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Published in final edited form as: Food Chem. 2016 Feb 4;202:189–198. doi: 10.1016/j.foodchem.2016.01.135

Vitamin C and reducing sugars in the world collection of Capsicum baccatum L. genotypes

Venu Perla a, Padma Nimmakayala a,✉, Marjan Nadimi a, Suresh Alaparthi a, Gerald R Hankins a, Andreas W Ebert b, Umesh K Reddy a
PMCID: PMC4911803  NIHMSID: NIHMS792647  PMID: 26920284

Abstract

This study aimed to analyze 123 genotypes of Capsicum baccatum L. originating from 22 countries, at two stages of fruit development, for vitamin C content and its relationship with reducing sugars in fruit pericarp. Among the parametric population, vitamin C and reducing sugar concentrations ranged between 2.54 to 50.44 and 41–700 mg g−1 DW of pericarp, respectively. Overall, 14 genotypes accumulated 50–500% of the RDA of vitamin C in each 2 g of fruit pericarp on a dry weight basis. Compared with ripened fruits, matured (unripened) fruits contained higher vitamin C and lower reducing sugars. About 44% variation in the vitamin C content could be ascribed to levels of reducing sugars. For the first time, this study provides comprehensive data on vitamin C in the world collection of C. baccatum genotypes that could serve as a key resource for food research in future.

Keywords: Capsicum baccatum L., Ascorbic acid, Vitamin C, Germplasm, Fruit development, Reducing sugars

1. Introduction

l-ascorbic acid, otherwise known as vitamin C, is commonly in fruits and vegetables. The importance of vitamin C in human health has been reviewed elsewhere (Naidu, 2003; Wahyuni, Ballester, Sudarmonowati, Bino, & Bovy, 2013). Vitamin C is known to have a key role in the maintenance of collagen, a major body structural protein (Levin, 1986), wound repair and healing process (Naidu, 2003; Shukla, 1969), synthesis of muscle carnitine, which is important for fatty acid transport and energy production (Hulse, Ellis, & Henderson, 1978), dietary absorption of iron (Hallberg, 1981), and prevention or relief from the common cold (Pauling, 1970). Although inconclusive, the role of vitamin C in reduced risk of cardiovascular disease and certain cancers cannot be ignored (Naidu, 2003). It has been shown in vitro that the effects of low dose pesticides on cell viability and reactive oxygen species production can be minimized by quantities of vitamin C equivalent to the recommended daily allowance (RDA) (Perla, Perrin, & Greenlee, 2008). The RDA for vitamin C, set by the US Food and Nutrition Board, for adult men is 90 mg/day and for adult women is 75 mg/day. However, the tolerable Upper intake Level (UL) of vitamin C for adults is 2 g/day (US Food and Nutrition Board, 2000).

The amount of vitamin C available in vegetables for human consumption varies widely. In one study, red and green chilli (Capsicum annum var. longum), kale (Brassica oleracea L. var. alboglabra L. H. Bailey), and red cabbage (Brassica oleracea var. capitata L. (f. Rubra)) were recorded as containing very high levels of ascorbic acid among 66 vegetables tested. In fact, the highest amount of vitamin C (>2 mg/g FW) was recorded in red chilli (Isabelle et al., 2010). In another study, 32 accessions belong to four pepper species, viz. Capsicum annuum, Capsicum frutescens, Capsicum chinense and C. baccatum, vitamin C levels ranged from 20.45 (C. baccatum) to 205.94 mg/100 g FW (C. annuum) (Wahyuni, Ballestera, Sudarmonowatib, Binoa, & Bovya, 2011). Similar studies on 63 to 216 accessions of C. chinense, obtained from North, Central, and South America, contained up to 1466 mg vitamin C/100 g FW (Antonious, Lobel, Kochhar, Berke, & Jarret, 2009; Jarret, Berke, Baldwin, & Antonious, 2009). Estimated daily intake of fresh Capsicum fruits by Americans was about 22 g in 2014 (Wells, Bond, & Thornsbury, 2015). Several pepper genotypes are able to supply between 50% to more than 100% of the recommended daily intake (RDI) of vitamin C (Howard, Talcott, Brenes, & Villalon, 2000; Wahyuni et al., 2013). These findings suggest there is a scope for further exploration of Capsicum species for vitamin C supply.

Hancock and Viola (2005) and Gest, Gautier, and Stevens (2013) have reviewed various aspects of vitamin C biosynthesis in plants. Vitamin C synthesis in plants involves myo-inositol, l-gulose, l-galactose and/or d-galacturonic acid pathways. Not all the enzymes in these pathways have been identified in plants. However, l-gulose and l-galactose pathways are routed from GDP-D-mannose. Many biosynthetic pathways for vitamin C in higher plants might have a role in tissue- and organ-specific differences (Hancock & Viola, 2005). The majority of plants and animals synthesize ascorbic acid from d-glucose or d-galactose (Naidu, 2003), both reducing sugars. It is possible that the GDP-mannose pathway is the major vitamin C biosynthesis pathway in Arabidopsis (Dowdle, Ishikawa, Gatzek, Rolinski, & Smirnoff, 2007), but an alternative d-galacturonic acid pathway also exists in strawberry (Agius et al., 2003) and tomato (Badejo et al., 2012). These pathways might regulate vitamin C levels, with other pathways, or exhibit stage-specific response in these fruits (Badejo et al., 2012; Cruz-Rus, Amaya, Sanchez-Sevilla, Botella, & Valpuesta, 2011). Marín, Ferreres, Tomás-Barberán, and Gil (2004) reported that in sweet peppers (C. annuum L.), vitamin C accumulation increased with maturity and reached the highest levels in red ripened fruits. In another study, however, vitamin C levels in tomato and bell pepper (C. annuum) fruits decreased 74 and 51 days, respectively, after the fruit set (Yahiaa, Contreras-Padillaa, & Gonzalez-Aguilarb, 2001). From these reports, it is not clear whether vitamin C accumulation in pepper fruits is specific to genotype or species. Investigation of a large number of genotypes in a species may reveal the true pattern of vitamin C accumulation in this species.

Earlier studies on vitamin C content in Capsicum species were limited to few genotypes, regions or continents. Controversial reports exists on the stage in fruit development at which highest vitamin C is accumulated. Similarly, the relationship between reducing sugars and vitamin C in C. baccatum genotypes, which are widespread throughout the South America, is also not clear. Thus, the objective of this study was to analyze vitamin C in the world collection of 123 C. baccatum genotypes, and understand better the relationships between vitamin C and reducing sugars concentrations and fruit development. In this study, fully matured (un-ripened) and ripened fruit, which are the two major stages in harvest and consumption, were analyzed for vitamin C and reducing sugars, specifically d-glucose and d-galactose. We also attempted to identify the genotypes that might be able to supply at least half the RDA of vitamin C in human diet.

2. Materials and methods

2.1. Collection of fruit samples

Matured unripe and ripened fruits from 123 genotypes of C. baccatum were examined in this study. These genotypes were obtained previously from the Asian Vegetable Research and Development Center (AVRDC), Taiwan. This collection represents 22 countries, viz. Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Ecuador, El Salvador, France, Germany, Guatemala, Guyana, India, Jamaica, Kenya, Mexico, Netherlands, Paraguay, Peru, UK, USA and Zambia. All these genotypes were grown in a field at Sissonville (WV, USA) during the summer of 2013 using standard cultural practices. Three plants were selected randomly from each genotype for sample collection. For each stage approximately 300 g (not less than five fruits when fruit size was bigger) of fruits were collected from each plant in a plastic zipper bag. Three zipper bags of fruits collected from three independent plants in each genotype were kept in a larger zipper bag and transferred to laboratory on ice.

Fruits from each zipper bag dipped in sufficient liquid nitrogen until frozen and returned to the same zipper bag before being stored at −80 °C for further analysis.

2.2. PBS extraction

From stored samples, approximately 20 g of fruits (not less than five fruits when size was bigger) from each plant were used to isolate pericarp. A small portion of the pericarp from each fruit was pooled to make up 2.5 g. This pooled sample was ground to fine paste with sand in a pestle and mortar, and mixed with 5 ml of ice cold phosphate buffered saline (PBS; without calcium chloride; without magnesium chloride; pH 7.4) (Life Technologies, Grand Island, USA). This mixture was centrifuged at 5000 × g at 5–8 °C for 5 min, and the supernatant collected and stored at −80 °C.

2.3. Estimation of pericarp dry matter

After separating the pericarp for extraction, remainder from all fruit of the same genotype was pooled, weighed, and dried in an oven at 65 ± 2 °C for 72 h. After drying, samples were weighed and the percentage dry matter estimated.

2.4. Estimation of vitamin C

Vitamin C (l-ascorbic acid) in extracted samples was estimated using a protocol adopted from Kapur et al. (2012) with modifications. Briefly, extracts were thawed on equal amounts of ice and water, and kept on ice until use. Samples were vortexed before and after every step in the procedure. 500 µL was mixed with an equal amount of 3% metphosphoric acid (Sigma–Aldrich, St. Louis, USA) and the mixture centrifuged at 10,000×g for 15 min in a table top microcentrifuge (eppendorf, Hauppauge, USA). 280 µL of the supernatant was collected and mixed with 14 µL of bromine concentrate (0.05 mol L−1 commercial solution; Sigma–Aldrich). To this solution, 14 µL of 4% thiourea (Sigma–Aldrich) was added and mixed well. Then, 70 µL of 2% DNPH (2,4-dinitrophenylhydrazine) (Sigma–Aldrich) was added and the mixture incubated at 35 ± 2 °C for 3 h. After incubation, the samples were kept on ice and 350 µL of cold sulfuric acid (85%) (Sigma–Aldrich) added. After 5 min, 80 µL was transferred to a glass 96 well plate (Cayman Chemical, Ann Arbor, USA), and the absorbance read at 520 nm in a microplate reader (Synergy HT™, BioTek Instruments, Winooski, USA).

Metphosphoric acid (3%) was prepared by dissolving 15 g of metphosphoric acid in 40 mL of glacial acetic acid (Sigma–Aldrich) and made up to 500 mL with distilled water. Sulfuric acid (4.5 mol L−1) was used as a solvent for thiourea and DNPH solutions. DNPH solution was filtered using glass microfiber filters (GE Healthcare Bio-Sciences, Pittsburgh, USA). Freshly prepared ascorbic acid in PBS was used as a standard.

2.5. Estimation of reducing sugars

Reducing sugars in the samples were estimated using a protocol adopted from Perla, Holm, and Jayanty (2012). Glucose (Sigma–Aldrich) in PBS was used as a standard.

2.6. Statistical analysis

Unless otherwise stated, all the experiments were conducted with six replicates, and data are presented as mean ± standard deviation. Statistical analysis was performed using SAS® software (Version 9.4, Cary, NC) using BASE SAS, DATA step, PROC IMPORT, PROC CONTENTS, PROC SORT, PROC TRANSPOSE, PROC FORMAT, PROC CORR, PROC REG, PROC UNIVARIATE, PROC SGSCATTER, PROC SGPLOT, PROC TRANSREG, PROC STDIZE, PROC GLM, PROC NPAR1WAY, PROC SQL, PROC MEANS, PROC TABULATE, PROC PRINT and SAS MACRO programs. Pearson correlation analysis, analysis of variance (ANOVA), and Student–Newman–Keuls (SNK) test were performed on parametric datasets at the p ≤ 0.05 significance level. Non-parametric data sets were analyzed using Kruskal–Wallis test.

3. Results and discussion

3.1. Large variation exists in vitamin C levels in the world collection of C. baccatum genotypes

Parametric vitamin C concentrations in the pericarp of matured unripe and ripe fruits from the world collection of C. baccatum genotypes are presented in Table 1. The highest amount of vitamin C was found in the ripened fruits of Bird’s eye hot peppers (strain 3) (50.44 mg g−1 DW) originating from Guyana. The matured unripe fruits of the genotype VI028776 (Argentina) contained the least ascorbic acid (2.54 mg g−1 DW). Combined mean data for the both, matured unripe and ripen fruits suggested the top five genotypes, with highest vitamin C levels, were Bird’s eye hot peppers (strain 3) (49.78 mg g−1 DW; Guyana), VI044347 (39.82 mg g−1 DW; India), PI 543178 01 SD (39.3 mg g−1 DW; Bolivia), VI028794 (29.52 mg g−1 DW; Jamaica), and VI013034 (26.87 mg g−1 DW; UK). Compared with ripe fruit, VI028794 did not accumulate significant amounts of vitamin C at the matured unripe stage. VI028776 (3.31 mg g−1 DW; Argentina), VI029111 (3.49 mg g−1 DW; Brazil), VI029079 (3.66 mg g−1 DW; Ecuador), VI012959 (4.36 mg g−1 DW; Germany), and VI029047 (4.51 mg g−1 DW; India) were the five genotypes with least vitamin C. These findings suggest there is a large variation in parametric vitamin C concentrations among the world collection of C. baccatum genotypes, and this variation could be attributed to accumulation of significant amounts of vitamin C at either one or both stages in fruit development. This kind of large variation in total ascorbic acid values among large number of genotypes was also reported in C. chinense recently (Jarret et al., 2009).

Table 1.

Vitamin C (mg g−1 DW) in the pericarp of matured and ripened fruits of world collection of C. baccatum genotypes.

S. No. Genotype Origin Matured (M) Ripened (R) Combined (C) SNK^
Mean Std Mean Std Mean Std M R C
1 281408 01 SD Peru 10.72 1.04 10.27 1.07 10.49 1.03
2 Aji amarillo small Peru 7.72 0.70 6.71 0.46 7.22 0.77
3 Aji benito hot peppers Bolivia ND ND 6.31 0.46 6.31 0.46
4 Aji cito hot peppers Peru 9.98 0.77 4.29 0.33 7.14 3.02
5 Aji colorado hot peppers Bolivia ND ND 7.06 0.66 7.06 0.66
6 Aji habanero hot peppers Mexico 13.17 1.27 14.15 2.79 13.66 2.13
7 Bird’s eye hot peppers (strain 3) Guyana 49.12 5.85 50.44 16.87 49.78 12.06 a a a**
8 CGN16973 Bolivia 25.22 2.35 16.86 10.60 21.04 8.53
9 CGN17241 USA 6.31 0.46 6.22 0.34 6.27 0.39
10 CGN19233 Peru 29.40 2.84 13.76 0.97 21.58 8.42
11 CGN21479 Peru 29.47 2.76 10.64 0.83 21.40 9.89
12 CGN21513 Bolivia 12.09 0.98 6.67 0.46 9.38 2.93
13 CGN22834 Brazil 11.50 0.75 5.82 1.16 8.66 3.11
14 CGN22858 Brazil 6.59 0.65 7.00 0.30 6.82 0.50
15 CGN23763 Brazil 8.26 0.38 4.54 0.38 6.40 1.98
16 GRIF 9219 01 SD Costa Rica 8.22 0.66 8.43 0.78 8.32 0.70
17 PI 159252 01 SD USA 18.44 1.77 13.13 1.09 15.79 3.10
18 PI 215699 02 SD Peru 16.91 1.28 8.69 0.72 12.80 4.41
19 PI 215700 01 SD Peru 21.99 1.54 7.87 0.85 14.93 7.47
20 PI 238061 01 SD Bolivia ND ND 7.21 0.48 7.21 0.48
21 PI 497974 01 SD Brazil 12.59 0.97 NP NP 14.10 1.97
(15.60) (1.48)
22 PI 543178 01 SD Bolivia 41.23 4.59 37.37 4.12 39.30 4.62 a bc ab*
23 PI 640885 01 SD India 29.08 3.40 13.76 0.94 21.42 8.35
24 Uba tuba (Christmas bell) Brazil 10.07 0.84 9.26 0.75 9.66 0.87
25 VI012279 Ecuador 19.17 1.33 9.72 0.63 14.44 5.04
26 VI012422 USA 9.14 0.78 10.93 0.43 10.04 1.11
27 VI012673 UK 19.53 1.16 4.41 0.41 11.97 7.94
28 VI012898 France 12.40 1.04 16.99 1.04 14.69 2.59
29 VI012959 Germany 4.17 0.35 4.55 0.24 4.36 0.35 w r
30 VI012983 USA 10.51 1.11 10.51 1.21 10.51 1.11
31 VI013034 UK 24.88 2.31 28.86 2.67 26.87 3.16 b*
32 VI013036 Germany 6.28 0.39 9.34 0.92 7.81 1.74
33 VI013261 USA ND ND 30.55 2.95 30.55 2.95 b*
34 VI013262 USA 42.24 5.09 11.22 0.88 26.73 16.57 ab *
35 VI013290 UK 22.20 1.75 7.96 0.73 15.08 7.54
36 VI013395 Paraguay 17.22 1.22 10.04 0.86 13.63 3.88
37 VI013425 Argentina 12.08 1.11 6.38 0.42 9.23 3.08
38 VI013462 UK 17.35 1.37 5.09 0.50 11.22 6.48
39 VI013477 Netherlands 8.67 0.70 7.16 1.25 7.91 1.25
40 VI013973 El Salvador 14.06 1.04 7.30 0.75 10.68 3.64
41 VI014229 Unknown 11.39 0.89 8.03 0.71 9.71 1.91
42 VI014230 Peru 17.09 1.32 37.38 5.03 27.23 11.16 bc *
43 VI014270 Costa Rica ND ND 6.48 0.62 6.48 0.62
44 VI014892 Ecuador 11.39 0.77 13.55 1.28 12.47 1.52
45 VI028657 Costa Rica 10.94 0.71 15.89 1.83 13.42 2.90
46 VI028776 Argentina 2.54 0.14 4.08 1.01 3.31 1.06 y w r
47 VI028777 Bolivia 13.08 0.85 NP NP 102.88 95.22 ***
(192.68) (24.32)
48 VI028780 Bolivia 17.44 1.21 11.01 0.88 14.22 3.51
49 VI028782 Brazil 13.67 1.35 7.55 0.60 10.61 3.35
50 VI028788 Chile 26.43 3.51 6.15 0.47 16.29 10.85
51 VI028791 Costa Rica 8.91 0.70 9.87 0.96 9.39 0.95
52 VI028792 Ecuador 9.16 0.58 3.62 0.21 6.39 2.92 wx
53 VI028793 Ecuador 14.53 0.97 13.41 1.15 13.97 1.17
54 VI028794 Jamaica 23.93 2.58 35.11 7.74 29.52 8.02 cd b*
55 VI028795 Mexico 6.26 0.50 5.44 0.47 5.85 0.63
56 VI028797 Mexico 13.99 1.13 6.44 0.47 10.75 3.98
57 VI028798 Paraguay 34.45 2.92 9.01 0.89 21.73 13.44
58 VI028867 Brazil ND ND 11.20 0.87 11.20 0.87
59 VI028870-A Brazil 43.45 5.74 11.75 1.12 27.60 17.02 ab *
60 VI028870-B Brazil 21.03 1.87 14.95 0.48 17.99 3.43
61 VI028873 Brazil 15.90 1.39 17.58 1.33 16.74 1.56
62 VI028878 Brazil 11.56 1.20 16.61 1.80 14.08 3.02
63 VI028886 Brazil 34.45 2.78 13.94 1.01 24.20 10.90 *
64 VI028890 Brazil 20.57 1.67 9.47 0.81 15.02 5.93
65 VI028895 Brazil 4.26 0.25 NP NP 3.32 1.01 r
(2.37) (0.21)
66 VI028896 Brazil 31.44 3.47 7.83 0.81 19.63 12.56
67 VI028897 Brazil 14.75 1.23 5.60 0.37 10.17 4.86
68 VI028901 Brazil 13.57 0.81 6.69 0.46 10.13 3.64
69 VI028902 Brazil 7.93 0.59 3.65 0.27 5.79 2.28 wx
70 VI028910 Brazil 14.51 1.22 7.94 0.55 11.22 3.55
71 VI028911 Brazil 16.19 1.27 9.99 0.98 13.09 3.41
72 VI028939 USA 17.01 1.28 5.49 0.38 11.25 6.08
73 VI028942 USA 13.26 1.27 6.67 0.56 9.97 3.57
74 VI028968 Chile 8.26 0.72 17.71 1.43 12.98 5.05
75 VI028969 Colombia 11.81 0.91 5.88 0.43 8.84 3.17
76 VI028971 Ecuador 16.22 1.25 7.09 0.46 11.66 4.86
77 VI028973 Ecuador NP NP 10.35 0.69 5.36 5.23
(0.37) (0.02)
78 VI029021 Bolivia 12.14 0.65 5.63 0.39 8.89 3.40
79 VI029022 Bolivia 8.76 0.74 5.89 0.53 7.33 1.62
80 VI029023 Bolivia ND ND 4.32 0.44 4.32 0.44 r
81 VI029024 Bolivia 7.15 0.56 11.13 0.95 9.14 2.21
82 VI029025-A Bolivia ND ND 9.07 1.04 9.07 1.04
83 VI029025-B Bolivia ND ND 3.30 0.23 3.30 0.23 x r
84 VI029025-C Bolivia 8.64 0.79 5.77 0.45 7.20 1.62
85 VI029026 Bolivia NP NP 8.50 0.62 4.93 3.76
(1.36) (0.09)
86 VI029033-A Bolivia ND ND 17.46 1.63 17.46 1.63
87 VI029044 Brazil 11.74 1.01 11.64 0.74 11.69 0.84
88 VI029047 India 4.62 0.41 4.39 0.39 4.51 0.40 qr
89 VI029050 Guatemala NP NP 5.83 0.45 4.08 1.86
(2.33) (0.14)
90 VI029057 Brazil 28.25 2.38 9.65 0.71 18.95 9.86
91 VI029060 Chile NP NP 6.56 0.48 4.19 2.15
(2.41) (0.16)
92 VI029062 Ecuador 20.87 1.77 12.81 0.99 16.84 4.42
93 VI029076 Kenya 4.17 0.30 4.91 0.35 4.54 0.49 w
94 VI029079 Ecuador 4.02 0.26 3.30 0.27 3.66 0.45 w x r
95 VI029081 India 11.61 1.30 17.83 1.99 14.72 3.62
96 VI029084 Brazil 7.29 0.50 11.90 1.29 9.59 2.58
97 VI029085 Brazil 6.64 0.33 7.02 0.41 6.80 0.40
98 VI029091 Brazil 33.06 2.50 NP NP 30.46 4.09 ab*
(27.00) (3.07)
99 VI029097 Brazil 15.05 1.06 14.88 1.36 14.96 1.17
100 VI029098-B Brazil 7.90 0.62 9.25 0.71 8.67 0.95
101 VI029101 Brazil 19.56 1.50 5.22 0.39 12.39 7.56
102 VI029104 Brazil 8.98 0.78 6.53 0.50 7.75 1.42
103 VI029110 Brazil 15.27 1.26 6.23 0.42 10.75 4.81
104 VI029111 Brazil 2.75 0.20 4.24 0.29 3.49 0.81 y r
105 VI029112 Brazil 19.47 1.99 7.86 0.77 13.67 6.23
106 VI029113 Brazil 12.54 1.13 11.52 1.06 12.03 1.17
107 VI029117 Brazil 9.51 0.67 3.24 0.27 6.37 3.31 x
108 VI029124-A Bolivia 20.10 1.43 21.17 3.89 20.64 2.85
109 VI029124-B Bolivia 5.30 0.16 9.59 0.64 7.45 2.29
110 VI029511 Colombia 12.78 1.02 11.21 0.87 11.99 1.22
111 VI031222 Zambia ND ND 6.96 0.79 6.96 0.79
112 VI037435 Brazil 12.67 1.03 6.92 0.51 9.80 3.10
113 VI044307 Unknown 15.95 1.38 12.15 1.65 14.05 2.46
114 VI044310 Peru 14.30 1.17 8.02 0.78 11.16 3.41
115 VI044347 India 48.82 4.13 30.81 2.78 39.82 9.99 a d ab*
116 VI044352 Unknown 16.94 1.22 7.68 0.64 12.31 4.92
117 VI047059-B Peru 24.72 2.29 4.78 0.32 14.75 10.53
118 VI049287 USA 8.23 0.83 5.74 0.43 6.99 1.45
119 VI049327 USA 10.68 0.93 18.00 1.75 14.34 4.05
120 VI057369 USA 7.58 0.51 10.19 0.79 8.88 1.50
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Statistical analysis was performed after logarithmic transformation of data. DW: Dry Weight. Std: Standard deviation. ND: Not Determined. NP: Non-Parametric (Refer Kruskal–Wallis test for NP-data; Fig. 1). Values in parenthesis are NP values. SNK: Student–Newman–Keuls test.

^

Top as well as bottom 5 genotype-ranks in each stage are denoted separately by lower case letters in descending order; Means with the same letter are not significantly different. More than 5 rankings are displayed when ranked genotypes had ’ND’ or ’NP’ in any stage.

*

Each 2 g DW sample supplies ≥ 50% RDA of vitamin C.

**

Each 2 g DW sample supplies ≥ 100% RDA of vitamin C.

***

Each 2 g DW sample supplies ≥ 200% RDA of vitamin C. RDA of vitamin C for adult men = 90 mg day−1. Number of observations/stage/genotype: 6–8.

Distribution of Wilcoxon scores for non-parametric vitamin C data is presented in Fig. 1. Among them, only a few genotypes (matured stage of VI028777, Bolivia; and both the stages of VI028796, Mexico; and VI057372, USA) accumulated higher concentrations of vitamin C compared with ripe Bird’s eye hot peppers (strain 3) (Guyana). Similarly, only a few genotypes (matured stage of VI028973, Ecuador; VI029026, Bolivia; and VI029050, Guatemala; and both the stages of VI029087, Brazil) synthesized less vitamin C than the mature unripe stage of VI028776 (Argentina). Vitamin C concentrations in other genotypes (matured stage of VI028895, Brazil; and VI029060, Chile; and ripened stage of PI 49797401 SD, Brazil; and VI029091, Brazil) were within the range identified in the parametric data, as shown in Table 1. Combined mean values of vitamin C for the both, matured unripe and ripen fruits in VI028777 (102.89 mg g−1 DW), VI028796 (242 mg g−1 DW) and VI057372 (110.6 mg g−1 DW) were two- to five-times higher than combined mean value for Bird’s eye hot peppers (strain 3) (49.78 mg g−1 DW) (Table 1; Fig. 1). Combined mean value for vitamin C in VI029091 (30 mg g−1 DW) was much less than combined mean value for Bird’s eye hot peppers (strain 3).

Fig. 1.

Fig. 1

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Kruskal–Wallis test for non-parametric vitamin C data was performed on either one or two developmental fruit stages of 11 genotypes (n = 6). (A) Vitamin C levels in fruit pericarp (mg g−1 DW); (B) Distribution of Wilcoxon scores for vitamin C levels. Matured and ripened stages of fruits are denoted by ‘M’ and ‘R’, respectively. Genotypes with maximum (‘Max’) and minimum (‘Min’) vitamin C levels from parametric data are included here for reference (refer Table 1). VI028796, VI029087 and VI057372 are originated from Mexico, Brazil and USA, respectively. Refer Table 1 for origin of all other genotypes.

Estimated daily intake of fresh Capsicum fruits by Americans was about 22 g in 2014 (Wells et al., 2015). The moisture content of harvested fruits in the present study was about 90% (data not shown). Thus, 22 g of fresh Capsicum fruits is equal to 2.2 g of dry fruits. Therefore, in the present study, any genotype that accumulated ≥45 mg of vitamin C (combined mean value) in 2 g of fruit pericarp DW would provide more than half the RDA for vitamin C (Supplementary Table S1; Table 1; Fig. 1). We identified one genotype (VI028796, Mexico) that would provide ≥ 500% RDA, two genotypes (VI028777, Bolivia; and VI057372, USA) ≥ 200% RDA, one genotype (BIRD’S EYE HOT PEPPER STRAIN 3, Guyana) ≥ 100% RDA, and ten genotypes (PI 543178 01 SD, Bolivia; VI013034, UK; VI013261, USA; VI013262, USA; VI014230, Peru; VI028794, Jamaica; VI028870-A, Brazil; VI028886, Brazil; VI029091, Brazil; and VI044347, India) with more than half the RDA for vitamin C in the collection. Similar reports, with up to 461% of the RDA for vitamin C, have been published describing different Capsicum species (Howard, Smith, Wagner, Villalon, & Burns, 1994; Howard et al., 2000; Lee, Howard, & Villalon, 1995; Osuna-Garcia, Wall, & Waddell, 1998; Simmone, Simmone, Eitenmiller, Mills, & Green, 1997). Genotypes of C. baccatum from this study might serve as functional foods for vitamin C in the human diet.

3.2. Large variation exists in reducing sugar levels in the world collection of C. baccatum genotypes

Parametric reducing sugar concentrations in the pericarp of mature unripe and ripen fruits of the world collection of C. baccatum genotypes are presented in Table 2. Among these, ripe VI029085 (Brazil) and mature unripe VI028794 (Jamaica) recorded the highest (700 mg g−1 DW) and lowest (41 mg g−1 DW) amounts of reducing sugars, respectively. Among the combined mean values, the five genotypes with highest amounts of reducing sugars were Uba tuba (christmas bell) (458 mg g−1 DW; Brazil), VI012959 (472 mg g−1 DW; Germany), VI013462 (468 mg g−1 DW; UK), VI028902 (449 mg g−1 DW; Brazil), and VI029101 (483 mg g−1 DW; Brazil). On the other hand, the five genotypes with lowest combined mean values for reducing sugars were VI028794 (109 mg g−1 DW; Jamaica), VI044347 (130 mg g−1 DW; India), VI028896 (155 mg g−1 DW; Brazil), VI013973 (162 mg g−1 DW; El Salvador), and Bird’s eye hot peppers (strain 3) (164 mg g−1 DW; Guyana). As with vitamin C, there was considerable variation in parametric reducing sugar concentrations in the fruits, and this variation could be attributed to the accumulation reducing sugars at different stages in fruit development. Large variations in the concentrations of sugars, such as sucrose, glucose and fructose, were also reported among the genotypes of C. chinense (Jarret et al., 2009). Furthermore, reducing sugars, total soluble solid content, and titratable acidity are known to increase during ripening of peppers (Martínez, Curros, Bermúdez, Carballo, & Franco, 2007; Osuna-Garcia et al., 1998).

Table 2.

Reducing sugars (mg g−1 DW) in the pericarp of matured and ripened fruits of world collection of C. baccatum genotypes.

S. No. Genotype Origin Matured (M) Ripened (R) Combined (C) SNK^
Mean Std Mean Std Mean Std M R C
1 281408 01 SD Peru 218.44 7.40 417.82 14.52 318.13 104.70
2 Aji amarillo small Peru 245.19 17.03 477.41 29.57 361.30 123.44
3 Aji benito hot peppers Bolivia ND ND 669.99 15.30 669.99 15.30 b a
4 Aji cito hot peppers Peru 271.70 8.90 384.11 18.38 327.91 60.30
5 Aji colorado hot peppers Bolivia ND ND 494.74 9.80 494.74 9.80 b
6 Aji habanero hot peppers Mexico 137.71 3.14 389.63 5.30 263.67 131.63
7 Bird’s eye hot peppers (strain 3) Guyana 67.29 1.70 260.60 22.60 163.94 102.10 y q
8 CGN16973 Bolivia 87.96 5.98 343.07 2.59 215.51 133.30
9 CGN17241 USA 149.51 7.05 327.98 19.79 238.74 94.27
10 CGN19233 Peru 149.95 7.21 344.28 8.16 247.12 101.75
11 CGN21479 Peru 165.44 7.66 426.13 26.52 277.16 135.00
12 CGN21513 Bolivia 259.94 10.22 473.85 19.74 366.89 112.71
13 CGN22834 Brazil 207.69 7.10 484.76 21.14 346.23 145.48
14 CGN22858 Brazil 152.99 2.21 311.67 37.11 243.67 85.93
15 CGN23763 Brazil 156.29 2.48 500.77 44.62 328.53 182.41
16 GRIF 9219 01 SD Costa Rica 147.49 9.53 323.75 38.20 235.62 95.80
17 PI 159252 01 SD USA 138.32 9.62 337.79 11.80 238.05 104.68
18 PI 215699 02 SD Peru 170.30 10.73 607.53 75.33 388.92 234.03
19 PI 215700 01 SD Peru 201.39 11.26 258.01 5.73 229.70 30.77
20 PI 238061 01 SD Bolivia ND ND 351.52 8.58 351.52 8.58
21 PI 497974 01 SD Brazil 252.29 5.55 SP SP 456.22 213.06
(660.15) (5.55)
22 PI 543178 01 SD Bolivia 167.81 12.76 376.61 33.35 272.21 111.67
23 PI 640885 01 SD India 136.66 4.60 418.21 8.85 277.43 147.19
24 Uba tuba (Christmas bell) Brazil 350.46 16.69 565.76 12.35 458.11 113.31 r b
25 VI012279 Ecuador 195.96 11.07 498.92 29.86 347.44 159.66
26 VI012422 USA 102.43 3.87 392.17 13.40 247.30 151.61
27 VI012673 UK 338.22 21.72 519.32 22.89 428.77 96.94 r
28 VI012898 France 179.83 3.60 505.91 18.62 342.87 170.77
29 VI012959 Germany 262.98 4.91 680.48 29.15 471.73 218.94 ab b
30 VI012983 USA 157.27 23.94 361.51 18.82 259.39 108.62
31 VI013034 UK 72.61 3.47 272.20 4.34 172.41 104.30 xy
32 VI013036 Germany 215.42 13.39 465.59 6.60 340.51 131.04
33 VI013261 USA ND ND 368.18 22.45 368.18 22.45
34 VI013262 USA 289.85 14.92 497.40 8.26 393.63 109.00 yz
35 VI013290 UK 210.61 13.38 532.57 15.99 371.59 168.72
36 VI013395 Paraguay 131.75 3.28 481.42 22.13 306.59 183.23
37 VI013425 Argentina 175.51 13.73 448.19 5.77 311.85 142.76
38 VI013462 UK 247.60 6.26 687.33 30.25 467.46 230.59 ab b
39 VI013477 Netherlands 243.64 12.78 501.23 12.19 372.43 135.05
40 VI013973 El Salvador 120.44 8.57 203.55 4.25 162.00 43.88 mqu q
41 VI014229 Unknown 106.79 1.07 252.29 14.87 179.54 76.65
42 VI014230 Peru 131.67 6.09 362.76 23.21 247.22 121.76
43 VI014270 Costa Rica ND ND 272.55 17.77 272.55 17.77
44 VI014892 Ecuador 184.09 6.70 480.41 3.95 332.25 154.84
45 VI028657 Costa Rica 156.94 5.32 404.75 9.68 280.85 129.63
46 VI028776 Argentina 262.53 8.85 588.01 36.75 425.27 171.88
47 VI028777 Bolivia 162.40 8.90 SP SP 256.72 99.02 q
(351.04) (11.91)
48 VI028780 Bolivia 152.65 10.31 496.75 2.94 324.70 179.84
49 VI028782 Brazil 198.53 13.09 304.67 19.47 251.60 57.64
50 VI028788 Chile 232.10 10.56 444.52 21.81 338.31 112.13
51 VI028791 Costa Rica 135.67 1.73 386.25 27.34 260.96 132.16
52 VI028792 Ecuador 211.51 10.19 350.13 7.32 280.82 72.88
53 VI028793 Ecuador 186.63 2.71 421.52 7.31 304.07 122.78
54 VI028794 Jamaica 40.99 1.30 177.33 7.64 109.16 71.39 z u q
55 VI028795 Mexico 167.27 12.28 426.36 6.54 296.82 135.63
56 VI028797 Mexico 110.39 13.13 514.47 15.34 283.57 207.96
57 VI028798 Paraguay 166.49 4.13 473.76 13.01 320.12 160.73
58 VI028867 Brazil ND ND 486.68 17.75 486.68 17.75 b
59 VI028870-A Brazil 170.89 2.84 467.43 9.71 319.16 155.01
60 VI028870-B Brazil 251.93 1.80 549.25 23.18 400.59 156.06
61 VI028873 Brazil 124.31 1.99 377.29 11.26 250.80 132.34
62 VI028878 Brazil 93.11 1.63 332.34 10.49 212.72 125.14
63 VI028886 Brazil 148.29 7.29 461.99 14.40 305.14 164.18
64 VI028890 Brazil 138.12 2.15 395.81 10.83 266.97 134.78
65 VI028895 Brazil 296.17 20.08 SP SP 438.47 149.34 xyz
(580.78) (7.73)
66 VI028896 Brazil 82.71 3.54 226.57 4.31 154.64 75.22 xy jmq q
67 VI028897 Brazil 162.11 10.12 433.29 5.06 297.70 141.82
68 VI028901 Brazil 227.02 4.78 462.75 20.32 344.88 123.91
69 VI028902 Brazil 273.33 12.57 623.60 11.10 448.47 183.27 z c b
70 VI028910 Brazil 234.19 10.96 546.63 10.68 390.41 163.49
71 VI028911 Brazil 209.74 7.36 536.90 1.81 373.32 170.93
72 VI028939 USA 128.10 6.45 296.26 8.71 212.18 88.12
73 VI028942 USA 154.40 4.77 264.96 6.84 209.68 58.01
74 VI028968 Chile 184.24 6.70 471.68 13.19 327.96 150.44
75 VI028969 Colombia 179.92 11.73 493.64 12.97 336.78 164.26
76 VI028971 Ecuador 222.23 6.09 535.45 15.40 378.84 163.95
77 VI028973 Ecuador SP SP 335.55 20.07 255.82 84.39
(176.10) (3.37)
78 VI029021 Bolivia 159.76 8.53 364.28 78.89 262.02 118.71
79 VI029022 Bolivia 165.69 6.62 375.84 13.68 270.76 110.22
80 VI029023 Bolivia ND ND 578.38 49.61 578.38 49.61 ab
81 VI029024 Bolivia 182.76 7.53 428.71 11.93 305.74 128.80
82 VI029025-A Bolivia ND ND 402.51 11.34 402.51 11.34
83 VI029025-B Bolivia ND ND 277.87 15.04 277.87 15.04
84 VI029025-C Bolivia 171.76 5.60 352.03 36.32 261.90 97.35
85 VI029026 Bolivia SP SP 481.53 15.88 313.16 176.20 b
(144.79) (4.03)
86 VI029033-A Bolivia ND ND 444.98 7.22 444.98 7.22
87 VI029044 Brazil 186.34 8.98 384.69 21.52 285.52 104.77
88 VI029047 India 222.53 4.80 363.19 13.39 292.86 74.08
89 VI029050 Guatemala SP SP 451.97 21.82 315.53 143.93 b
(179.10) (20.66)
90 VI029057 Brazil 143.78 4.21 387.44 16.10 265.61 127.74
91 VI029060 Chile SP SP 558.14 39.10 351.94 186.98 ab
(197.28) (7.6)
92 VI029062 Ecuador 190.25 17.07 377.70 11.04 283.98 98.85
93 VI029076 Kenya 191.44 1.12 470.63 12.00 331.04 146.03
94 VI029079 Ecuador 254.22 10.26 539.73 10.01 396.97 149.41
95 VI029081 India 138.34 6.76 371.44 10.43 254.89 122.02
96 VI029084 Brazil 190.08 10.39 547.47 24.58 368.78 187.50
97 VI029085 Brazil 244.48 18.38 700.15 36.45 439.77 235.48 a
98 VI029091 Brazil 152.58 8.61 SP SP 349.16 235.95 q
(611.28) (19.20)
99 VI029097 Brazil 158.62 8.51 570.91 22.29 364.77 215.91
100 VI029098-B Brazil 223.52 12.59 426.63 40.61 339.58 108.76
101 VI029101 Brazil 301.25 6.97 665.48 15.90 483.36 190.58 xyz b b
102 VI029104 Brazil 268.22 16.37 570.49 14.76 419.36 158.55
103 VI029110 Brazil 162.27 7.55 366.63 16.91 264.45 107.45
104 VI029111 Brazil 270.50 18.34 454.23 44.75 362.37 101.34
105 VI029112 Brazil 212.89 10.29 608.18 23.81 410.54 207.17
106 VI029113 Brazil 206.53 7.71 426.99 12.33 316.76 115.55
107 VI029117 Brazil 179.58 6.53 452.55 16.24 316.06 143.04
108 VI029124-A Bolivia 96.13 5.32 234.80 23.85 165.46 74.27 jm
109 VI029124-B Bolivia 153.00 5.05 406.81 4.76 279.90 132.63
110 VI029511 Colombia 209.18 11.56 529.16 14.35 369.17 167.57
111 VI031222 Zambia ND ND 469.73 6.43 469.73 6.43 b
112 VI037435 Brazil 236.03 9.26 511.79 17.26 373.91 144.61
113 VI044307 Unknown 142.70 5.62 460.24 40.00 301.47 168.05
114 VI044310 Peru 203.46 17.51 447.41 12.96 325.43 128.24
115 VI044347 India 70.43 2.42 190.03 4.07 130.23 62.54 xy qu q
116 VI044352 Unknown 182.35 7.40 497.20 38.77 339.78 166.57
117 VI047059-B Peru 176.18 6.45 451.31 57.08 313.75 148.81
118 VI049287 USA 191.31 11.27 573.79 31.36 382.55 201.00
119 VI049327 USA 155.36 6.28 403.12 23.30 279.24 130.41
120 VI057369 USA 111.75 3.73 440.67 15.26 276.21 172.10
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DW: Dry Weight. Std: Standard deviation. ND: Not Determined. SP: Separated along with the corresponding non-parametric ascorbic acid data (Refer Kruskal–Wallis test for this data; Fig. 2). Values in parenthesis are SP values. SNK: Student–Newman–Keuls test.

^

Top as well as bottom 5 genotype-ranks in each stage are denoted separately by lower case letters in descending order. Means with the same letter are not significantly different. More than 5 rankings are displayed when ranked genotypes had ’ND’ or ’NP’ in any stage. Number of observations/stage/genotype: 6–8.

A second set of parametric reducing sugars data separated with the non-parametric vitamin C data are presented in Fig. 2. Unlike vitamin C (Fig. 1B), Wilcoxon scores for reducing sugars in PI49797401 SD (ripe), VI028777 (ripe), VI028796 (mature unripe and ripe), VI028895 (ripe), VI028973 (mature unripe), VI029026 (mature unripe), VI029050 (mature unripe), VI029060 (mature unripe), VI029087 (mature unripe and ripe), VI029091 (ripe), and VI057372 (mature unripe and ripe) (Fig. 2B) were distributed in the range between the highest (ripe VI029085, Brazil) and lowest (matured stage of VI028794, Jamaica) parametric data (Table 2). These findings also suggest the relationship between vitamin C and reducing sugars in this second group of genotypes is different from the relationship observed in the genotypes presented previously (Tables 1 and 2).

Fig. 2.

Fig. 2

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Kruskal–Wallis test for parametric data on reducing sugars was performed on either one or two developmental fruit stages of 11 genotypes (n = 6). Although parametric, this reducing sugars data was separated along with the corresponding non-parametric vitamin C data for comparison. (A) Reducing sugar levels in the fruit pericarp (mg g−1 DW); (B) Distribution of Wilcoxon scores for reducing sugar levels. Matured and ripened stages of fruits are denoted by ‘M’ and ‘R’, respectively. Genotypes with maximum (‘Max’) and minimum (‘Min’) reducing sugar levels from parametric data are included here for reference (refer Table 2). VI028796, VI029087 and VI057372 are originated from Mexico, Brazil and USA, respectively. Refer Table 1 for origin of all other genotypes.

3.3. Fruit developmental stage influence the levels of vitamin C and reducing sugars

Accumulation of vitamin C and reducing sugars at mature unripe and ripe stages of fruit development, the two major stages in harvest and consumption, are presented in Fig. 3. Overall, vitamin C levels in ripe fruit were significantly lower than at the mature unripe stage. A significant if weak negative correlation was observed between stage and vitamin C concentration (Pearson correlation coefficient: −0.33; p < 0.0001). Contrary to vitamin C, reducing sugar levels in ripe fruit were significantly higher than at the mature unripe stage. A strong positive correlation was identified between stage and reducing sugars (Pearson correlation coefficient: 0.81; p < 0.0001). Alós, Rodrigo, and Zacarías (2013) argued that the genotypes belonging to C. annuum reliably accumulated more ascorbic acid in ripe fruits. In the present study, a small fraction of C. baccatum genotypes exhibited a similar trend (Table 1; Fig. 1). In contrast, however, the majority of C. baccatum genotypes accumulated most vitamin C at the mature unripe stage, which appears to be a characteristic feature of C. baccatum genotypes (Fig. 3A). Similar genotype-dependent variability in total vitamin C content during ripening has been reported in tomato and watermelon (Ilahy, Hdider, Lenucci, Tlili, & Dalessandro, 2011; Tlili, Hdider, Lenucci, Ilahy, & Jebari, 2011). It has been postulated that these differences might exist due to either genetic variation or comparison of non-uniform or asynchronous stages of ripening (Alós et al., 2013). Similarly, other factors, such as environment, cultural practices and spontaneous mutations, also contribute to variability in vitamin C content at different stages of ripening (Ilahy et al., 2011; Tlili et al., 2011).

Fig. 3.

Fig. 3

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Effect of fruit developmental stage on accumulation of vitamin C and reducing sugars in the fruit pericarp of the world collection of C. baccatum genotypes. ANOVA was performed on parametric data after logarithmic transformation of vitamin C values (mg g−1 DW) (Refer Table 1 for data). Refer Table 2 for parametric data on reducing sugars (mg g−1 DW). SNK test was performed and means that are significantly different from each other in each analysis are represented by different letter in descending order (n = 688–766).

In certain C. annuum species, ascorbic acid concentrations are inversely correlated with expression of biosynthetic genes, and this feedback regulation of ascorbic acid homeostasis is further controlled by ascorbate oxidase. In tomato and bell pepper (C. annuum), vitamin C decreased from 74 and 51 days, respectively, after the fruit has set. These changes have also been associated with increased levels of ascorbate oxidase (Yahiaa et al., 2001). Although, ascorbate oxidase appeared to have an important role in the regulation of ascorbic acid levels during fruit development and ripening, mRNA levels could not explain differences in ascorbic acid concentration among the varieties examined (Alós et al., 2013). At the end of maturation, between 40 to 60 days after anthesis, there is a global decrease in gene expression in chili pepper fruits (Martínez-López, Ochoa-Alejo, & Martínez, 2014). Fruit ripening is an oxidative process and several antioxidants, including ascorbic acid, might be involved in scavenging reactive oxygen species during ripening (Gest et al., 2013). In one study, compared with green fruits, galactose in ripe red fruits approximately 80% lower. Hydrolysis of galactose by beta-galactosidase is thought to be the first event in bell pepper fruit ripening (Ogasawara, Abe, & Nakajima, 2007). On the other hand, increased levels of reducing sugars during ripening (Martínez et al., 2007; Osuna-Garcia et al., 1998) are an indication of decreased conversion of precursor sugars into vitamin C in the pepper fruits during ripening. Some portion of ascorbic acid might have been converted to organic acids (Ishakawa, Dowdle, & Smirnoff, 2006), which is evident from increased acidity in pepper fruits during ripening (Martínez et al., 2007). Together, it can be postulated that genotypes of C. baccatum accumulate more vitamin C in mature unripe fruits and these levels decrease in ripe fruits, probably due to decreased expression of ascorbic acid biosynthetic genes, hydrolysis of galactose, increased oxidation of ascorbic acid, and or its utilization during antioxidant mechanism or conversion to organic acids.

3.4. Negative relationship exists between vitamin C and reducing sugars

Reducing sugars with a potential aldehyde or keto group include glucose, galactose, lactose, fructose, arabinose and maltose. In plants, ascorbic acid is synthesized via l-gulose, myo-inositol, l-galactose and/or d-galacturonic acid pathways. d-glucose serves as a precursor for l-gulose and l-galactose pathways. l-galactose is an immediate precursor for ascorbic acid synthesis in l-galactose pathway (Hancock, & Viola, 2005). In majority of the plants, ascorbic acid is synthesized from d-glucose or d-galactose (Naidu, 2003). The relationship between reducing sugars and vitamin C at different stages of fruit maturation is presented in Fig. 4. There was a significant moderate negative relationship between the vitamin C and reducing sugars levels in the fruit pericarp (Fig. 4A) in mature unripe fruit. Pearson correlation coefficient of −0.44 (p < 0.0001) between vitamin C and reducing sugars clearly suggests 44% of the variation observed in pericarp vitamin C could be explained by reducing sugar levels in the pericarp of the genotypes shown in Tables 1 and 2. When fruit development stages were separated, this correlation value was reduced to −0.35 (p < 0.0001) in mature unripe and −0.33 (p < 0.0001) in ripe stages (Fig. 4 B and C). Together, these findings suggest that some portion of glucose and/or galactose in the reducing sugar pool might be converted to vitamin C in C. baccatum genotypes. On the other hand, these findings also suggest that non-parametric levels of vitamin C in 11 genotypes cannot be explained by reducing sugar levels alone (Figs. 1 and 2). This might be due to genetic variation associated with vitamin C synthesis in these genotypes or simply macro- or micro-environmental conditions during maturation and ripening of the fruit in the field.

Fig. 4.

Fig. 4

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Relationship between vitamin C and reducing sugars in the pericarp of fruits of world collection of C. baccatum genotypes. (A) Both stages; (B) matured stage; and (C) ripened stage. Statistical analysis was performed after logarithmic transformation of vitamin C and standardization of reducing sugars data. Total number of genotypes tested = 120; total number of observations = 1454; number of observations/stage/genotype = 6–8.

4. Conclusions

Fruits of 123 genotypes of C. baccatum originating from 22 countries, Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Ecuador, El Salvador, France, Germany, Guatemala, Guyana, India, Jamaica, Kenya, Mexico, Netherlands, Paraguay, Peru, UK, USA and Zambia, were analyzed for vitamin C and reducing sugars content in mature unripe and ripe fruit collected from field grown plants at Sissonville (WV, USA) during the summer 2013. Among the normal distributed (parametric) population, vitamin C and reducing sugar levels ranged between 2.54 to 50.44 and 41 to 700 mg g−1 DW of pericarp, respectively. Given the latest rate of fresh Capsicum fruit consumption in USA, fruits from 10 genotypes could supply more than half the RDA of vitamin C from 2 g of fruit pericarp on a dry weight basis. Four genotypes accumulated 100–500% the RDA of vitamin C. During fruit development, the highest amounts of vitamin C and reducing sugars accumulated in mature unripe and ripe fruit, respectively. An inverse relationship exists between reducing sugars and vitamin C (R2 = −0.44). Reducing sugars contributed about 44% of variation in the vitamin C content. Some genotypes accumulated higher or lower amounts of vitamin C than the normal population. This variation cannot be explained by reducing sugar levels in the fruits. Genotypes with more than half the RDA of vitamin C could serve as functional foods for vitamin C in human diet.

Supplementary Material

Supplemental Table

Acknowledgments

This work was supported by a grant from USDA-NIFA (Contract No. 2010-38821-21574); and WV-INBRE Center for Natural Products Research (NIH), sub-award No. P1400846 (NIH Prime award No. 5P20GM103434-13).

Footnotes

Appendix A. Supplementary data

Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.foodchem.2016.01.135.

Contributor Information

Venu Perla, Email: venuperla@yahoo.com.

Padma Nimmakayala, Email: padma@wvstateu.edu.

Marjan Nadimi, Email: marjan.nadimi51@gmail.com.

Suresh Alaparthi, Email: salaparthi@wvstateu.edu.

Gerald R. Hankins, Email: ghankins@wvstateu.edu.

Andreas W. Ebert, Email: andreas.ebert@worldveg.org.

Umesh K. Reddy, Email: ureddy@wvstateu.edu.

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