## 2 Materials and Methods
### Analytical Methods  
Dry matter content was determined as mass loss upon heating to 105 \({}^{\circ}\)C under normal pressure conditions according to PN-EN-12145:2001 [24]. The chemical composition and fiber content of the freeze-dried samples of the young shoots were determined according to AOAC methods [25]: total protein content (AOAC 950.36) was determined using Tecator Kjeltec 2200 (Tecator, Hoganas, Sweden); crude fat content (AOAC 935.38) was determined using Tecator Soxtec Avanti 2050 (Tecator, Hoganas, Sweden); ash content (AOAC 930.05) was determined using dry mineralization at 525 \({}^{\circ}\)C in a Muflon oven; dietary fiber (AOAC 930.05) was determined with a commercial Total Dietary Fiber Assay Kit (K-TDFR-100A, Megazyme International Ireland, Wicklow, Ireland) using the Tecator Fibretec System E (Tecator, Hoganas, Sweden). In short, freeze-dried samples of the young shoots were gelatinized using thermostable \(\alpha\)-amylase (E-BLAM, Megazyme International Ireland, Wicklow, Ireland). Protein and starch were removed with the addition of high purity protease (from _Bacillus licheniformis_) (E-BSPRT, Megazyme International Ireland, Wicklow, Ireland) and amyloglucidase (from _Aspergillus niger_) (E-AMGDF, Megazyme International Ireland, Wicklow, Ireland). A precipitate was formed after the addition of ethanol; the precipitate was filtered, washed in ethanol and acetone, dried, and weighed. The residue was collected and weighed. The protein content was then determined in one portion and mineralized in the other. Total dietary fiber was calculated as follows: weight of sediment minus weight of protein and ash. The digestible carbohydrate content was calculated using the following equation: digestible carbohydrate = 100 \(-\) (protein + crude fat + ash + fiber). Vitamin C content was measured and calculated as the sum of ascorbic acid and dehydro-droascorbic acid using the 2,6-dichlorophenolionophenol method (PN-A-04019:1998) [26]. At first, methanol extracts were prepared. In short, 5 g of raw vegetables were taken from an average representative sample, mixed with 80 mL of 70% methanol solution, and shaken in a water bath (Elpan 357, Lubawa, Poland) for 2 h at an ambient temperature. Next, the extracts were centrifuged (MPW-340, Warszawa, Poland), filtered, and stored at \(-\)22 \({}^{\circ}\)C [27]. On the day of the analyses, the samples were mixed with an oxalic acid solution in order to preserve the ascorbic acid against degradation, and the vitamin C content was determined using the titration of the samples with the use of 2,6-dichlorophenolionophenol in at least three repetitions. At the same time, 70% methanol extracts were used for the determination of total polyphenols according to Folin-Ciocalteu method (Sigma-Aldrich, St. Louis, MO, USA) [28]; this method was also used to test the antioxidant activity based on the ABTS** free radical scavenging ability [29]. The total polyphenol content in the extracts was measured spectrophotometrically at 760 nm (RayLeigh UV-1800 spectrophotometer, Beijing, China) and was expressed as a chlorogenic acid equivalent (CGA) (Sigma-Aldrich, St. Louis, MO, USA) in milligrams per 100 g of fresh weight on the basis of a standard curve. Antioxidant activity was measured at 734 nm (RayLeigh UV-1800 spectrophotometer) by the determination of the colored solution resulting from the reduction of ABTS** free radicals (2,2\({}^{\prime}\)-azinobis-(3-ethylbenzothiaroline-6-sulfonic acid) by the antioxidants presented in the examined product. The values obtained for each sample, after their comparison to the concentration-response curve of the standard Trolox solution, were expressed as \(\upmu\)M Trolox eq/1 g fresh weight (TEAC). The total carotenoid content was determined spectrophotometrically, according to the Polish Standard with modifications (PN-90/A-75101/12) under dark conditions to protect carotenoids from light degradation [30].