Change in the carotenoid and antioxidant content of spice red pepper (paprika) as a function of ripening and some technological factors

Physiological and metabolomic analysis reveals maturity stage-dependent nitrogen regulation of vitamin C content in pepper fruit

Pepper is one of the most vitamin C enriched vegetables worldwide. Although applying nitrogen (N) fertilizer is an important practice for high fruit yield in pepper production, it is still unclear how N application regulates pepper fruit vitamin C anabolism at different maturity stage. To further the understanding, we combined physiological and metabolomic analysis to investigate the fruit vitamin C content (including ascorbic acid (AsA) and dehydroascorbic acid (DHA)), related enzyme activity and non-targeted metabolites of field-grown chili pepper produced under different N levels at mature green and red stages. The results showed that increasing N application reduced AsA content in pepper fruit at both maturity stages, but highly elevated DHA content only at mature green stage. Regardless of N application level, AsA content displayed an increasing trend while DHA content was reduced as pepper fruit maturity advanced, resulting in a higher content of total vitamin C at the mature green stage. The L-galactose pathway, D-galacturonate pathway, and myo-inositol pathway were identified for AsA biosynthesis. The involved precursor metabolites were mainly negatively regulated by increasing N application, and their accumulation increased when pepper fruit developed from green to red stage. Meanwhile, the activities of key enzymes and metabolites in relation to degradation and recycling processes of AsA and DHA were increased or did not change with increasing N application, and they were differently influenced as fruit maturing. As a result, the recommended N application level (250 kg N ha^-1) could maintain relatively high total vitamin C content in pepper fruits without yield loss at both maturity stages. These findings highlight the importance of optimizing N application level to maximize vitamin C content in pepper fruits, and provide a better understanding of the maturity stage-dependent N regulation on vitamin C anabolism.

The Identification and Quantitative Analysis of Unusual Keto-Carotenoids in Ripe Fruits of Maclura tricuspidate and Its Potential as a Valuable Source of Cryptocapsin

Ripe fruits of Maclura tricuspidata (MT) are used as food material and a natural colorant in Korea. Although MT fruits have a deep red color due to carotenoid-like pigments, their chemical nature has not been explored in detail so far. The present study aimed at elucidating the chemical structures and composition of carotenoids in MT fruits and changes at different maturity stages. Two carotenoids from saponified MT fruit extract were isolated using repeated silica gel column chromatography. Based on interpretations of spectroscopic data, these compounds were determined as keto-carotenoids, i.e., capsanthin (3,3'-dihydroxy-β,κ-caroten-6'-one) and cryptocapsin (3'-hydroxy-β,κ-caroten-6'-one), and the contents of individual carotenoids were quantified with HPLC based on calibration curves obtained from authentic standards. The contents of capsanthin and cryptocapsin in the sample of saponified MT fruits were 57.65 ± 1.97 µg/g and 171.66 ± 4.85 μg/g as dry weight base (dw). The majority of these keto-carotenoids in the MT fruits were present in esterified forms with lauric, myristic or palmitic acid rather than in their free forms. The results also showed that esterification of these compounds occurred starting from early stage (yellow-brownish stage) of maturation. Considering the high cryptocapsin content, MT fruits can be applied as a potentially valuable source of cryptocapsin for food and medicinal application as well as a source of provitamin A.

Freeze-Dried Powder of Fermented Chili Paste-New Approach to Cured Salami Production

Fermented chili powders were obtained through the freeze-drying of fermented chili pastes and used as a condiment, acidifier, antioxidant, colorant, and microbial starter carrier in fermented salami production. Fermented chili powders were examined regarding carbohydrates, organic acids, vitamin C, phenolic compounds, carotenoids, and aroma profile. High concentrations of lactic (10.57-12.20%) and acetic acids (3.39-4.10%) were recorded. Vitamin C content was identified in the range of 398-1107 mg/100 g, with maximum values for C. annuum cv. Cayenne chili powder. Phenolic compounds showed values between 302-771 mg/100 g. Total carotenoid content was identified between 544-2462 µg/g, with high concentrations of capsanthin esters. Aroma profile analysis evidenced specific compounds (1-hexanol, 2-hexanol, hexenal, E-2-hexenal) with sensory importance and a more complex spectrum for Capsicum chinense cultivar. Plant-specific lactic acid bacteria showed dominance both in fermented chili paste, chili powder, and salami. Lactic and acetic acids from the fermented chili powder reduced the pH of the filling immediately, having a stabilizing effect on the meat. Nor molds or pathogens were identified in outer limits. Based on these results, fermented chili powders could be used as starter carriers in the production of fermented meat products for exceptional sensory properties and food safety management.

Mitochondrial protein expression during sweet pepper (Capsicum annuum L.) fruit ripening: iTRAQ-based proteomic analysis and role of cytochrome c oxidase

The physiological process of fruit ripening is associated with the late developmental stages of plants in which mitochondrial organelles play an important role in the final success of this whole process. Thus, an isobaric tag for relative and absolute quantification (iTRAQ)-based analysis was used to quantify the mitochondrial proteome in pepper fruits in this study. Analysis of both green and red pepper fruits identified a total of 2284 proteins, of which 692 were found to be significantly more abundant in unripe green fruits as compared to red fruits, while 497 showed lower levels as the ripening process proceeded. Of the total number of proteins identified, 2253 (98,6%) were found to share orthologs with Arabidopsis thaliana. Proteomic analysis identified 163 proteins which were categorized as cell components, the major part assigned to cellular, intracellular space and other subcellular locations such as cytosol, plastids and, to a lesser extent, to mitochondria. Of the 224 mitochondrial proteins detected in pepper fruits, 78 and 48 were more abundant in green and red fruits, respectively. The majority of these proteins which displayed differential abundance in both fruit types were involved in the mitochondrial electron transport chain (mETC) and the tricarboxylic acid (TCA) cycle. The abundance levels of the proteins from both pathways were higher in green fruits, except for cytochrome c (CYC2), whose abundance was significantly higher in red fruits. We also investigated cytochrome c oxidase (COX) activity during pepper fruit ripening, as well as in the presence of molecules such as nitric oxide (NO) and hydrogen peroxide (H₂O₂), which promote thiol-based oxidative post-translational modifications (oxiPTMs). Thus, with the aid of in vitro assays, cytochrome c oxidase (COX) activity was found to be potentially inhibited by the PTMs nitration, S-nitrosation and carbonylation. According to protein abundance data, the final segment of the mETC appears to be a crucial locus with regard to fruit ripening, but also because in this location the biosynthesis of ascorbate, an antioxidant which plays a major role in the metabolism of pepper fruits, occurs.

Pilot-Scale Optimization of Supercritical CO2 Extraction of Dry Paprika Capsicum annuum: Influence of Operational Conditions and Storage on Extract Composition

Supercritical carbon dioxide extraction was used to extract carotenoids from dry paprika Capsicum annuum. Studies regarding the effect of process parameters, including pressure (25–45 MPa), temperature (40–60 °C), and time (10–110 min), were carried out using response surface methodology. It was found that under optimal conditions (pressure of 45 MPa, temperature of 50 °C, and time of 74 min), the extract yield was 10.05%, and the total content of carotenoids in the extract was 4.21%, in good agreement with the predicted values (10.24% and 4.24%, respectively). Composition analysis showed that paprika extract mainly consisted of linoleic acid. There was no significant difference between the fatty acid content of the extracts obtained by SC-CO₂ extraction and n-hexane Soxhlet extraction. For functional purposes, the effect of storage conditions and time on the quality of paprika extract was also specified.

The retention and bioavailability of phytochemicals in the manufacturing of baked snacks

There is a growing body of evidence supporting the role that phytochemicals play in reducing the risk of various chronic diseases. Although there has been a rise in health products marketed as being "supergrains," "superfood," or advertising their abundance in antioxidants, these food items are often limited to powdered blends, dried fruit, nuts, or seeds, rarely intercepting the market of baked snacks. This is in part due to the still limited understanding of the impact that different industrial processes have on phytochemicals in a complex food matrix and their corresponding bioavailability. This review brings together the current data on how various industrial dehydration processes influence the retention and bioaccessibility of phytochemicals in baked snacks. It considers the interplay of molecules in an intricate snack matrix, limitations of conventional technologies, and constraints with consumer acceptance preventing wider utilization of novel technologies. Furthermore, the review takes a holistic approach, encompassing each stage of production-discussing the potential for inclusion of by-products to promote a circular economy and the proposal for a shift in agriculture toward biofortification or tailored growing of crops for their nutritional and post-harvest attributes.

Influence of the Phenological Stage and Harvest Date on the Bioactive Compounds Content of Green Pepper Fruit

Green pepper fruit is often consumed before it is completely ripe. However, the influence of the phenological stage in which the green pepper is consumed as a potential influencing factor in its bioactive compounds content and antioxidant capacity remains unknown. In addition, no literature is available concerning the bioactive compounds changes in 'Lamuyo' green peppers along its developmental and growth cycle. For this, two different approaches have been carried out, one using twelve different phenological stages (S1 to S12), and in the other, seven different harvest dates (from 27 February to 20 April). Moreover, bioactive compounds changes during 21 days of postharvest storage at 8 °C were investigated. In this study, bioactive compounds (ascorbic acid, dehydroascorbic acid, and total phenolic content) and the total hydrophilic and lipophilic (TAA-H and TAA-L) antioxidant activity were analysed. In addition, total soluble solids, total acidity, individual sugars, and organic acids were determined. Vitamin C levels increased along the phenological stages and harvest dates due to significant increases in ascorbic and dehydroascorbic acid levels. Our results show that the total phenol content decreases as vegetables develop and subsequently increases both as ripening begins and by the last harvest date. Furthermore, TAA-H was also greater by the phenological stage S12 and the 20 April harvest date. In conclusion, the phenological stage and harvest date are key factors that significantly influence the bioactive compounds of green peppers, and those that appear by S12 and 20 April could be more beneficial to health.

Structural and functional features of phytoene synthase isoforms PSY1 and PSY2 in pepper Capsicum annuum L. cultivars

The fruits of various pepper cultivars are characterized by a different color, which is determined by the pigment ratio; carotenoids dominate in ripe fruits, while chlorophylls, in immature fruits. A key regulator of carotenoid biosynthesis is the phytoene synthase encoded by the PSY gene. The Capsicum annuum genome contains two isoforms of this enzyme, localized in leaf (PSY2) and fruit (PSY1) plastids. In this work, the complete PSY1 and PSY2 genes were identified in nine C. annuum cultivars, which differ in ripe fruit color. PSY1 and PSY2 sequence variability was 2.43 % (69 SNPs) and 1.21 % (36 SNPs). The most variable were PSY1 proteins of the cultivars 'Maria' (red-fruited) and 'Sladkij shokolad' (red-brown-fruited). All identified PSY1 and PSY2 homologs contained the phytoene synthase domain HH-IPPS and the transit peptide. In the PSY1 and PSY2 HH-IPPS domains, functionally significant sites were determined. For all accessions studied, the active sites (YAKTF and RAYV), aspartate-rich substrate-Mg²⁺-binding sites (DELVD and DVGED), and other functional residues were shown to be conserved. Transit peptides were more variable, and their similarity in the PSY1 and PSY2 proteins did not exceed 78.68 %. According to the biochemical data obtained, the largest amounts of chlorophylls and carotenoids across the cultivars studied were detected in immature and ripe fruits of the cv. 'Sladkij shokolad' and 'Shokoladnyj'. Also, ripe fruits of the cv. 'Nesozrevayuschij' (green-fruited) were marked by significant chlorophyll content, but a minimum of carotenoids. The PSY1 and PSY2 expression patterns were determined in the fruit pericarp at three ripening stages in 'Zheltyj buket', 'Sladkij shokolad', 'Karmin' and 'Nesozrevayuschij', which have different ripe fruit colors: yellow, red-brown, dark red and green, respectively. In the leaves of the cultivars studied, PSY1 expression levels varied significantly. All cultivars were characterized by increased PSY1 transcription as the fruit ripened; the maximum transcription level was found in the ripe fruit of 'Sladkij shokolad', and the lowest, in 'Nesozrevayuschij'. PSY2 transcripts were detected not only in the leaves and immature fruits, but also in ripe fruits. Assessment of a possible correlation of PSY1 and PSY2 transcription with carotenoid and chlorophyll content revealed a direct relationship between PSY1 expression level and carotenoid pigmentation during fruit ripening. It has been suggested that the absence of a typical pericarp pigmentation pattern in 'Nesozrevayuschij' may be associated with impaired chromoplast formation.

In vitro α-amylase and α-glucosidase enzyme inhibition and antioxidant activity by capsaicin and piperine from Capsicum chinense and Piper nigrum fruits

In the present study, α-amylase and α-glucosidase inhibitory effect and antioxidant activity of capsaicin and piperine from the ethanolic extract of Capsicum chinense (EECch) and Piper nigrum (EEPn) fruits were investigated. Results revealed that EECch exhibited the highest phenolic (154 mg GAE/100 g of tissue) and flavonoid content (75 mg RtE/100 g of tissue) in comparison with EEPn. The predominant compound detected in EECch and EEPn by GC-EIMS analysis was the capsaicin and piperine, respectively. The capsaicin and piperine showed the highest α-amylase and α-glucosidase inhibitory effect and antioxidant activity rather than extracts. The EEPn (IC₅₀= 216 µg/mL) and piperine (IC₅₀= 105 µg/mL) present a highest α-amylase inhibitory effect, while the EECch (IC₅₀= 225 µg/mL) and capsaicin (IC₅₀= 117 µg/mL) showed highest anti-α-glucosidase activity. Molecular docking established that capsaicin and piperine bind at the α-glucosidase and α-amylase through hydrophobic interactions, hydrogen bond, and charge interactions with amino acid residues. The enzyme inhibitory activity and antioxidant properties exhibited by EECch and EEPn could be attributed to the capsaicin and piperine content and other compounds present such as phenolic compounds and flavonoids. These fruits are potential sources of natural antioxidant agents and α-amylase and α-glucosidase inhibitors.

A Maturity Estimation of Bell Pepper (Capsicum annuum L.) by Artificial Vision System for Quality Control

Sweet bell peppers are a Solanaceous fruit belonging to the Capsicum annuum L. species whose consumption is popular in world gastronomy due to its wide variety of colors (ranging green, yellow, orange, red, and purple), shapes, and sizes and the absence of spicy flavor. In addition, these fruits have a characteristic flavor and nutritional attributes that include ascorbic acid, polyphenols, and carotenoids. A quality criterion for the harvest of this fruit is maturity; this attribute is visually determined by the consumer when verifying the color of the fruit’s pericarp. The present work proposes an artificial vision system that automatically describes ripeness levels of the bell pepper and compares the Fuzzy logic (FL) and Neuronal Networks for the classification stage. In this investigation, maturity stages of bell peppers were referenced by measuring total soluble solids (TSS), ° Brix, using refractometry. The proposed method was integrated in four stages. The first one consists in the image acquisition of five views using the Raspberry Pi 5 Megapixel camera. The second one is the segmentation of acquired image samples, where background and noise are removed from each image. The third phase is the segmentation of the regions of interest (green, yellow, orange and red) using the connect components algorithm to select areas. The last phase is the classification, which outputs the maturity stage. The classificatory was designed using Matlab’s Fuzzy Logic Toolbox and Deep Learning Toolbox. Its implementation was carried out onto Raspberry Pi platform. It tested the maturity classifier models using neural networks (RBF-ANN) and fuzzy logic models (ANFIS) with an accuracy of 100% and 88%, respectively. Finally, it was constructed with a content of ° Brix prediction model with small improvements regarding the state of art.

A high-throughput platform for interpretation of metabolite profile data from pepper (Capsicum) fruits of 13 phenotypes associated with different fruit maturity states

Nowadays, novel tools have been developed for efficient analysis and visualization of large-scale metabolite profile data associated with metabolic pathways. A high-throughput platform using PathVisio 3 combined with multivariate analysis is proposed for the first time. Additionally, this is the first analysis of the relationships among terpenoids monoterpene, sesquiterpene, triterpene, and tetraterpene during pepper fruit ripening, and their changes. This platform was successfully applied to interpret large-scale data related to 131 metabolites from mature and immature fruits of 13 pepper phenotypes. The carotenoid-derived volatiles, such as dihydroactinidiolide and β-ionone were closely correlated with carotenoids, indicating that the synthesis and degradation of carotenoids occurred in pepper fruit mature stage. Using PathVisio 3, the metabolic changes in pathway could be presented quickly, revealing the accumulation of stress-related metabolites, such as proline, capsaicin, and phenylalanine, in the mature stage. This approach could provide useful information about comprehensive biochemical regulation of fruit ripening.

Influence of Postharvest Temperatures on Carotenoid Biosynthesis and Phytochemicals in Mature Green Chili (Capsicum annuum L.)

An intense red color appearance in hot chili is what industry commonly demands. The harvested mature green “Takanotsume” chili, a popular cultivar in Japan, incubated at 20 and 30 °C is investigated. At 30 °C, the chili rapidly degraded chlorophylls and obtained an intense red color, but presented an orange–red color at 20 °C. The sample showed higher carotenoid accumulations at 30 °C, along with significantly upregulated carotenoid biosynthesis-related genes—phytoene synthase (Psy), lycopene-β-cyclase (Lcyb), β-carotene hydroxylase (CrtZ), and capsanthin/capsorubin synthase (Ccs)—during the experiment. While the expression of the Ccs gene was reduced, there was a 5.5-fold upregulation of the Psy gene at the end of incubation. At 20 °C, the Psy gene was downregulated. These observations suggest that the expression of individual genes is temperature-dependent, and these would affect specific carotenoid compounds. The antioxidant capacity (2,2-diphenyl-1-picrylhydrazyl; DPPH and ferric-reducing antioxidant power; FRAP) values had no difference between temperatures; the higher content of total phenolics and vitamin C presented in the chili at 30 °C probably corresponds to the advanced ripening process. Thus, 30 °C is the recommended incubation temperature for mature green chili to achieve the industry-demanded intense red color and high accumulation of phytochemicals.

Color Development and Phytochemical Changes in Mature Green Chili (Capsicum annuum L.) Exposed to Red and Blue Light-Emitting Diodes

Exposure of mature green "Takanotsume" chili fruit to blue and red light-emitting diodes (LEDs) was investigated. The red LED accelerated the red color development of chili as indicated by higher a* and chroma values, as well as lower hue angle and total chlorophyll compared to the blue LED and darkness (control). These were linked to increases in β-carotene, free-capsanthin, and total carotenoids. The carotenoid biosynthesis-related genes, lycopene-β-cyclase (Lcyb), β-carotene hydroxylase (CrtZ), and capsanthin/capsolubin synthase (Ccs), were up-regulated by the red LED after 2 days of the experiment. The blue LED was more effective in increasing the expression of the phytoene synthase (Psy) gene at day 1 of experiment. The total phenolic, vitamin C content, and antioxidant capacity were also higher in the blue LED-treated chili. Results suggest that the responses of each carotenoid-related gene to the light wavelengths and the accumulation of phytochemicals are specific characteristics of this chili cultivar.

Application of encapsulated natural bioactive compounds from red pepper waste in yogurt

Aim: The aim of this study was to encapsulate red pepper waste (RPW) bioactives and monitor their stability in yogurt.Methods: RPW extract was encapsulated in whey protein using spray and freeze-drying techniques. Physicochemical characteristics of encapsulates were evaluated, and better encapsulates were used to develop functional yogurt. Retention of bioactives was followed over 21 days of storage, and sensory analyses were assessed.Results: Freeze-dried encapsulates (FDE) showed better characteristics like water activity, moisture content, solubility, flowing and colour properties, and, therefore, incorporated in yogurt. Yogurt with FDE successfully retained carotenoids (71.43%) and caused increasing of polyphenol retention (up to 123.73%). This yogurt exhibited higher sensory and general acceptability scores compared to control sample. The fortification of yogurts had a positive influence on maintaining the initial number of lactic acid bacteria during storage.Conclusion: Freeze drying and utilisation of pepper waste are efficient for functional food development, with improved nutritional, colour and bioactive properties.

Determination of HPLC-UV Fingerprints of Spanish Paprika (Capsicum annuum L.) for Its Classification by Linear Discriminant Analysis

The development of a simple HPLC-UV method towards the evaluation of Spanish paprika's phenolic profile and their discrimination based on the former is reported herein. The approach is based on C18 reversed-phase chromatography to generate characteristic fingerprints, in combination with linear discriminant analysis (LDA) to achieve their classification. To this aim, chromatographic conditions were optimized so as to achieve the separation of major phenolic compounds already identified in paprika. Paprika samples were subjected to a sample extraction stage by sonication and centrifugation; extracting procedure and conditions were optimized to maximize the generation of enough discriminant fingerprints. Finally, chromatograms were baseline corrected, compressed employing fast Fourier transform (FFT), and then analyzed by means of principal component analysis (PCA) and LDA to carry out the classification of paprika samples. Under the developed procedure, a total of 96 paprika samples were analyzed, achieving a classification rate of 100% for the test subset (n = 25).

Characterization of the pigment fraction in sweet bell peppers (Capsicum annuum L.) harvested at green and overripe yellow and red stages by offline multidimensional convergence chromatography/liquid chromatography-mass spectrometry

Offline multidimensional supercritical fluid chromatography combined with reversed-phase liquid chromatography was employed for the carotenoid and chlorophyll characterization in different sweet bell peppers (Capsicum annuum L.) for the first time. The first dimension consisted of an Acquity HSS C18 SB (100 × 3 mm id, 1.8 μm particles) column operated with a supercritical mobile phase in an ultra-performance convergence chromatography system, whereas the second dimension was performed in reversed-phase mode with a C30 (250 × 4.6 mm id, 3.0 μm particles) stationary phase combined with photodiode array and mass spectrometry detection. This approach allowed the determination of 115 different compounds belonging to chlorophylls, free xanthophylls, free carotenes, xanthophyll monoesters, and xanthophyll diesters, and proved to be a significant improvement in the pigments determination compared to the conventional one-dimensional liquid chromatography approach so far applied to the carotenoid analysis in the studied species. Moreover, the present study also aimed to investigate and to compare the carotenoid stability and composition in overripe yellow and red bell peppers collected directly from the plant, thus also evaluating whether biochemical changes are linked to carotenoid degradation in the nonclimacteric investigated fruits, for the first time.

Metabolite Profiling of Peppers of Various Colors Reveals Relationships Between Tocopherol, Carotenoid, and Phytosterol Content

Peppers are widely consumed in Korea; the varietal development of peppers with increased content of beneficial plant metabolites is, therefore, of considerable interest. This requires a comprehensive understanding of the metabolic profile of pepper plants and the factors affecting this profile. To this end, we determined the content of various metabolites, such as hydrophilic and lipophilic compounds, phenolic acids, carotenoids, and capsaicinoids in peppers of various colors (green, red, pale green, and violet peppers) and in a high-pungency (green) pepper. We also performed principal component analysis (PCA), Pearson's correlation analysis, and hierarchical clustering analysis (HCA) to determine the relationships among these metabolites in peppers. PCA results indicated no significant variances among the 3 sample replicates. The HCA showed correlations between the metabolites resulting from common or closely linked biosynthesis pathways. Our results showed that carotenoids correlated positively with tocopherols and negatively with phytosterols; our findings also indicated a close relationship between the methylerythritol 4-phosphate and mevalonic acid biosynthesis pathways, providing evidence in favor of an earlier hypothesis regarding crosstalk across the chloroplast membrane. We, thus, demonstrate that metabolic profiling combined with multivariate analysis is a useful tool for analyzing metabolic networks.

PRACTICAL APPLICATION

A total of 71 metabolites were measured in 5 peppers of different colors. The metabolic profiling with multivariate analysis revealed that tocopherol content had a positive correlation with the carotenoid content and a negative correlation with the phytosterol content. The results of this study may help in breeding programs to produce new germplasm with enhanced nutritional quality.

Reversed-Phase High-Performance Liquid Chromatography for the Quantification and Optimization for Extracting 10 Kinds of Carotenoids in Pepper (Capsicum annuum L.) Leaves

Carotenoids are considered to be crucial elements in many fields and, furthermore, the significant factor in pepper leaves under low light and chilling temperature. However, little literature focused on the method to determinate and extract the contents of carotenoid compositions in pepper leaves. Therefore, a time-saving and highly sensitive reversed-phase high-performance liquid chromatography method for separation and quantification of 10 carotenoids was developed, and an optimized technological process for carotenoid composition extraction in pepper leaves was established for the first time. Our final method concluded that six xanthophylls eluted after about 9-26 min. In contrast, four carotenes showed higher retention times after nearly 28-40 min, which significantly shortened time and improved efficiency. Meanwhile, we suggested that 8 mL of 20% KOH-methanol solution should be added to perform saponification at 60 °C for 30 min. The ratio of solid-liquid was 1:8, and the ultrasound-assisted extraction time was 40 min.

Polyphenols content and antioxidant activity of paprika and pepper spices

Paprika spices (Capsicium annuum) and black pepper spices (Piper nigrum) are very popular seasonings for culinary and industrial utilization due to the change of sensory quality (taste, aroma, color) of foods and meals with their addition; their health promoting properties; and also, relevant antioxidant activity. Polyphenols are often responsible for the antioxidant capacity of plant products therefore in our study the content of polyphenols (TP) and antioxidant activity (TAA) were assessed in two common culinary spices - paprika spices (12, ground powder spices) and pepper spices (20, unground and ground, black, green, white and colored spices) of Czech, Austrian, and Slovak producers. These parameters were determined using spectrometric method, for total polyphenols method with Folin-Ciocaulteu reagent; the antioxidant activity (TAA) of aqueous and ethanolic extracts of spices was measured by DPPH method with IC50 evaluation. For paprika the total polyphenol content ranged from 14.67 to 28.78 mg GAE.g-1. However, there is only weak connection between the pungency of the spices and the polyphenolic amount, the hotter samples of paprika spices have slightly higher values of TP than sweet types. Also, more pungent paprika products showed a higher potency in scavenging of DPPH free radical than sweeter ones; and ethanolic extracts had slightly higher TAA values (8.73 to 16.17 mg AAE.g-1) than aqueous spice extracts (4.45 to 16.24 mg AAE.g-1). Phenolic amount for pepper spices was assessed in the range of 12.03 to 22.88 mg GAE.g-1. Generally, paprika spices contained more polyphenols than pepper spices. The values of TAA of pepper spices were in the range from 7.07 to 15.81 mg AAE.g-1 for aqueous extracts and from 8.25 to 15.93 mg AAE.g-1 for ethanolic extracts respectively. The highest TAA values were observed for white ground pepper and unground black pepper spices. Unground black pepper samples had higher TAA than ground black pepper. The extent of antioxidant activity of paprika and pepper spices was quite similar. The total phenolics contents in spices were correlated to antioxidant activity only slightly.

Ripening of pepper (Capsicum annuum) fruit is characterized by an enhancement of protein tyrosine nitration

BACKGROUND AND AIMS

Pepper (Capsicum annuum, Solanaceae) fruits are consumed worldwide and are of great economic importance. In most species ripening is characterized by important visual and metabolic changes, the latter including emission of volatile organic compounds associated with respiration, destruction of chlorophylls, synthesis of new pigments (red/yellow carotenoids plus xanthophylls and anthocyanins), formation of pectins and protein synthesis. The involvement of nitric oxide (NO) in fruit ripening has been established, but more work is needed to detail the metabolic networks involving NO and other reactive nitrogen species (RNS) in the process. It has been reported that RNS can mediate post-translational modifications of proteins, which can modulate physiological processes through mechanisms of cellular signalling. This study therefore examined the potential role of NO in nitration of tyrosine during the ripening of California sweet pepper.

METHODS

The NO content of green and red pepper fruit was determined spectrofluorometrically. Fruits at the breaking point between green and red coloration were incubated in the presence of NO for 1 h and then left to ripen for 3 d. Profiles of nitrated proteins were determined using an antibody against nitro-tyrosine (NO2-Tyr), and profiles of nitrosothiols were determined by confocal laser scanning microscopy. Nitrated proteins were identified by 2-D electrophoresis and MALDI-TOF/TOF analysis.

KEY RESULTS

Treatment with NO delayed the ripening of fruit. An enhancement of nitrosothiols and nitroproteins was observed in fruit during ripening, and this was reversed by the addition of exogenous NO gas. Six nitrated proteins were identified and were characterized as being involved in redox, protein, carbohydrate and oxidative metabolism, and in glutamate biosynthesis. Catalase was the most abundant nitrated protein found in both green and red fruit.

CONCLUSIONS

The RNS profile reported here indicates that ripening of pepper fruit is characterized by an enhancement of S-nitrosothiols and protein tyrosine nitration. The nitrated proteins identified have important functions in photosynthesis, generation of NADPH, proteolysis, amino acid biosynthesis and oxidative metabolism. The decrease of catalase in red fruit implies a lower capacity to scavenge H2O2, which would promote lipid peroxidation, as has already been reported in ripe pepper fruit.

Physiology of pepper fruit and the metabolism of antioxidants: chloroplasts, mitochondria and peroxisomes

BACKGROUND AND AIMS

Pepper (Capsicum annuum) contains high levels of antioxidants, such as vitamins A and C and flavonoids. However, information on the role of these beneficial compounds in the physiology of pepper fruit remains scarce. Recent studies have shown that antioxidants in ripe pepper fruit play a key role in responses to temperature changes, and the redox state at the time of harvest affects the nutritional value for human consumption. In this paper, the role of antioxidant metabolism of pepper fruit during ripening and in the response to low temperature is addressed, paying particular attention to ascorbate, NADPH and the superoxide dismutase enzymatic system. The participation of chloroplasts, mitochondria and peroxisomes in the ripening process is also investigated.

SCOPE AND RESULTS

Important changes occur at a subcellular level during ripening of pepper fruit. Chloroplasts turn into chromoplasts, with drastic conversion of their metabolism, and the role of the ascorbate-glutathione cycle is essential. In mitochondria from red fruits, higher ascorbate peroxidase (APX) and Mn-SOD activities are involved in avoiding the accumulation of reactive oxygen species in these organelles during ripening. Peroxisomes, whose antioxidant capacity at fruit ripening is substantially affected, display an atypical metabolic pattern during this physiological stage. In spite of these differences observed in the antioxidative metabolism of mitochondria and peroxisomes, proteomic analysis of these organelles, carried out by 2-D electrophoresis and MALDI-TOF/TOF and provided here for the first time, reveals no changes between the antioxidant metabolism from immature (green) and ripe (red) fruits.

CONCLUSIONS

Taken together, the results show that investigation of molecular and enzymatic antioxidants from cell compartments, especially chloroplasts, mitochondria and peroxisomes, is a useful tool to study the physiology of pepper fruit, particularly in the context of expanding their shelf-life after harvest and in maintaining their nutritional value.

Bioactive Compounds and Antioxidant Activity in Different Grafted Varieties of Bell Pepper

Grafting favors the presence of bioactive compounds in the bell pepper, but many species and varieties have not yet been analyzed in this sense, including commonly grafted varieties. The aim of the present study is to characterize the content in β-carotenes, vitamin C, lycopene, total phenols, and the antioxidant activity of bell pepper (Capsicum annum L) using the cultivar/rootstock combinations: Jeanette/Terrano (yellow), Sweet/Robusto (green), Fascinato/Robusto (red), Orangela/Terrano (orange), and Fascinato/Terrano (red). The plants were grown in a net-shading system and harvested on three sampling dates of the same crop cycle. The results show statistical differences (p ≤ 0.05) between cultivar/rootstock combinations and sampling dates for the content in bioactive compounds and antioxidant activity. Fascinato/Robusto presented the highest concentration of lycopene and total phenols as well as the greatest antioxidant activity of all cultivar/rootstock combinations evaluated. In addition, it was found that the best sampling time for the peppers to have the highest concentrations of bioactive compounds and antioxidant activity was September.

Influence of cultivar and ripening time on bioactive compounds and antioxidant properties in Cape gooseberry (Physalis peruviana L.)

BACKGROUND

Cape gooseberry (Physalis peruviana) is an exotic fruit highly valued for its organoleptic properties and bioactive compounds. Considering that the presence of phenolics and ascorbic acid could contribute to its functional capacity, it is important to investigate the quality parameters, bioactive contents and functional properties with respect to genotype and ripening time. In this study the genotype effect was evaluated in 15 cultivars for two different harvest times. Changes during maturation were recorded in two commercial cultivars within seven levels of maturity.

RESULTS

Multivariate statistical analysis suggested that phenolic content and ORAC value were mainly affected by harvest time and that ascorbic acid content and DPPH level were mainly affected by genotype. In addition, acidity, phenolic content, ORAC value and inhibition of LDL oxidation decreased with maturity, but soluble solids content, ascorbic acid content, β-carotene content and DPPH-scavenging activity were higher in mature fruits.

CONCLUSION

The phenolic content, ascorbic acid content and antioxidant properties of Cape gooseberry fruit were strongly affected by cultivar, harvest time and maturity state. Consequently, the harvest time must be scheduled carefully to gain the highest proportion of bioactive compounds according to the specific cultivar and the environment where it is grown.

Identification of the carotenoid modifying gene PALE YELLOW PETAL 1 as an essential factor in xanthophyll esterification and yellow flower pigmentation in tomato (Solanum lycopersicum)

Xanthophylls, the pigments responsible for yellow to red coloration, are naturally occurring carotenoid compounds in many colored tissues of plants. These pigments are esterified within the chromoplast; however, little is known about the mechanisms underlying their accumulation in flower organs. In this study, we characterized two allelic tomato (Solanum lycopersicum L.) mutants, pale yellow petal (pyp) 1-1 and pyp1-2, that have reduced yellow color intensity in the petals and anthers due to loss-of-function mutations. Carotenoid analyses showed that the yellow flower organs of wild-type tomato contained high levels of xanthophylls that largely consisted of neoxanthin and violaxanthin esterified with myristic and/or palmitic acids. Functional disruption of PYP1 resulted in loss of xanthophyll esters, which was associated with a reduction in the total carotenoid content and disruption of normal chromoplast development. These findings suggest that xanthophyll esterification promotes the sequestration of carotenoids in the chromoplast and that accumulation of these esters is important for normal chromoplast development. Next-generation sequencing coupled with map-based positional cloning identified the mutant alleles responsible for the pyp1 phenotype. PYP1 most likely encodes a carotenoid modifying protein that plays a vital role in the production of xanthophyll esters in tomato anthers and petals. Our results provide insight into the molecular mechanism underlying the production of xanthophyll esters in higher plants, thereby shedding light on a longstanding mystery.

Phytochemicals in date co-products and their antioxidant activity

The date agro-industry needs to find appropriate techniques to give value to their co-products. This study analyzes twelve intermediate food products (IFPs) from date co-products, Medjool and Confitera cv. at several ripening stages, blanched and unblanched, for their content in bioactive compounds (phenols, tannins, flavonoids, carotenoids and anthocyanins) and the antioxidant activity (AA). IFPs from the more unripe stages had the highest AA and phytochemicals content, mainly phenols, up to 1.4 g GAE/100 g, with high proportions of tannins. Flavonoids were found in high amounts, up to 874 mg RE/100 g. Among the AA are significant the antiradical efficiency (4.62 mM TE/100 g) and chelating activity (252 μM EDTA/100 g). Blanching was beneficial for Confitera IFPs. A positive correlation was found between phenols, tannins and flavonoids and the AA; and their content could be used as indicator of the AA. Date IFPs have potential use as an antioxidant functional ingredient.

Red pepper (Capsicum annuum) carotenoids as a source of natural food colors: analysis and stability-a review

Carotenoids are increasingly drawing the attention of researchers as a major natural food color due to their inherent nutritional characteristics and the implicated possible role in prevention and protection against degenerative diseases. In this report, we review the role of red pepper as a source for natural carotenoids. The composition of the carotenoids in red pepper and the application of different methodologies for their analysis were discussed in this report. The stability of red pepper carotenoids during post-harvest processing and storage is also reviewed. This review highlights the potential of red pepper carotenoids as a source of natural food colors and also discusses the need for a standardized approach for the analysis and reporting of composition of carotenoids in plant products and designing model systems for stability studies.