## 2 Materials and Methods
### Methods  
The determination methods were as follows: vitamin C as L-ascorbic acid content was determined according to standard methods [14]; total polyphenol content, calculated as gallic acid, was determined according to the Folin-Ciocalteu method [15] (determination of total polyphenol content was performed in methanol extracts (80% \(\%\)/\(v\) ratio of material to extraction reagent, 1:5)); and determination of chlorophyll and carotenoid content was performed according to the method described by [PERSON] et al. [16], in which the chlorophyll and carotenoid content is calorimetrically determined by measuring absorbance at the absorbance maximum for these pigments using a Shimadzu UV-160A spectrophotometer.  
The ABTS antioxidant assay was performed according to the method determined by [PERSON] et al. [17], using a Shimadzu UV-2401 PC spectrophotometer (Kyoto, Japan). All determinations were performed in triplicate.  
The DPPH radical-scavenging activity of white cabbage was determined according to the method of [PERSON] and [PERSON] [18]. To each 0.5 mL supernatant, 0.5 mL of DPPH and 1.5 mL of ethanol was added. The mixture was shaken and left at room temperature for 10 min. The antioxidant capacity of each sample was measured separately by recording the absorbance at 517 nm in a spectrophotometer (Shimadzu UV-2401 PC). Ethanol was used as a blank. All determinations were performed in triplicate.  
The analysis of organic acids was performed via high-performance liquid chromatography (HPLC), with 0.001 N sulfuric acid in isocratic mode, at 210 nm wavelength and with flow rate of 0.6 mL-min\({}^{-1}\)[19]. The assay was performed using a Dionex liquid chromatograph (USA), adapted to an UltiMate 3000 detector with diode array. The detector was connected to an LPG-3400A pump, an EWPS-3000 SI autosampler, a TCC-3000 SD column thermostat, and the Chromeleon v.6.8 computer software. Separation was carried out on an Aminex HPX-87H column (300 \(\times\) 7.8 mm) with a Bio-Red IG Cation H pre-column (30 \(\times\) 4.6), at 65 \({}^{\circ}\)C. Determination of acids using HPLC required the following sample preparation: vegetable (10 g) was diluted to 50 mL with bidistilled water and clarified by centrifugation at 6000\(\times\)\(g\) for 15 min. The extract was filtered through a 0.45 \(\upmu\)m Millipore filter and a 20 \(\upmu\)L sample was used for HPLC analysis of organic acid content.  
Shredded samples were used for the determination of amino acid content. Analysis was carried out according to the protocols specified by the manufacturer of the amino acid analyzer. The amino acid composition was determined by ion-exchange chromatography after 24 h of hydrolysis with 6 N HCl at 110 \({}^{\circ}\)C. After cooling, filtering, and washing, the hydrolytic was evaporated in a vacuum evaporator at temperatures below 50 \({}^{\circ}\)C. The dry residue was dissolved in a buffer of pH 2.2. The prepared sample was analyzed via the ninhydrin method [20]. Buffers of pH 2.6, 3.0, 4.25, and 7.9 were applied. The ninhydrin solution was buffered at pH 5.5. The hydrolyzed amino acids were determined using an AAA-400 amino acid analyzer, supplied by INGOS, Czech Republic. A photometer, working with two wavelengths (440 and 570 nm), was used as the detector. The procedure also involved use of a 350 \(\times\) 3.7 mm column packed with the ion exchanger Ostion LG ANB (INGOS), with column temperature maintained at 60-74 \({}^{\circ}\)C and detector temperature at 121 \({}^{\circ}\)C. Calculations were carried out according to the external standard. No analysis concerning tryptophan was conducted.  
Statistical analysis was performed using one-way analysis of variance (ANOVA). Differences were evaluated using [PERSON]'s test at significance level \(p\) < 0.05. All statistical calculations were performed using the computer software Statistica v.8.1. All analyses were performed in triplicate. Results are given per fresh weight of cabbage.