Red Bell Peppers(  Capsicum annuum)

Fruit of the Solanaceae family harvested at different ripeness stages (green = unripe; yellow/orange/red = ripe). Includes blocky/bell, horn/corno, quadrangular, and thin-flesh types (for drying). Used fresh, roasted/smoked, preserved (grilled in oil, brined/pickled), dried (e.g., paprika), and as color extracts.

Common name: Red bell pepper

Source plant: Capsicum annuum L. (family Solanaceae)

Kingdom: Plantae
Clade: Angiosperms
Clade: Eudicots
Order: Solanales
Family: Solanaceae
Genus: Capsicum
Species: Capsicum annuum L.

Note: Red bell peppers are simply the fully ripe fruits of sweet (non-pungent) Capsicum annuum cultivars. They are green at the immature stage and turn red as they ripen, becoming sweeter, more aromatic and richer in carotenoids and vitamin C.

Cultivation and growing conditions of red bell peppers

• Climate:

  • Prefer warm, temperate to warm–subtropical climates.

  • Sensitive to low temperatures and frost.

  • Need a relatively long, warm growing season to complete ripening from green to red.

• Exposure:

  • Require full sun (6–8 hours per day).

  • Shade reduces yield, sweetness and colour intensity.

• Soil:

  • Thrive in fertile, deep, well-drained, medium-textured soils.

  • Ideal pH: slightly acidic to neutral (about 6–7).

  • Poorly adapted to heavy, compact or waterlogged soils, which favour root rot and fungal diseases.

• Watering:

  • Need regular, moderate irrigation, keeping the soil consistently slightly moist.

  • Strong alternation between drought and heavy watering can cause:

    • blossom-end rot

    • fruit cracking

    • flower and fruit drop

  • Slightly reducing irrigation in the last weeks can favour more intense red colouring.

• Temperature:

  • Optimal seed germination: about 20–28 °C.

  • Optimal vegetative growth and fruit development: 20–30 °C.

  • Growth slows significantly below about 12–14 °C.

• Fertilization:

  • Benefit from a good basal supply of organic matter (compost, well-rotted manure).

  • Phosphorus and potassium are important for flowering, fruit set and fruit quality.

  • Nitrogen should be applied in moderation: excess nitrogen → vigorous foliage, fewer fruits and more susceptibility to disorders.

• Crop management:

  • Early weed control during initial growth stages.

  • Organic mulching helps maintain stable soil moisture and limit weed competition.

  • Staking can be useful in tall or heavily loaded plants to prevent lodging or branch breakage.

  • Light pinching can encourage branching and more uniform fruiting.

• Harvest:

  • Fruits can be picked green, but to obtain red bell peppers they must be left on the plant until fully ripe and uniformly red.

  • Red fruits are sweeter, more aromatic and have higher antioxidant content than green ones.

  • Regular picking of ripe fruits stimulates continued flowering and fruit set.

• Propagation:

  • By seed, usually sown in protected seedbeds or trays.

  • Seedlings are transplanted when outdoor temperatures are reliably mild and the risk of frost has passed.

Caloric value (per 100 g, edible portion)
~20–31 kcal • Water ~90–93 g • Carbohydrates ~4–6 g (mainly glucose/fructose) • Fiber ~1.5–2.5 g • Protein ~0.9–1.3 g • Fat ~0.2–0.4 g • Sodium ~2–5 mg.
Very high vitamin C (green ~80–120 mg, red ~120–150+ mg/100 g); provitamin A carotenoids higher in red/orange fruit.

Key constituents

• Carotenoids: in reds capsanthin, capsorubin, β-carotene; in yellows violaxanthin, lutein; in greens chlorophylls.

• Volatiles: methoxypyrazines (e.g., IBMP → “green” note), light terpenes, C6 aldehydes.

• Polyphenols: quercetin, luteolin (concentrated in skins).

• Capsaicinoids: negligible in sweet peppers (no pungency); some cultivars carry capsinoids (non-pungent).

• Minerals: K, Mn, Cu; nitrates generally low (↑ with intensive fertilization).

Lipid profile (per 100 g; always specified)
Total fat 0.2–0.4 g with a percentage distribution largely PUFA and MUFA but nutritionally insignificant at typical intakes:

• SFA ~10–20% • MUFA ~25–35% • PUFA ~45–60% (n-6 predominant; n-3 trace). Cholesterol: absent.

Production and processing
Field/greenhouse cultivation → harvest at target color → grading/washing → fresh use or processing:

• Roasting/charring → peeling; pack under MAP or in oil/brine.

• Acidification/pickling (pH < 4.6 for safety).

• Drying (air/sun/oven) → paprika; possible smoking (e.g., pimentón de la Vera).

• Extraction with solvents/oil → paprika extract (E160c); standardized in ASTA color units.

Sensory and technological properties

• Aroma: green-herbaceous (methoxypyrazines) to sweet-fruity in ripe fruit, with caramelized/smoky notes from roasting.

• Color: chlorophyll (green) → carotenoids (yellow/red) during ripening.

• Texture: cell walls rich in pectin; brief blanching and calcium additions (e.g., CaCl₂) help retain crispness in pickles.

• Color stability: carotenoids are lipophilic and sensitive to light/O₂/heat; encapsulation/oil carriers and antioxidants (tocopherols/rosemary extract) improve stability.

Food applications
Crudités and salads, soffritto/bases, stuffed peppers, grilled/roasted antipasti and sandwiches, sauces (e.g., ajvar, romesco), pickles, paprika as spice/color, paprika extract (E160c) for snacks, cheeses, sauces.
Indicative industrial dosages: paprika 0.05–0.5% (per ASTA target); E160c according to color yield and local limits.

Nutrition and health
Low energy, high vitamin C and carotenoids (in ripe fruit); useful fiber. Non-pungent (no capsaicin). Sensitive individuals may experience allergy (see below) or reflux with large raw portions. (No health claims without authorization.)

Quality and specifications (typical topics)
Ripeness/color, firmness (shear), °Brix, organic acids (pH), pesticide residues within MRLs, microbiology on ready-to-eat items (pathogens absent). For paprika: moisture, ASTA color, particle size, aflatoxins/ochratoxin (where relevant), metals; for extracts: total carotenoids, oxidative status, residual solvents.

Storage and shelf life
Fresh peppers: 7–10 °C, RH 90–95% (chilling injury below ~7 °C → pitting/softening); avoid high ethylene (accelerates senescence). Roasted: keep refrigerated; pickled/in oil: meet pH/aw criteria. Paprika: store dark and dry (low aw) in barrier packs (low OTR) to limit fading; apply FIFO.

Allergens and safety
Pepper is not among the EU major 14 allergens, but specific allergies are reported (LTP Cap a 1) and cross-reactivity (e.g., birch/latex–fruit syndromes). Microbiological risks arise from post-harvest contamination (hygienic handling/wash). Ensure appropriate pH in acidified preserves.

INCI functions in cosmetics
Entries: Capsicum Annuum Fruit Extract, Capsicum Annuum (Paprika) Extract. Roles: colorant, antioxidant/skin conditioning (carotenoids). Prevent photodegradation (amber/barrier packs).

Sustainability and supply chain
Field or greenhouse crops; manage irrigation and fertilization (leaching risk). Improvements: IPM (integrated pest management), by-product recovery for carotenoids/pectin, reduced greenhouse plastics, effluent management to BOD/COD targets, recyclable packaging.

Troubleshooting

• Over-green/“bell pepper” note (methoxypyrazines) → use ripe fruit; roast/peel; balance with acid and sweetness.

• Paprika/extract fading → light/O₂/heat → upgrade barrier, lower T, add permitted antioxidants.

• Soft pickles → pectin breakdown → brief blanch, add CaCl₂, control pH and process temperature.

• Cooked/browned off-notes → overcooking → use shorter cooks and moderate finishing heat.

Conclusion
Sweet pepper combines low calories, very high vitamin C, and carotenoid-rich color with wide versatility from fresh use to paprika and extracts. Performance depends on ripeness, management of light/O₂/heat, and appropriate processing (roasting, drying, acidification).

Fresh pepper contains phenols, flavonoids, capsaicinoids, ascorbic acid, all components that exert an antioxidant activity. In the treated pepper there are fewer phytochemical components and the antioxidant activity is lower (1). Cooking the pepper subtracts at least 60% of vitamin C.

Capsaicin is the alkaloid that gives the pepper its spicy taste, it is a component with antioxidant properties.

An extract from the leaves of pepper significantly inhibited inflammatory cytokine production, inhibited cell proliferation without producing cytotoxicity, and suppressed the expression of inflammatory proteins (2).

Among the polyphenols present, caffeic acid, quercetin and kaempferol have the highest amounts and have shown antimicrobial activity (3).

From green bell pepper, an extract of pectic polysaccharides showed antineoplastic activity in breast cancer, in vitro and in vivo (4).

Bell peppers studies

References_____________________________________

(1)   Alvarez-Parrilla E, de la Rosa LA, Amarowicz R, Shahidi F. Antioxidant activity of fresh and processed Jalapeño and Serrano peppers. J Agric Food Chem. 2011 Jan 12;59(1):163-73. doi: 10.1021/jf103434u.

Abstract. In this research, total phenols, flavonoids, capsaicinoids, ascorbic acid, and antioxidant activity (ORAC, hydroxyl radical, DPPH, and TEAC assays) of fresh and processed (pickled and chipotle canned) Jalapeño and Serrano peppers were determined. All fresh and processed peppers contained capsaicin, dihydrocapsaicin, and nordihydrocapsaicin, even though the latter could be quantified only in fresh peppers. Processed peppers contained lower amounts of phytochemicals and had lower antioxidant activity, compared to fresh peppers. Good correlations between total phenols and ascorbic acid with antioxidant activity were observed. Elimination of chlorophylls by silicic acid chromatography reduced the DPPH scavenging activity of the extracts, compared to crude extracts, confirming the antioxidant activity of chlorophylls present in Jalapeño and Serrano peppers.

(2)   Hazekawa M, Hideshima Y, Ono K, Nishinakagawa T, Kawakubo-Yasukochi T, Takatani-Nakase T, Nakashima M. Anti-inflammatory effects of water extract from bell pepper (Capsicum annuum L. var. grossum) leaves in vitro. Exp Ther Med. 2017 Nov;14(5):4349-4355. doi: 10.3892/etm.2017.5106.

Abstract. Fruits and vegetables have been recognized as natural sources of various bioactive compounds. Peppers, one such natural source, are consumed worldwide as spice crops. They additionally have an important role in traditional medicine, as a result of their antioxidant bioactivity via radical scavenging. However, there are no reports regarding the bioactivity of the bell pepper (Capsicum annuum L. var. grossum), a commonly used edible vegetable. The present study aimed to evaluate the anti-inflammatory effect of water extract from bell pepper leaves on mouse spleen cells, and explore the potential mechanism underlying this effect. The extract was prepared through homogenization of bell pepper leaves in deionized water. The sterilized supernatant was added to a mouse spleen cell culture stimulated by concanavalin A. Following 72 h of culture, the levels of inflammatory cytokines in the culture supernatant were measured using a sandwich enzyme-linked immunosorbent assay system, and levels of inflammatory proteins were assessed using western blotting. The bell pepper leaf extract significantly inhibited inflammatory cytokine production, inhibited cell proliferation without producing cytotoxicity, and suppressed the expression of inflammatory proteins. These results suggest that components of the bell pepper leaf extract possess anti-inflammatory activity. The study of the anti-inflammatory mechanism of bell pepper leaf extract has provided useful information on its potential for therapeutic application.

(3) Mokhtar M, Ginestra G, Youcefi F, Filocamo A, Bisignano C, Riazi A. Antimicrobial Activity of Selected Polyphenols and Capsaicinoids Identified in Pepper (Capsicum annuum L.) and Their Possible Mode of Interaction Curr Microbiol. 2017 Nov;74(11):1253-1260. doi: 10.1007/s00284-017-1310-2.

Abstract. Antimicrobial activity of pepper polyphenols and capsaicinoids (Coumarin, caffeic acid, narangin, kaempferol, rutin, quercetin, capsaicin, and dihydrocapsaicin) against 13 pathogen bacteria and three beneficial strains was studied using the disk diffusion and microdilution methods. In general, phenolic compounds had the most important activity with the highest inhibition zones obtained with caffeic acid (3.5-20.5 mm), quercetin (4.75-3.5 mm), and kaempferol (7-14 mm). In the determination of the minimal inhibitory concentrations, the effects of both quercetin and kaempferol were more important than caffeic acid. The clinical strains Staphylococcus aureus (319, 14, 8, 32, and 550) were more sensitive to quercetin (0.00195-0.0078 mg L-1) whereas kaempferol was more active against the strains S. aureus (ATCC 6538, 26), S. typhimurium ATCC 13311, and Pseudomonas aeruginosa ATCC 27853 (0.0156-0.125 mg L-1). The interaction between these three polyphenols was studied against S. aureus ATCC 6538 and P. aeruginosa ATCC 27853. Different modes of interaction were observed (synergism, additive, and indifferent), but no antagonism was obtained. The best combination was quercetin and caffeic acid for S. aureus with fractional inhibitory concentration index (FICI) of 0.37, and kaempferol with quercetin for P. aeruginosa (FICI = 0.31).

(4)  Adami ER, Corso CR, Turin-Oliveira NM, Galindo CM, Milani L, Stipp MC, do Nascimento GE, Chequin A, da Silva LM, de Andrade SF, Dittrich RL, Queiroz-Telles JE, Klassen G, Ramos EAS, Cordeiro LMC, Acco A. Antineoplastic effect of pectic polysaccharides from green sweet pepper (Capsicum annuum) on mammary tumor cells in vivo and in vitro. Carbohydr Polym. 2018 Dec 1;201:280-292. doi: 10.1016/j.carbpol.2018.08.071.

Jang HH, Lee J, Lee SH, Lee YM. Effects of Capsicum annuum supplementation on the components of metabolic syndrome: a systematic review and meta-analysis. Sci Rep. 2020 Dec 1;10(1):20912. doi: 10.1038/s41598-020-77983-2.

Abstract. Metabolic syndrome (MetS) has increasingly gained importance as the main risk factor for cardiovascular diseases and type II diabetes mellitus. Various natural compounds derived from plants are associated with beneficial effects on the incidence and progression of MetS. This study aimed to evaluate the effects of Capsicum annuum on factors related to MetS by assessing randomized controlled trials (written in English). We searched the online databases of PubMed, Embase, Google scholar, and Cochrane Library up to April 2020. 'Patient/Population, Intervention, Comparison and Outcomes' format was used to determine whether intervention with C. annuum supplementation compared with placebo supplementation had any effect on the components of MetS among participants. We considered standardized mean differences (SMD) with 95% confidence intervals (CI) as effect size measures using random-effects model. Analysis of the included 11 studies (n = 609) showed that C. annuum supplementation had significant effect on low density lipoprotein-cholesterol [SMD = - 0.39; 95% CI - 0.72, - 0.07; P = 0.02; prediction interval, - 1.28 to 0.50] and marginally significant effect on body weight [SMD = - 0.19; 95% CI - 0.40, 0.03; P = 0.09]. However, larger and well-designed clinical trials are needed to investigate the effects of C. annuum on MetS.

Heidmann I, Boutilier K. Pepper, sweet (Capsicum annuum). Methods Mol Biol. 2015;1223:321-34. doi: 10.1007/978-1-4939-1695-5_26.

Abstract. Capsicum (pepper) species are economically important crops that are recalcitrant to genetic transformation by Agrobacterium (Agrobacterium tumefaciens). A number of protocols for pepper transformation have been described but are not routinely applicable. The main bottleneck in pepper transformation is the low frequency of cells that are both susceptible for Agrobacterium infection and have the ability to regenerate. Here, we describe a protocol for the efficient regeneration of transgenic sweet pepper (C. annuum) through inducible activation of the BABY BOOM (BBM) AP2/ERF transcription factor. Using this approach, we can routinely achieve a transformation efficiency of at least 0.6 %. The main improvements in this protocol are the reproducibility in transforming different genotypes and the ability to produce fertile shoots. An added advantage of this protocol is that BBM activity can be induced subsequently in stable transgenic lines, providing a novel regeneration system for clonal propagation through somatic embryogenesis.