolved in dimethyl formamide (DMF, 15 mL) solvent. Triethylamine was added to this solution and then the acylating agents (octanoyl, lauroyl and palmitoyl chlorides). The reaction was stirred for 24 h and then was quenched with NaHCO3. The mixture was then filtered and washed with excess water. The resulting products were collected and dried to give red, solid products. The infrared (FT-IR) spectra of non-derivatized and derivatized products were obtained using Perkin-Elmer Spectrum 100 FT-IR spectrometer (Santa Clara, CA, USA).
