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LWT 40 (2007) 121–129 www.elsevier.com/locate/lwt
Antioxidant constituents in some sweet pepper (Capsicum annuum L.) genotypes during maturity N. Deepaa, Charanjit Kaura, Binoy Georgea, Balraj Singhb, H.C. Kapoorc, a
Division of Post Harvest Technology, Indian Agricultural Research Institute, New Delhi 110012, India b Indo-Israel Project, Indian Agricultural Research Institute, New Delhi 110012, India c Division of Biochemistry, Indian Agricultural Research Institute, New Delhi 110012, India
Received 7 February 2005; received in revised form 27 September 2005; accepted 27 September 2005
Abstract Changes in total phenolics, antioxidant activity (AOX), carotenoids, capsaicin and ascorbic acid were monitored during three maturity stages in 10 genotypes of sweet pepper. In an attempt to explain the variations during maturity stages (green, intermediate and red/ yellow), the data was expressed both on fresh and dry weight basis. All the antioxidant constituents (phenolics, ascorbic acid and carotenoids) and AOX, when expressed on fresh weight basis in general, showed an overall increasing trend during maturity in all the genotypes studied. On dry weight basis, phenolic content declined in majority of the genotypes during maturity to red stage. This decline was significant (Po0:05) in Parker, Torkel, HA-1038 and Flamingo. Genotype Flamingo and Golden Summer had the highest phenolic content of 852.0 mg 100 g1 and 720.5 mg 100 g1, at their final red and yellow maturity stages, respectively. With maturation, most of the cultivars showed a declining trend with regard to capsaicin content while total carotenoids and b-carotene content increased significantly. Anupam was a promising genotype in terms of both total carotenoids and b-carotene content. Ascorbic acid content declined progressively with advancing maturity. Genotype HA-1038 had the maximum content (3030 mg 100 g1 dwb) at the green stage. AOX in general, increased with maturity and registered a 1.30–1.95fold increase from green to red stage. The study proposes the nutritional significance of consuming sweet peppers at the red maturity stage because of enhanced functional properties. Overall genotype Flamingo and Anupam represent superior genotypes for both nutrition and germplasm improvement. r 2005 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved. Keywords: Capsicum; Antioxidant activity; b-carotene; Total phenolics
1. Introduction A wealth of information and scientific evidences are rapidly accumulating that show the beneficial effects of wide variety of food components on human health. In this context, fruits and vegetables are immensely valued not only for their nutritional value but also for their potential health functionality against various degenerative diseases such as cancer, cardiovascular, cataract, diabetes and neuro-degenerative diseases like Alzheimer’s and Parkinson’s (Kaur & Kapoor, 2001). This direct and positive relationship between health and diet has now attracted the Corresponding author. Tel.: +91 9811228802.
E-mail address:
[email protected] (H.C. Kapoor).
attention of plant breeders and biotechnologists who are directing their efforts to breed genotypes with high content of phytochemicals (Cevallos-Casals, Byrne, Okie, & Cisneros-Zevallos, 2005). Levels of these antioxidants can vary with genotype, stage of maturity, plant part consumed, and conditions during growth and post harvest handling. Thus it becomes pertinent to study these variations in different genotypes during maturity to select the best for health benefits. In addition to the sensory attributes of colour, pungency and aroma, sweet peppers, among vegetables, have become extremely popular for the abundance and the kind of antioxidants they contain. Among the antioxidant phytochemicals, polyphenols deserve a special mention due to their free radical scavenging properties. These compounds
0023-6438/$30.00 r 2005 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.lwt.2005.09.016
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whose levels vary strongly during growth and maturation are also important because of their contribution to pungency, bitterness, colour and flavour of fruits (Estrada, Bernal, Diaz, Pomar, & Merino, 2002). Genus Capsicum is a rich source of phenolics (Howard, Talcott, Brenes, & Villalon, 2000). Peppers are also moderate to good sources of flavonoids, which of late have aroused great interest owing to their antioxidant activity (AOX), surpassing that of many other antioxidants (Hasler, 1998). Fresh sweet peppers are also a rich source of ascorbic acid with its content ranging from 76 to 243 mg 100 g1 fresh weight basis (fwb) (Howard, Smith, Wagner, Villalon, & Burns, 1994). Their attractive red colour is due to the profuse synthesis of various carotenoid pigments during ripening. These include oxygenated carotenoids such as capsanthin, capsorubin and crypto-capsin, which are exclusive to this genus and have been shown to be effective free radical scavengers (Matsufuji, Nakamuro, Chino, & Takeda, 1998). The knowledge of the changes, occurring during growth and maturation, holds great significance from both dietary and nutritional point of view. It is therefore, imperative to study the changes in the content of antioxidants as influenced by different genotypes and their maturity stages. There are numerous reports on antioxidant constituents in peppers but reports on AOX per se are limited. The aim of the present work was to evaluate different genotypes of sweet peppers, harvested at different maturity stages for their antioxidant content and total AOX. 2. Material and methods 2.1. Plant material Ten genotypes of sweet pepper were obtained from the green house of Indo-Israel project of Indian Agricultural Research Institute, New Delhi, India. The genotypes selected were originally bred at Holland, Israel, the USA and India (Table 1). All peppers received similar water and fertilizer treatments. Of the 10, seven genotypes were red and three of them yellow at the mature-ripe stage. All the fruits analysed were harvested at the same time but at three
Table 1 Different genotypes of sweet peppers Genotype
Colour at ripe stage
Mazurka (Dutch) Parker (Dutch) Torkel (Dutch) Anupam (India) HA-1195 (Israel) HA-1038 (Israel) Flamingo (the USA) Fiesta (Dutch) Tanvi (India) Golden Summer (India)
Red Red Red Red Red Red Red Yellow Yellow Yellow
successive maturity stages viz. green (fruits showed characteristic green colour), intermediate (50% of the fruit showed transition from green to red/yellow) and finally at full maturity stage (bright red/yellow colour depending on the variety). Three replicates were taken for each cultivar. Each comprised of four fruits (1 kg) harvested from three different plants. Immediately after harvest, the fruits were placed in polyethylene bags and transported under refrigerated conditions to the Division of Post Harvest Technology, IARI within 15 min. Samples were then stored at 20 1C until analysed. Quantitative analysis was carried out for total phenolics, total carotenoids, b-carotene, capsaicin, ascorbic acid and total AOX. The entire analysis was completed within a month of sample collection. 2.2. Total phenolic content Total soluble phenols, in ethanol extracts, were determined with Folin-Ciocalteau reagent using the method of Slinkard and Singelton (1997). Fresh peppers (2 g) were thoroughly crushed and homogenized in 10 ml of 80% ethanol containing 1% HCl. The homogenate was placed in capped test tubes and heated at 60 1C in a water-bath for 60 min. This step helps to complete the extraction of the phenolics as well as to destroy ascorbic acid to a large extent. The reducing property of ascorbic acid has been shown to interfere in estimation of phenols by Folin’s reagent. The extract was cooled and centrifuged at 10,000 rpm for 15 min at 4 1C. The resulting supernatant was collected and the pellet re-extracted and the supernatants were pooled together. The final extract was concentrated in a flash evaporator and the volume reduced to 20 ml. The same extract was used for the estimation of total phenolics and AOX. Results for phenolics were expressed as mg 100 g1 dry/fresh weight catechol equivalent. 2.3. Antioxidant activity AOX was measured using the ferric reducing antioxidant power (FRAP) assay of Benzie and Strain (1996). FRAP reagent consisted of 10 m mol l1 2,4,6-tripyridyl-S-triazine (TPTZ) in 40 m mol l1 HCl, 20 m mol l1 ferric chloride and 300 m mol l1 sodium acetate buffer, pH 3.6 in the ratio of 1:1:10 (v/v). A 100 ml extract was added to 3 ml of FRAP reagent and mixed thoroughly. After standing at ambient temperature (30 1C) for 4 min, absorbance at 593 nm was noted against reagent blank. Calibration was against a standard curve (50–1000 mmol l1 ferrous ion) produced by the addition of freshly prepared ammonium ferrous sulphate. Values were obtained from three replicates and expressed as m mol l1 FRAP g1 dry/fwb. 2.4. Total carotenoids and b-carotene The extraction of carotenoids was carried out according to the method described by Mı´ nguez-Mosquera and Hornero-Me´ndez (1993). A known weight (2 g) of fresh
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sample was extracted with acetone in mortar and pestle. Extractions were repeated until the complete exhaustion of colour (usually 4–5 extractions were enough). All extractions were pooled in a separating funnel and shaken with diethyl ether. A sufficient quantity of 10% NaCl was added at the end to facilitate separation of the two phases. Aqueous phase was discarded. The lipophilic phase was washed with 100 ml of an anhydrous Na2SO4 (2%) solution to remove all the remaining water. It was saponified with the addition of 40 ml of 10% KOH in methanol and shaken vigorously before being left in a dark place for 1 h. After addition of water, the pigments were subsequently extracted with diethyl ether, evaporated in a rotary evaporator and then made up to 25 ml with acetone. One millilitre aliquot of this solution was centrifuged at 12,000 rpm and stored at 20 1C until analysed. Losses occurring during the process were monitored with the use of all-transb-apo-80 -carotenal as internal standard. All analysis was carried out in triplicate. Because of nonavailability of standards for different carotenoids, total carotenoids were estimated by taking the absorbance of extracts at 450 nm (Ranganna, 1986). However, the separation and quantification of b-carotene was carried out using C-18 reverse-phase column and binary gradient elution system (acetone-H2O, 75:25) initially maintained for 5 min, changing linearly to 95:5 in 5 min and kept for 10 min. The flow rate was 1.5 ml min1, and the sample injection volume was 20 ml. At the end of analysis the column was washed with acetone for 3 min and conditioned with the initial proportion for 10 min. Detection of b-carotene was monitored at 450 nm (e1%cm ¼ 2560 in hexane). The final results were expressed as mg 100 g1 dry/fresh weight Capsicum tissue. 2.5. Capsaicin Capsaicin content in the samples was estimated by spectrophotometric measurement of the blue coloured component formed as a result of reduction of phosphomolybdic acid to lower acids of molybdenum (Sadasivam & Manikkam, 1992). Two grams of fresh sample was extracted with 10 ml of dry acetone using pestle and mortar. The extract was centrifuged at 10,000 rpm for 10 min and 1 ml of supernatant was pipetted into a test tube and evaporated to dryness in a hot water-bath. The residue was then dissolved in 0.4 ml of NaOH solution and 3 ml of 3% phosphomolybdic acid. The contents were shaken and allowed to stand for 1 h. The solution was filtered to remove any floating debris and centrifuged at 5000 rpm for 15 min. Absorbance was measured for the clear blue solution, thus obtained, at 650 nm using reagent blank (5 ml of 0.4% NaOH+3 ml of 3% phosphomolybdic acid). Capsaicin content calculated from the standard curve was expressed as mg 100 g1 on dry/fwb. 2.6. Ascorbic acid content Ascorbic acid was quantitatively determined according to 2,6-dichlorophenolindophenol-dye method as described
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by Jones and Hughes (1983) with slight modifications. The ascorbic acid in 10 g of fresh sample was extracted by grinding with a small amount of acid-washed quartz sand and 3% meta-phosphoric acid (v/v). The extract volume was made up to 100 ml, mixed and centrifuged at 3000 g for 15 min at room temperature. Ten milliliters were titrated against standard 2,6-dichlorophenolindophenol dye, which was already standardized against standard ascorbic acid. Results were expressed on mg 100 g1 dry/fwb. 2.7. Statistical analysis Data was analysed using a 3 10 factorial design with maturity stages and genotypes as factors. Duncan’s Multiple Range Test was used to determine significant differences. Significance was determined at Po0:05. All data were reported as mean7standard error of three replications. The computer program employed was MSTAT-C. 3. Results and discussion 3.1. Genotype effects on total phenolic content and antioxidant activity The established health benefits of phenolics, due to their free radical scavenging activities in vitro and in vivo biological systems (Powels & Ness, 1996) necessitates their quantification in foods. There is world wide interest to identify genotypes with enhanced levels of polyphenolics for targeting increased functional properties in foods. Nutritionists are also prompted to include them in the normal dietary compositional tables of fruits and vegetables. In general, data on changes in antioxidant constituents are usually expressed on fwb and expression on dry matter is ignored. Therefore it becomes necessary to establish comparison on dry weight basis (dwb) in order to ascertain whether the obtained values are due to moisture loss or metabolism effects (Raffo et al., 2002). Keeping this in view, all the data in the text has been expressed especially on dwb. However, to adequately reflect the nutritional values of the fresh produce, the data on fwb has also been included wherever necessary. Total phenolic content was measured by using Folin’s reagent. Although, it overestimates the total phenolics due to interfering compounds such as ascorbic acid, it is so far the only single and widely used method for estimating total phenols. However, necessary corrections were employed for ascorbic acid interference, as described in materials and methods. Sweet peppers are an important source of total phenols, which are mainly localized in the peels (Marin, Ferreres, Tomas-Barberan, & Gil, 2004). The results when described on dwb indicated that total phenolic content in the different genotypes of green sweet peppers ranged from as low as 186 mg 100 g1 in Tanvi to 1122 mg 100 g1 in Flamingo, depicting a 6fold variation between genotypes (Fig. 1). The content in red peppers varied from 323 mg 100 g1 in Torkel to 852 mg 100 g1 in Flamingo, depicting
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Fig. 1. Total phenolic content in sweet peppers during different maturity stages. Green stage means7S.E. (n ¼ 3). The same letters above the bars indicate no significant differences.
a 2.6fold variation. Flamingo was the single genotype with significantly high levels of phenolics at all the three stages of maturity (Fig. 1). Apart from Flamingo, yellow sweet pepper Golden Summer also had significantly high phenolic content of 720.5 mg 100 g1 at the yellow stage. However, during maturity from green to red stage, a declining trend was observed in four genotypes viz., Parker, Torkel, HA-1038 and Flamingo whereas Mazurka, Anupam and HA-1195 showed no significant differences. Yellow cultivars namely, Fiesta, Tanvi and Golden Summer exhibited an increasing trend. Total phenolic content when expressed on fwb increased during maturity from green to red/yellow ripe stage in all the genotypes. The values ranged from as low as 12.5 mg 100 g1 in Tanvi to as high as 66.25 mg 100 g1 in Flamingo and in rest of the genotypes a range of 20–40 mg 100 g1 was observed. The values observed here in our cultivars were considerably low in comparison to those reported by Howard et al. (2000) in Capsicum spp. Varietal differences, plant part used (with seeds) may have accounted for higher values. Seeds from various plant sources have been shown to be contributing significantly towards high total phenolic content (Velioglu, Mazza, Gao, & Oomah, 1998). Our results on changes during maturity are in line with Howard et al. (2000) who observed an increasing trend in the total phenolics during maturity in majority of Capsicum cultivars. On the contrary, Marin et al. (2004) recently have shown a marginal decrease in total phenolic content during maturity from green to red stage. Plant age and maturity are the major determinants of variation in phenolic content (Vallejo, Garcı´ a-Viguera, & Toma´sBarbera´n, 2003). Sweet peppers contain a very rich polyphenol pattern, which includes hydroxycinnmates, flavonols and flavones (Marin et al., 2004). Thus for a clear understanding of metabolic changes in phenolics during maturation it is necessary to characterize the phenolic profile.
, intermediate stage
, red/yellow stage
. Data are
AOX is an important parameter to establish the health functionality of a food product and there are many methods employed for its measurement (Kaur et al., 2001). The AOX of the different pepper extracts was measured in terms of iron reducing property, using the FRAP assay. In spite of its limitations, FRAP is still by and large the most useful, inexpensive and rapid method for screening large samples. On dwb, the AOX ranged from 47.9 m mol l1 g1 in Fiesta to 293.2 m mol l1 g1 in Flamingo at the green stage and from 54.3 m mol l1 g1 in Fiesta to 376.5 m mol l1 g1 in Flamingo at the red stage (Fig. 2). This showed a 6fold variation in AOX among genotypes during maturation from green to red-ripe stage. Genotype Flamingo, among the red types and Golden Summer among the yellow types had the highest AOX. Other red genotypes namely, Mazurka, Anupam, HA-1195 and HA-1038 also had appreciably high AOX in the range of 100.9–254.4 m mol l1 g1. AOX in the sweet peppers increased with maturation in most of the genotypes the changes being more significant (Po0:05) only in HA-1195, Flamingo and Golden Summer (Fig. 2). The genotype x maturity interaction was significant for both phenolics and AOX. This signifies that both genotypes and maturity stages play a crucial role in determining the content of antioxidant constituents (Russo & Howard, 2002; Vallejo et al., 2003). A significant decline in AOX with maturity was also observed in genotypes Torkel and Tanvi. Reports on AOX in peppers are limited (Howard et al., 2000; Lee, Howard, & Villalon, 1995). In a recent study, using FRAP assay, Ou, Huang, Hampschwoodwill, Flanagan, and Deemer (2002) examined 13 potential vegetables for their AOX and ranked red peppers as the first followed by green peppers. The data on AOX when expressed on fwb ranged from 3.2 m mol l1 g1 in Parker to 17.3 m mol l1 g1 in Flamingo at the green stage while the range was 4.8 m mol l1 g1 in Fiesta to 32.0 m mol l1 g1 in Flamingo at their respective ripe yellow and red stages. AOX thus,
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Fig. 2. Total antioxidant activity in sweet peppers during different maturity stages. Green stage means7S.E. (n ¼ 3). The same letters above the bars indicate no significant differences.
increased markedly with maturity. Expression on fwb revealed that there was an increase of 1.30–1.95fold in most of the genotypes except Torkel and Tanvi which showed a marginal increase. Enhanced AOX at the red stage reflects the nutritional importance of consuming the peppers fresh at the ripe red/yellow stage. The FRAP assay was also extended to determine the AOX in the lipophilic extracts (carotenoids), but no activity was observed in these fractions. In fact this assay allowed the overall estimation of water-soluble compounds influencing the total AOX. Compounds not readily soluble in this solvent, specifically carotenoids, were logically excluded in their contribution to AOX (Pulido, Bravo, & Saura-Calixto, 2000). It is impossible to measure total AOX using only a single assay. So far only a few methods have been developed to measure lipophilic AOX (Huang, Ou, Hampsch-Woodill, Flanagan, & Deemer, 2002; Pulido et al., 2000) but these have their own limitations in respect of availability of reagents and reproducibility of results. It is because of these facts it is not a trivial task to accurately measure their AOX in vitro (Ou et al., 2001). Therefore the lipophilic nutrients are usually ignored in many investigations. Lipophilic components are as important as phenolic and ascorbic components in AOX assays as these are more bioavailable. Though, we have excluded the contributions of carotenoids towards AOX, it is pertinent to point out that sweet peppers are also a rich source of hydrophilic antioxidants like ascorbic acid, and flavonoids and have a rich polyphenolic pattern (Marin et al., 2004). 3.1.1. Relationship between FRAP and phenolics Comparison of the total phenolics and AOX when expressed on fwb showed R2 ¼ 0:56 at the green stage and R2 ¼ 0:33 at red stage. However on dwb, it revealed a similar positive correlation at the green stage (R2 40:55). But correlation at the red stage was little better
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, intermediate stage
, red/yellow stage
. Data are
(R2 ¼ 0:45). Such differences could easily be explained on the basis of compositional diversity and presence of polar analytes and their interactions with less polar compounds, influencing AOX. High AOX observed in genotype Flamingo may possibly be attributed to its high phenolic content. Plethora of research findings suggests that genotypes with high phenolic content also have high AOX (Howard et al., 2000; Wang & Lin, 2000). Gazzani, Papetti, Massolini, and Daglia (1998) observed similar response in unfractionated bell pepper juice using a b-carotene-lineolate assay.
3.2. Carotenoid content Peppers are also a good source of carotenoids, which can vary in composition and concentration owing to differences in genetics and maturation (Markus, Daood, Kapitany, & Biacs, 1999; Russo & Howard, 2002). During ripening of sweet peppers the green colour due to chlorophyll and carotenoids such as lutein disappear with the synthesis of chromoplast pigments (Hornero-Me´ndez, Guevara, & Mı´ nguez-Mosquera, 2000). Total carotenoid content (dwb) ranged from 5.7 mg 100 g1 in Flamingo to 43.2 mg 100 g1 in Anupam at the green stage. There was sharp increase in carotenoid content with maturity and at the red stage Anupam showed the highest content of 132.5 mg 100 g1 while Flamingo had the least (11.4 mg 100 g1) (Fig. 3). Thus with advancing maturity a maximum of 3fold variation was observed in genotype Anupam. However, comparison between genotypes revealed a maximum variation of 11folds between Anupam and Flamingo at the red stage. These values are low in comparison to 690–1320 mg 100 g1 dwb reported in 5 red Capsicum fruits by Hornero-Me´ndez et al. (2000). Data when expressed on fwb revealed the total carotenoid content ranging from 0.34 mg 100 g1 in Flamingo to
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Fig. 3. Total carotenoids in sweet peppers during different maturity stages. Green stage means7S.E. (n ¼ 3). The same letters above the bars indicate no significant differences.
, intermediate stage
, red/yellow stage
. Data are
Fig. 4. b-carotene content in sweet peppers during different maturity stages. Green stage means7S.E. (n ¼ 3). The same letters above the bars indicate no significant differences.
, intermediate stage
, red/yellow stage
. Data are
3.28 mg 100 g1 in Anupam while rest of the genotypes falling within a range of 1.5–2.5 mg 100 g1. b-carotene content (dwb) ranged from a lowest of 474 mg 100 g1 in Flamingo to 3108 mg 100 g1 in Parker at the green stage. At the red stage it ranged from 932 mg 100 g1 in HA-1038 to 6244 mg 100 g1 in HA-1195. Appreciably, high content (3669–5989 mg 100 g1) was also observed in Parker, Flamingo, Anupam and Torkel at the red stage. Yellow genotypes, namely Fiesta, Tanvi and Golden Summer had low content ranging from 1400 to 2200 mg 100 g1. b-carotene content increased with advancing maturity. Significant differences in b-carotene content (Po0:05) with respect to different maturity stages were observed in genotypes, Anupam, Torkel, HA-1195, Flamingo and Golden Summer (Fig. 4). This is in line with previous reports quantifying pepper carotenoids as a function of maturity (Davies, Matthews, & Kirk, 1970;
Howard et al., 2000). Dramatic increase (13fold) in b-carotene content was observed in Flamingo, during maturity (Fig. 4). This trend was observed when the values were expressed both on fwb and dwb. The values when expressed on fwb were within the range of 0.094–0.694 mg 100 g1. The genotype x maturity interaction was significant for carotenoids as well, underlining that both genotypes and maturity are determinants of the content of antioxidant constituents in sweet peppers. In the recent report by Marin et al. (2004), b-carotene content has been observed to be 1.7–4.3 mg 100 g1 fwb in sweet pepper cv. Vergasa. However, Daood, Vinkler, Markus, Hebshi, and Biacs (1996) have reported a similar increase in b-carotene content (dwb) at the last stages of ripening. Besides, the authors have also highlighted the significant differences found between the different cultivars with regard to the antioxidant vitamin content.
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3.3. Capsaicin
3.4. Ascorbic acid
Capsaicin (8-methyl-n-vanillyl-6-non-enamide) is the dominant pungency principle unique to the genus, Capsicum, which imparts flavour and also has therapeutic uses for its anticarcinogenic properties (Surh & Lee, 1996). The 10 genotypes analysed had capsaicin content varying from 776–1440 mg 100 g1 at green stage to 277–1529 mg 100 g1 dwb at the mature red stage. Capsaicin content decreased with maturity except for two genotypes, HA1195 and Anupam, showing 1529 and 833 mg 100 g1, respectively, at the red stage. At the green stage, Flamingo (1440 mg 100 g1), Mazurka (1416 mg 100 g1) and Golden Summer (1369 mg 100 g1) were superior with regard to their capsaicin content (Fig. 5). Genotype HA-1195 had 5.5 times higher capsaicin concentration than the yellow sweet pepper Tanvi, which contained the lowest at the mature stage. However, it was interesting to note that though there were drastic differences in capsaicin levels between genotypes, the magnitude of increase/decrease with maturity within a genotype was only 1.1–1.3fold. The increase or decrease in capsaicin content with maturity as observed in different genotypes may be attributed to inherent variation in the levels of peroxidase enzymes in different sweet pepper cultivars (Estrada, Bernal, Diaz, Pomar, & Merino, 2000). The content on fwb ranged from 25–100 mg 100 g1 to 25–110 mg 100 g1at the green and red stages, respectively. The pungent spice red pepper contains very high amounts of capsaicin ranging from 214 to 1166 mg g1 dwb (Gnayfeed, Daood, Biacs, & Alcaraz, 2001) but the variations observed during ripening in our study are in conformity with their reports. However, the sweet pepper genotypes analysed in the present study contains low content of capsaicin, which contributes to their characteristic flavour and also makes them suitable for culinary preparation.
Ascorbic acid content was found to vary significantly (Po0:05) among sweet pepper genotypes harvested during different maturity stages. The content on dwb varied from 980 mg 100 g1 in Mazurka to 3030 mg 100 g1 in HA-1038 at the green stage. At the red stage it ranged from 647 to 2135 mg 100 g1 in the same cultivars (Fig. 6). This depicted a 3fold variation in ascorbic acid content among genotypes. At the green stage, genotypes HA-1038 (3030 mg 100 g1) and Flamingo (2572 mg 100 g1) had significantly higher content than the rest (Fig. 6). HA-1038 also had the highest content (2135 mg 100 g1) at the red stage followed by HA-1195, Flamingo and Golden Summer. Ascorbic acid content showed a declining trend with advancing maturity. However, values when expressed on fwb showed a reverse trend. At the green stage the content raged from 58.8–200 mg 100 g1 and 64–220 mg 100 g1 at the red stage. This variation could be accounted to the changes in the moisture content in peppers during different maturity stages (Table 2). It is difficult to compare the results of different workers because the changes during different maturity stages have been expressed on fwb instead of dwb (Howard et al., 2000; Marin et al., 2004). Therefore, it is important that for evaluation of changes occurring during maturity within a genotype, the antioxidant content calculations be based on dry matter as it will clearly establish whether the obtained results are due to metabolic effects or otherwise. With regard to RDA, a 100 g serving of fresh sweet peppers could supply more than 100% RDA (60 mg day1) for vitamin C. However, red genotypes, HA-1038, HA1195 and Flamingo and yellow pepper, Golden Summer were found to be exceptionally good as they exceeded 200% of RDA.
Fig. 5. Capsaicin content in sweet peppers during different maturity stages. Green stage means7S.E. (n ¼ 3). The same letters above the bars indicate no significant differences.
, intermediate stage
, red/yellow stage
. Data are
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Fig. 6. Ascorbic acid content in sweet peppers during different maturity stages. Green stage means7S.E. (n ¼ 3). The same letters above the bars indicate no significant differences.
Table 2 Moisture content (g/100 g) in sweet peppers during different maturity stages Genotypes
Green
Intermediate
Red/yellow
Mazurka Parker Torkel Anupam HA-1195 HA-1038 Flamingo Fiesta Tanvi Golden Summer
94.00 94.25 93.60 92.40 93.50 93.40 94.10 92.97 93.30 92.70
91.60 90.15 91.60 90.40 92.90 90.20 92.70 91.40 91.35 91.30
90.00 88.95 88.40 89.80 93.20 89.70 91.50 91.10 91.00 91.50
LSD(0.05). Maturity stage (A) 0.355. Genotypes (B) 0.355. A B 0.712.
4. Conclusions Significant variation in total phenols, AOX, carotenoids, ascorbic acid and capsaicin content between sweet pepper genotypes and maturity stages, indicates that the potential efficacy of antioxidants vary considerably with both genotypes as well maturity stages. Nutritionally, sweet peppers at the red stage are a good source of mixture of antioxidants including ascorbic acid, carotenoids and polyphenols. Genotypes, HA-1195, Flamingo and Anupam from Israel, the USA and India, respectively, have rich dietary composition, which may offer potential health benefits. References Benzie, I. E. F., & Strain, J. J. (1996). The ferric reducing ability of plasma (FRAP) as a measure of antioxidant power: the FRAP assay. Analytical Biochemistry, 239, 70–76.
, intermediate stage
, red/yellow stage
. Data are
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