## 2 Materials and Methods  
### Chemicals, Plant Material, Processing, and Storage Studies  
CGA, neo-CGA, crypto-CGA, ferulic acid (FA), _p_-coumaric acid (_p_-CA), 3,5-dicaffeoylquinic acid (3,5-diCQA), methanol (HPLC grade), water (HPLC grade), orthophosphoric acid, and formic acid were purchased from Sigma Chemical Co. (St. Louis, MO, USA). White potatoes (_S. tuberosum_ L.) were obtained from a local market (HEB, Monterrey, N.L. Mexico), sorted, washed, and disinfected with chlorinated water (200 ppm, pH 6.5). Pie-cuts were obtained by cutting the potatoes into slices (thickness \(\sim\)3 mm), and each slice was then cut into four pieces, making two perpendicular cuts. Potatoes were cut using a commercial knife. Whole potatoes were used as the control. Pie-cuts were selected based on a previous study, where the accumulation of phenolics was evaluated on potatoes subjected to different cutting styles (whole potatoes, slices, pie-cuts, and shreds) and stored at 10 \({}^{\circ}\)C, where it was reported that pie-cuts stored for 96 h showed the highest accumulation of phenolics [8].  
To study the effects of temperature and storage time on the accumulation of individual phenolics, whole and pie-cut potatoes (\(\sim\)200 g) were placed in plastic containers with a capacity of 5.7 L (Sterilite, Townsend, MA, USA) and stored in an incubator (VWR, Radnor, PA, USA) for 168 h at 10\({}^{\circ}\) and 20 \({}^{\circ}\)C. Samples were collected at 96, 120, 144, and 168 h. Sampling time started at 96 h of storage, based on a previous study that reported the highest accumulation of CGA isomers at 96 h of storage when the tissue was stored at 10 \({}^{\circ}\)C [8]. Containers were ventilated every 12 h to maintain CO\({}_{2}\) accumulation below 0.15% in the headspace and avoid anaerobic metabolism in the tissue. The CO\({}_{2}\) headspace accumulation was determined with an F-950 gas analyzer (Felix Instruments, Camas, WA, USA).  
Identification and Quantification of Individual Phenolic Compounds by High-Performance Liquid Chromatography-Diode Array Detection (HPLC-DAD)  
Extraction, identification, and quantification of individual phenolic compounds in potato extracts were determined in accordance with a method previously reported by [PERSON] et al. [8]. For the extraction of phenolic compounds, potato tissue (5 g) was homogenized with methanol (20 mL) using a tissuemizer (advanced homogenizing system, VWR, Radnor, PA, USA), and then centrifuged (10,000\(\times\)\(g\), 15 min, 4 \({}^{\circ}\)C). The supernatant was microfiltered using nylon membranes (0.45 \(\upmu\)m, VWR, Radnor, PA, USA), and used as a phenolic extract.  
Thereafter, 10 \(\upmu\)L of the phenolic extract was injected to the HPLC-diode array detection (DAD) system, which was composed of a quaternary pump, an autosampler, and a DAD detector (1260 Infinity, Agilent Technologies, USA). Compounds were separated on a 4.6 mm \(\times\) 250 mm, 5 \(\upmu\)m C18 reverse phase column (Luna, Phenomenex, Torrance, CA, USA). The mobile phases consisted of water (phase A) and methanol:water (60:40, _v:v_, phase B) adjusted to pH 2.4 with orthophosphoric acid. The gradient solvent system was 0/100, 3/70, 8/50, 35/30, 40/20, 45/0, 50/0, and 60/100 (min/% phase A) at a constant flow rate of 0.8 mL/min. Chromatographic data were processed with Millenium software V3.1 (Waters Corp, Mildford, MA, USA). The identification of individual phenolics was based on their DAD spectra and elution time when compared with authentic standards and a previous report [8].  
To identify and quantify individual phenolics, calibration curves of authentic standards of CGA, neo-CGA, crypto-CGA, FA, \(p\)-CA, and 3,5-diCQA at a range of 5-250 ppm were obtained. The concentration of phenolics was expressed as the mg of each individual compound per kg of potatoes on a dry weight (DW) basis. To express the results on a DW basis, the moisture of content samples was determined by the air-oven method.