Carotenoids, tocopherols, minerals and phytate in fresh and carotenoids and tocopherol contents in sun-dried dark green leafy vegetable varieties from the Lindi region, Tanzania

Adili Bendantunguka Tiisekwa; Bernard E. Chove; Richard Mongi; Constance Rybak; Wolfgang Stuetz; Adili Bendantunguka Tiisekwa; Bernard E. Chove; Richard Mongi; Constance Rybak; Wolfgang Stuetz

doi:10.48130/tihort-0024-0011

Figures (3) Tables (6)

Figure 1.
Study areas, Nachingwea and Ruangwa districts.
Figure 2.
(a) Open sun drying (traditional drying), (b) direct solar drying, and (c) indirect solar drying.
Figure 3.
Variation of the average ambient and drying temperatures (°C) inside the dryers over time (d) in both villages for 7 d.

Botanical name	Local/English name	Origin		Conversion factor
Botanical name	Local/English name	Mitumbati	Mibure	Conversion factor
Amaranthus graecizans	Tindi pori/Amaranthus	√	−	5.27
Amaranthus maadira	Mchicha bangi/Amaranthus	√	−	4.87
Amaranthus spinosus	Mchicha pori/Amaranthus	√	√	5.78
Amaranthus spp.	Mchicha wa nyumbani/Amaranthus	√	√	6.33
Amaranthus viridis	Tindi ya nyumbani/Amaranthus	√	√	4.49
Cleome gynandra	Mgagani/African spider plant	√	−	4.60
Corchorus olitorius	LilendeJute mallow)	√	√	6.06
Curcubita maxima	Majani ya maboga/Pumpkin leaves	√	√	4.51
Dioscorea spp.	Nandelele	√	−	5.49
Gisekia pharnaceoides L.	Mtimba mwisi	√	−	5.96
Ipomea aquatica	Mkokobwado	√	√	7.48
Ipomea batatas L.	Tembele/Sweet potato leaves	√	√	5.67
Manihot esculenta	Kisamvu/Cassava leaves	√	√	2.96
Vigna unguiculata L.	Majani ya kunde/Cowpea leaves	√	√	4.90
√ means the vegetable is from the respective district while − means that the vegetable is not present in the district. Conversion factor = FW/DW, fresh weight/freeze-dried weight.

Table 1.

Fresh vegetable samples (collected 2018) names and origin.

Botanical name	lutein-zeaxanthin	α-carotene	β-carotene	RE	M	F	α-tocopherol	γ-tocopherol	α-TE	M	F
Amaranth maadira	5.14 (4.80, 5.50)^c	0.07 (0.05, 0.07)^a,b	1.08 (0.8, 1.26)^b	93	15	19	1.39 (1.30, 1.40)^a,b	0.01 (0.01, 0.01)^b	1.40	14	19
Amaranthus graecizans	10.6 (10.4, 11.1)^a,c	0.50 (0.40, 0.60)^a	6.38 (4.90, 7.40)^a,b	553	92	111	2.07 (1.80, 2.20)^a,b	0.60 (0.50, 0.60)^a,b	2.16	22	29
Amaranthus spinosus	4.90 (4.90, 5.10)^c	0.09 (0.09, 0.10)^a,b	1.47 (1.30, 1.50)^b	127	27	33	0.99 (0.90, 1.10)^b	0.01 (0.01, 0.01)^b	1.00	10	13
Amaranthus spp	6.67 (6.12, 6.94)^b,c	0.38 (0.20, 0.40)^a	4.66 (3.05, 5.50)^a,b	404	67	81	1.21 (1.0, 1.40)^a,b	0.05 (0.03, 0.05)^b	1.21	12	16
Amaranthus viridis	8.01 (6.53, 9.29)^a,c	0.38 (0.20, 0.80)^a	2.75 (2.20, 4.70)^a,b	245	41	49	1.27 (1.20, 1.40)^a,b	0.04 (0.03, 0.05)^b	1.30	13	17
Cleome gynandra	11.9 (11.5,12.0)^a,c	0.12 (0.10, 0.13)^a,b	6.89 (5.50, 9.70)^a	579	97	116	1.06 (1.00, 1.10)^a,b	0.19 (0.10, 0.20)^a,b	1.12	11	15
Corchorus olitorius	8.73 (8.20, 9.26)^a,c	0.03 (0.02, 0.05)^b	2.82 (2.20, 5.20)^a,b	236	39	47	3.20 (1.50, 5.20)^a,b	0.35 (0.2, 0.5)^a,b	3.23	32	43
Curcubita maxima	12.0 (9.58, 14.8)^a	0.21 (0.08, 0.29)^a,b	2.84 (2.20, 3.50)^a,b	245	41	49	2.78 (2.10, 3.80)^a,b	1.23 (0.90, 1.50)^a	2.92	29	39
Dioscorea spp	5.02 (4.74, 5.20)^c	0.01 (0.01, 0.02)^b	1.01 (0.90, 1.40)^b	85	14	17	0.59 (0.50, 0.70)^b	2.30 (2.10, 2.50)^a	0.83	8	11
Gisekia pharnaceoides L.	5.92 (5.70, 6.34)^b,c	0.02 (0.01, 0.02)^b	1.53 (1.40, 2.10)^a,b	128	21	26	0.43 (0.40, 0.50)^b	0.15 (0.14, 0.16)^a,b	0.44	4.4	6
Ipomea aquatica	5.40 (5.00, 6.00)^c	0.10 (0.08, 0.10)^a,b	2.80 (2.40, 4.40)^a,b	238	40	48	0.76 (0.70, 0.80)^b	0.10 (0.07, 0.10)^b	0.77	8	10
Ipomea batatas L.	7.91 (7.74, 8.07)^b,c	0.29 (0.24, 0.30)^a	4.50 (2.80, 6.90)^a,b	387	65	77	0.74 (0.60, 0.80)^b	0.08 (0.08, 0.10)^b	0.75	7	10
Manihot esculenta	20.3 (17.8, 21.4)^a	0.07 (0.05, 0.10)^a,b	6.74 (4.40, 7.70)^a	565	94	113	12.5 (8.20, 16.6)^a	1.03 (0.70, 1.10)^a	12.6	126	168
Vigna unguiculata L.	12.9 (10.9, 15.0)^a,b	0.10 (0.05, 0.30)^a,b	4.28 (3.10, 10.9)^a,b	362	60	72	1.60 (1.10, 2.00)^a,b	0.27 (0.20, 0.30)^a,b	1.63	16	22
Values are expressed as medians of four or eight determinations (extraction/analysis) for carotenoids and tocopherols; values in parenthesis represent minimum and maximum values; values within a column not sharing a common superscript letter (a,b,c) are signiﬁcantly different (p-value < 0.05); M = Males and F = Females; RE, retinol equivalents (sum of RE), for which 1 RE = 24 µg α-carotene or 12 µg β-carotene. RNI, recommended nutrient intakes for vitamin A by WHO/FAO^[24]; values (microgram) for male (600 µg RE/d) and female (500 µg RE/d) adults (19–65 years). α-TEs, α-tocopherol equivalents (1 mg α-TE = 1 mg α-tocopherol or 10 mg γ-tocopherol. RNI, recommended nutrient intakes for vitamin E by WHO/FAO; values (mg) for male (10 mg/d) and female (7.5 mg/d) adults (19–65 years).

Table 2.

Lutein-zeaxanthin, α- and β-carotene and α- and γ-tocopherol in fresh DGLVs (mg/100 g fresh weight).

Botanical name	Iron	M	F	Zinc	M	F	Calcium	M	F	Magnesium	M	F
Amaranthus maadira	2.55 (2.52,2.56)^ab	18	9	0.41 (0.41, 0.40)^b	3	4	381 (376, 393)^a,b	38	29	309 (309, 314)^a,b	119	141
Amaranthus graecizans	6.28 (6.19, 6.32)^ab	45	21	1.15 (1.14, 1.17)^a,b	8	12	393 (379, 403)^a,b	39	30	371 (371, 379)^a	143	169
Amaranthus spinosus	3.50 (3.45, 3.56)^ab	25	12	0.39 (0.39, 0.39)^b	3	4	435 (408, 456)^a	44	33	165 (165, 166)^a,b	63	75
Amaranthus spp	1.70 (1.71, 1.81)^b	12	6	0.55 (0.54, 0.57)^a,b	4	6	295 (283, 314)^a,b	30	23	115 (105, 117)^a,b	44	52
Amaranthus viridis	5.31 (5.24, 5.38)^ab	38	18	0.72 (0.71, 0.75)^a,b	5	7	469 (405, 547)^a	47	36	217 (214, 218)^a,b	84	99
Cleome gynandra	11.1 (10.6, 11.7)^a	80	38	0.65 (0.65, 0.66)^a,b	5	7	237 (236, 237)^a,b	24	18	54.0 (53.9, 54.2)^a,b	21	25
Corchorus olitorius	4.69 (1.71, 7.70)^ab	34	16	0.50 (0.49, 0.50)^a,b	4	5	235 (151, 321)^a,b	23	18	55.0 (44.5, 64.8)^b	21	25
Curcubita maxima	4.20 (3.10, 5.31)^ab	30	14	0.71 (0.70, 0.71)^a,b	5	7	232 (216, 249)^a,b	23	18	115 (106, 126)^a,b	44	53
Dioscorea spp	8.74 (8.66, 8.79)^a	62	30	0.44 (0.44, 0.44)^a,b	3	4	235 (235, 238)^a,b	24	18	278 (276, 279)^a,b	107	126
Gisekia pharnaceoides L.	5.14 (5.08, 5.25)^ab	37	18	0.51 (0.51, 0.52)^a,b	4	5	76.9 (75.3, 78.0)^b	8	6	61.2 (59.6, 62.0)^a,b	24	28
Ipomea aquatica	3.64 (3.13, 4.21)^ab	26	12	0.39 (0.23?, 0.54?)^b	2	3	115 (105, 130)^b	12	9	37.4 (33.9, 41.6)^b	14	17
Ipomea batatas L.	3.79 (3.55, 4.02)^ab	27	13	0.34 (0.29, 0.40)^b	2	3	127 (119, 136)^b	13	10	68.0 (61.1, 73.5)^a,b	26	31
Manihot esculenta	2.21 (2.11, 2.34)^b	16	8	1.41 (1.37, 1.43)^a	10	14	212 (190, 237)^a,b	21	16	94.5 (94.0, 94.9)^a,b	36	43
Vigna unguiculata L.	2.93 (2.23, 3.87)^ab	21	10	0.58 (0.54, 0.63)^a,b	4	6	208 (159, 258)^a,b	21	16	58.0 (56.8, 59.5)^b	22	26
Values are medians (minimum, maximum) of three or six determinations (extraction/analysis) or percentages (contributions for M, F); values within a column not sharing a common superscript letter (a,b) are signiﬁcantly different (Kruskal-Wallis multiple pairwise comparison; Adj. p < 0.05). M = Males and F = Females; RNI, recommended nutrient intakes by WHO/FAO^[24], values all in [mg/d] for adults by gender (19–65 years): iron (10% bioavailability) – 14 (M) and 29 (F); zinc (low availability) – 14 (M) and 9.8 (F); calcium 1,000 (M) and 1,300 (F); magnesium – 260 (M) and 220 (F).

Table 3.

Mineral contents (mg/100 g 'estimated' fresh weight) of DGLV and their contribution (%) to the daily recommended nutrient intake by gender (M, F).

Botanical name	Total phytate	Phy:Fe	Phy:Zn	Phy:Ca	Phy:Mg
Amaranth maadira	6.08 ± 0.57^b	0.20	1.47	0.00	0.00
Amaranthus graecizans	5.64 ± 0.53^b	0.08	0.49	0.00	0.00
Amaranthus spinosus	5.14 ± 0.48^b	0.12	1.31	0.00	0.00
Amaranthus spp.	4.69 ± 0.44^b	0.23	0.84	0.00	0.00
Amaranthus viridis	6.26 ± 0.63^b	0.10	0.86	0.00	0.00
Cleome gynandra	23.0 ± 1.90^a	0.17	3.50	0.01	0.02
Corchorus olitorius	13.1 ± 9.54^a,b	0.23	2.52	0.00	0.01
Curcubita maxima	9.50 ± 3.24^b	0.18	1.25	0.00	0.00
Dioscorea spp.	1.82 ± 0.16^b	0.02	0.41	0.00	0.00
Gisekia pharnaceoides L.	1.66 ± 0.15^b	0.03	0.32	0.00	0.00
Ipomea aquatic	10.1 ± 1.87^b	0.25	3.50	0.01	0.01
Ipomea batatas L.	4.88 ± 0.54^b	0.11	1.42	0.00	0.00
Manihot esculenta	9.59 ± 0.88^b	0.37	0.67	0.00	0.00
Vigna unguiculata L.	6.44 ± 0.66^b	0.19	1.10	0.00	0.00
Values are means and standard deviation of two or four determinations (extraction/analysis) for phytate; values within a column not sharing a common superscript letter (a,b) are signiﬁcantly different (p-value < 0.05). Phy = phytate, Fe = iron, Zn = zinc, Ca = calcium and Mg = magnesium; Molar masses (µ/mol) for phytate: 660.04, Fe: 55.84, Zn: 65.38, Ca: 40.07 and Mg: 24.30; Critical values of molar ratios predicting the inhibitory effect of phytate on Fe, Zn, and Ca: phytate:iron > 1, phytate:zinc > 15, phytate:calcium > 0.24.

Table 4.

Phytate content (mg/100 g fresh weight) and its ratios to individual minerals in DGLVs.

Botanical names	Lutein- zeaxanthin			α-carotene			β-carotene
Botanical names	Open sun	Direct solar	Indirect solar	Open sun	Direct solar	Indirect solar	Open sun	Direct solar	Indirect solar
Amaranthus graecizans	33.0^ab	22.58^b	38.9^a	1.04^ab	0.09^b	1.12^a	20.4^a	6.96^b	17.4^a
	(31.2, 38.2)	(22.4, 22.8)	(37.0, 42.0)	(0.89, 1.17)	(0.09, 0.19)	(0.95, 1.37)	(13.2, 23.7)	(6.89, 7.32)	(16.0, 22.9)
Amaranthus spp.	18.8^ab	21.1^a	11.4^b	1.01^a	0.38^ab	0.21^b	12.0^a	11.2^ab	4.44^b
	(18.3, 20.9)	(20.4, 22.4)	(11.1, 11.8)	(0.90, 1.10)	(0.35, 0.54)	(0.18, 0.24)	11.6, 12.6)	(10.6, 11.4)	(4.32, 4.48)
Amaranthus viridis	28.1^a	16.0^b	21.0^ab	1.90^a	0.81^b	1.20^ab	13.9^a	7.58^b	8.73^ab
	(24.8, 30.2)	(14.1, 17.3)	(17.4, 23.6)	(1.76, 2.37)	(0.75, 0.86)	(1.11, 1.32)	(12.4, 19.4)	(6.92, 8.23)	(8.26, 9.18)
Corchorus olitorius	33.3^ab	43.7	29.1^b	0.22^ab	0.49^a	0.14^b	8.81^b	27.4^a	9.83^ab
	(28.7, 34.8)	(40.6, 45.6)	(28.7, 29.3)	(0.10, 0.31)	(0.29, 0.60)	(0.10, 0.17)	(8.04, 9.07)	(20.4, 28.7)	(9.53, 10.1)
Curcubita maxima	20.2^a	24.2^a	23.0^a	0.44^a	0.76^a	0.54^a	6.04^a	7.31^a	6.93^a
	(19.0, 20.9)	(20.2, 25.3)	(15.9, 30.5)	(0.39, 0.54)	(0.52, 1.24)	(0.27, 0.64)	(5.78, 6.59)	(6.56, 7.66)	(4.81, 9.14)
Gisekia pharnaceoides L.	18.1^ab	27.2^a	16.3^b	0.63^a	0.23^ab	0.12^b	6.55^a	13.2^b	6.30^a
	(16.8, 19.0)	(25.3, 28.5)	(14.9, 17.7)	(0.18, 0.68)	(0.18, 0.30)	(0.4, 0.15)	(6.24, 7.31)	(9.26, 14.7)	(5.12, 6.99)
Ipomea aquatica	21.1^ab	24.3^a	17.2^b	0.39^ab	0.29^b	0.52^a	7.62^ab	9.11^a	5.20^b
	(20.5,22.0)	(23.7, 24.6)	(16.9, 17.4)	(0.33, 0.50)	(0.23, 0.33)	(0.37, 0.61)	(7.21, 8.05)	(8.84, 9.43)	(5.07, 5.21)
Ipomea batatas L.	28.8^a	32.1^a	26.9^a	0.74^a	0.78^a	0.59^a	14.0^a	15.6^a	11.8^a
	(20.5, 35.5)	(22.8, 35.4)	(24.1, 28.4)	(0.26, 1.23)	(0.63, 1.07)	(0.48, 0.74)	(10.7, 17.5)	(11.1, 20.3)	(10.5, 14.1)
Manihot esculenta	43.1^as	34.0^a	41.6^a	0.25^a	0.34^a	0.29^a	17.7^a	13.5^a	20.5^a
	(40.0, 40.7)	(27.5, 47.2)	(40.1, 50.4)	(0.18, 0.32)	(0.13, 0.66)	(0.22, 0.41)^a	(12.6, 23.4)	(7.6, 24.3)	(14.2, 23.8)
Vigna unguiculata L.	35.3^ab	39.3^a	31.1^b	0.62^a	0.86^a	0.67^a	12.1^a	12.0^a	9.77^a
	(23.6, 40.9)	(36.1, 41.4)	(30.4, 31.8)	(0.41, 0.99)	(0.54, 1.10)	(0.48, 0.90)^a	(1.1, 14.3)	(10.2, 15.8)	(9.13, 12.5)
Values are medians of four determinations (extraction /analysis) for lutein-zeaxanthin, α and β-carotene (n = 4). Values in parenthesis represent minimum and maximum values; values within a row not sharing a common superscript letter are signiﬁcantly different at p < 0.05 (Friedman' 2 way ANOVA, multiple pairwise comparison).

Table 5.

Lutein- zeaxanthin, α and β-carotene contents (mg/100 g dry weight) of DGLVs from different drying methods.

Botanical names	γ-tocopherol			α-tocopherol
Botanical names	Open sun	Direct solar	Indirect solar	Open sun	Direct solar	Indirect solar
Amaranthus graecizans	5.79^ab	1.29^b	6.96^a	31.8^a	2.34^b	40.4^a
	(5.43, 5.85)	(1.24, 1.34)	(6.81, 7.21)	(30.3, 33.1)	(2.28, 2.46)	(39.3, 40.7)
Amaranthus spp.	0.96^a	0.26^b	0.56^ab	12.5^a	6.24^ab	4.76^b
	(0.90, 1.01)	(0.23, 0.31)	(0.38, 0.58)	(12.0, 13.3)	(5.35, 6.92)	(4.15, 5.01)
Amaranthus viridis	1.43^a	0.28^b	1.07^ab	25.9^a	6.14^b	19.8^ab
	(1.35, 1.47)	(0.25, 0.39)	(0.94, 1.19)	(25.1, 27.7)	(5.41, 7.04)	(17.2, 22.7)
Corchorus olitorius	3.79^a	2.40^b	3.51^ab	50.6^a	22.2^b	40.8^ab
	(3.49, 4.01)	(2.20, 2.59)	(3.35, 3.64)	(47.7, 52.9)	(20.2, 24.3)	(38.6, 43.2)
Curcubita maxima	3.49^a	3.73^a	4.99^a	14.6^a	16.3^a	18.5^a
	(2.61, 4.25)	(1.40, 6.56)	(2.26, 7.65)	(12.2, 16.4)	(8.07, 24.9)	(6.36, 31.1)
Gisekia pharnaceoides L.	4.71^a	4.07^ab	3.88^b	6.68^b	28.2^a	8.47^ab
	(4.67, 4.80)	(3.95, 4.51)	(3.63, 4.12)	(6.15, 7.18)	(27.4, 32.1)	(7.55, 9.32)
Ipomea aquatica	1.15^a	0.53^b	0.64^ab	15.8^a	1.55^b	3.96^ab
	(1.10, 1.25)	(0.52, 0.58)	(0.63, 0.66)	(14.5, 18.4)	(1.42, 1.61)	(3.88, 4.09)
Ipomea batatas L.	1.25^a	0.90^a	0.74^a	24.1^a	6.73^b	6.49^b
	(1.02, 1.53)	(0.36, 1.35)	(0.52, 1.07)	(16.0, 33.8)	(1.46, 12.5)	(4.81, 9.16)
Manihot esculenta	2.57^a	2.78^a	2.35^a	25.9^a	34.5^a	32.0^a
	(1.69, 3.45)	(0.93, 4.91)	(1.62, 3.08)	(22.2, 29.2)	(18.0, 59.6)	(22.5, 37.5)
Vigna unguiculata L.	1.67^a	5.03^a	1.24^a	10.8^a	19.9^a	12.0^a
	(1.21, 2.74)	(0.72, 10.3)	(1.16, 6.41)	(10.4, 14.4)	(7.51, 34.9)	(8.60, 15.6)
Values are medians of four determinations (extraction/analysis) for α and γ-tocopherol; values in parenthesis represent minimum and maximum values; values within a row not sharing a common superscript letter are signiﬁcantly different (p-value < 0.05).

Table 6.

α and γ- tocopherol contents (mg/100 g dry weight) of DGLVs by different drying methods.