Kale: An excellent source of vitamin C, pro-vitamin A, lutein and glucosinolates

Figures & data

Table 1. Total phenolic compounds, vitamin C, glucosinolates and antioxidant capacity (ORAC value) of Winterbor and Maribor kale cultivars.

Tabla 1. Compuestos fenólicos totales, vitamina C, glucosinolatos y capacidad antioxidante (valor ORAC) de los cultivares Winterbor y Maribor de kale.

	Winterbor^1,2,3	Maribor^1,2,3
Total phenolic compounds (mg/kg)	610.3 ± 18.4 a	419.8 ± 27.8 b
Vitamin C (mg/kg)	237.8 ± 25.6 b	572.6 ± 38.4 a
Total glucosinolates (µmol/kg)	318.2 ± 41.7 b	824.5 ± 139.7 a
Total antioxidant capacity (mg trolox equivalents/kg)	10513.0 ± 373.2 a	5407.7 ± 441.6 b

Notes: ¹Results are expressed in fresh weight (FW). ²Values represent the mean of tree replications ± standard error of the mean. ³Different letters in the same row indicates statistical difference by the LSD test (p <  0.05).

Notas: ¹Los resultados están expresados en base húmeda (FW). ²Los valores representan el promedio de tres repeticiones ± el error estándar del promedio. ³Diferentes letras en la misma fila indican diferencia estadísticamente significativa por la prueba LSD (p <  0.05).

Figure 1. Typical HPLC-PDA kale carotenoid and chlorophyll chromatograms (shown at 450 nm) obtained from Winterbor (A) and Maribor (B) cultivars. Tentative identification of the chromatographic peaks was performed as indicated in Table 2. Peak assignments: (1) neoxanthin, (2) violaxanthin, (3) chlorophyll b, (4) lutein, (5) chlorophyll a, (6) all-trans-β-carotene and (7) 9-cis-β-carotene.

Figura 1. Perfil cromatográfico típico obtenido mediante HPLC-PDA de carotenoides y clorofilas de kale (mostrado a 450 nm) presentes en los cultivares Winterbor (A) y Maribor (B). La identificación tentativa de los picos cromatográficos se realizó como se indica en al Tabla 2. Asignación de picos: (1) neoxantina, (2) violaxantina, (3) clorofila b, (4) luteína, (5) clorofila a, (6) all-trans-β-caroteno y (7) 9-cis-β-caroteno.

Table 2. Tentative identification of kale (Brassica oleracea Acephala group) carotenoid and chlorophyll chromatographic profiles obtained by HPLC-PDA.

Tabla 2. Identificación tentativa de los perfiles cromatográficos de carotenoides y clorofilas de kale (Brassica oleracea Acephala group) obtenidos mediante HPLC-PDA.

Peak number^1 (retention time)	λmax^2 (nm)	Tentative identification	Previously reported in kale^3	Method of identification^4
1 (11.1)	(415), 439.8, 468.8	Neoxanthin	ii, iii	B, C
2 (12.3)	(412), 436.2, 455.2	Violaxanthin	ii, iii	B, C
3 (19.6)	(315.4), 344, 466.4	Chlorophyll b	i	B, C
4 (20.9)	(422), 444.7, 473.7	Lutein	ii, iii	A, B, C
5 (25.9)	(338), (384.4), 408	Chlorophyll a	i	B, C
6 (40.5)	(430), 451.1, 478.5	All-trans-β-carotene	ii, iii	A, B, C
7 (42.1)	(420), 447.1, 473.7	9-cis-β-carotene	iii	B, C

Notes: ¹Number of peak assigned according to the order of elution from the C30 stationary phase. ²Wavelengths of maximum absorption in the UV/Vis spectra of each chromatographic peak, values in parentheses indicate a shoulder in the peak. ³Previously reported by (i) Khachik et al. (1986), (ii) Khachik et al. (1991) and (iii) de Azevedo & Rodriguez-Amaya (2004). ⁴Method applied for the identification of the peak: (A) identification by comparison with the retention time and wavelengths of maximum absorption in the UV/Vis spectra of commercial standards; (B) identification by spectral interpretation of the wavelengths of maximum absorption in the UV/Vis spectra and comparison with wavelengths of maximum absorption reported in the literature (Chandrika et al., 2005; de Azevedo & Rodriguez-Amaya, 2004; Lee et al., 2001; Mendes-Pinto et al., 2004; Taylor et al., 2006); (C) identification by the order of chromatographic elution reported in the literature (Chandrika et al., 2005; de Azevedo & Rodriguez-Amaya, 2004; Khachik et al., 1986; Lee et al., 2001; Mendes-Pinto et al., 2004; Taylor et al., 2006).

Notas: ¹Número de pico asignado de acuerdo al orden de elución de la fase estacionaria C30. ²Longitud de onda máxima de absorción en el espectro UV/Vis de cada pico cromatográfico, los valores en paréntesis indican un hombro en el pico. ³Previamente reportado por, (i) Khachik et al. (1986), (ii) Khachik et al. (1991) y (iii) de Azevedo & Rodriguez-Amaya (2004). ⁴Método aplicado para la identificación del pico: (A) identificación por comparación con el tiempo de retención y la longitud de onda máxima de absorción en el espectro UV/Vis de estándares comerciales; (B) identificación por la interpretación del espectros de absorción máxima en el espectroUV/Vis de acuerdo a reportes previos de la literatura (Chandrika et al., 2005; de Azevedo & Rodriguez-Amaya, 2004; Lee et al., 2001; Mendes-Pinto et al., 2004; Taylor et al., 2006); (C) identificación por el orden de elución reportado en la literatura (Chandrika et al., 2005; de Azevedo & Rodriguez-Amaya, 2004; Khachik et al., 1986; Lee et al., 2001; Mendes-Pinto et al., 2004; Taylor et al., 2006).

Table 3. Individual carotenoids and chlorophylls content in Winterbor and Maribor kale cultivars.

Tabla 3. Contenido de carotenoides y clorofilas individuales en los cultivares de Winterbor y Mirabor de kale.

Compound	Individual carotenoids content (mg/kg FW)^1,2,3
	Winterbor	Maribor
Neoxanthin	20.88 ± 1.26 a	5.91 ± 1.40 b
Violaxanthin	14.64 ± 0.28 a	11.26 ± 0.61 b
Chlorophyll b	100.48 ± 4.35 a	83.67 ± 2.94 b
Lutein	100.05 ± 3.83 a	71.58 ± 2.28 b
Chlorophyll a	87.85 ± 4.02 a	66.21 ± 2.47 b
All-trans-β-carotene	75.68 ± 3.57 a	68.31 ± 2.17 a
9-cis-β-carotene	12.88 ± 0.40 a	7.91 ± 0.62 b

Notes: ¹Concentrations are reported as lutein equivalents for peaks 1, 2, 3, 4 and 5; and as all-trans-β-carotene equivalents for peaks 6 and 7. All compounds were quantified at 450 nm. ²Values represent the mean of 3 replications ± standard error of the mean. ³Different letters in the same row indicate statistical difference by the LSD test (p <  0.05).

Notas: ¹Las concentraciones para los picos 1, 2, 3, 4 y 5 están reportadas como equivalentes de luteína; y para los picos 6 y 7 como equivalentes de all-trans-β-caroteno. Todos los compuestos se cuantificaron a 450 nm. ²Los valores representan el promedio de 3 repeticiones ± el error estándar del promedio. ³Diferentes letras en la misma fila indican diferencia estadísticamente significativa por la prueba LSD (p < 0.05).

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