Variation in the Main Health-Promoting Compounds and Antioxidant Activity of Different Edible Parts of Purple Flowering Stalks (Brassica campestris var. purpuraria) and Green Flowering Stalks (Brassica campestris var. campestris)

Abstract

Purple flowering stalks and green flowering stalks of Brassica campestris are widely cultivated in the middle and upper reaches of the Yangtze River. Here, concentrations of the main health-promoting compounds and antioxidant capacity levels were characterized in different parts (leaves, peel, flesh, and inflorescences) of purple and green flowering stalks. There were significant differences in the concentrations of health-promoting compounds between the two variants; the concentrations of pigments, especially anthocyanidins, and gluconapin, were significantly higher in purple flowering stalks than in green flowering stalks, and the progoitrin content was significantly higher in green flowering stalks than in purple flowering stalks. The leaves were judged to be the most nutritional edible part because they had the highest concentrations of pigments, ascorbic acid, proanthocyanidins, flavonoids, and total phenolics. Antioxidant capacity was also highest in the leaves, and it was positively correlated with the concentration of health-promoting compounds. Purple flowering stalks and green flowering stalks were found to be rich in health-promoting compounds, especially glucosinolates. Overall, our findings indicate that consumption of the leaves and peel would provide the most health benefits. Some suggestions are provided regarding the processing and utilization of these edible components.

Keywords: Brassica campestris; antioxidants; edible parts; glucosinolates; variant.

Figure 1

The visual appearance of purple flowering stalks and green flowering stalks (A) and their anthocyanidin (B), chlorophyll (C), and carotenoid (D) content. Same letter means no significant differences (p < 0.05) according to the LSD’s test.

Figure 2

The ascorbic acid (A), proanthocyanidin (B), flavonoid (C), and total phenolic (D) content in different edible parts of the purple and green flowering stalks. Same letter means no significant differences (p < 0.05) according to the LSD’s test.

Figure 3

Glucosinolate content in different edible parts of purple flowering stalks and green flowering stalks. (A) gluconapin; (B) progoitrin; (C) glucobrassicanapin; (D) glucoalysin; (E) glucohesperin; (F) sinigrin; (G) glucoraphanin; (H) glucoiberverin; (I) glucobrassicin; (J) 4-methoxyglucobrassicin; (K) 4-hydroxyglucobrassicin; (L) neoglucobrassicin; (M) total aliphatic glucosinolates (AGS); (N) total indolic glucosinolates (IGS); (O) total aromatic glucosinolate (RGS); (P) glucosinolates (GS). Same letter means no significant differences (p < 0.05) according to the LSD’s test.

Figure 4

The antioxidant capacity in different edible parts of the purple and green flowering stalks. Same letter means no significant differences (p < 0.05) according to the LSD’s test.

Figure 5

PCA analysis of different edible parts of purple and green flowering stalks. (A) Score plot; (B) loading plot. AGS: total aliphatic glucosinolates; IGS: total indolic glucosinolates; RGS: total aromatic glucosinolate; GS: total glucosinolates.

Figure 6

Correlation plot of the correlations between health-promoting compounds and antioxidant capacity in purple and green flowering stalks. The dashed lines between indices represent negative correlations, whereas solid lines represent positive correlations (p > 0.9). AGS: total aliphatic glucosinolates; IGS: total indolic glucosinolates; RGS: total aromatic glucosinolate; GS: total glucosinolates.