Capsaicinoids

Capsaicinoids are the group of substances that give hot pepper (Capsicum) its pungency. The main members are capsaicin, dihydrocapsaicin, and nordihydrocapsaicin. Food manufacturers buy pepper extract for pungency, color, and aroma. Supplement, cosmetic, and feed manufacturers also use it, each under its own regulations.

How much is in the pepper?

Capsaicinoids accumulate in the internal tissue (placenta) where seeds attach in the pepper fruit [10]. The seeds themselves and the fleshy outer part contain less. The amount is not constant even within the same variety. A study measured Jalapeño, habanero, and Bhut Jolokia samples. Capsaicinoid content varied widely across suppliers and even from fruit to fruit within the same supplier [2]. Therefore, the pungency of an extract is determined by the measured capsaicinoid ratio, not by the plant name.

Capsaicin, dihydrocapsaicin, nordihydrocapsaicin: what is the difference?

Values come from PubChem. XLogP shows whether a molecule prefers oil or water. Higher values mean a stronger preference for oil. All three molecules are insoluble in water and soluble in oil and ethanol.

All three share the same backbone. They differ slightly in their side chains. All three occur together in natural pepper extract. Capsaicin and dihydrocapsaicin are the two major components [8], [12]. In oleoresin samples, capsaicin is more abundant than dihydrocapsaicin [3], [5]. If a certificate lists only "capsaicin", ask whether that means total capsaicinoids or the single component.

What is it used for?

Food: pungency, color, aroma. The main market for capsaicinoid extracts is food. It provides pungency in sauces, spice blends, snacks, and meat products. Oleoresin (solvent-extracted oily extract) also adds color and aroma. A review of industrial uses of pepper derivatives notes that pepper extracts have potential to extend shelf life as additives that slow oxidation and microbial growth, though stability and safety studies remain insufficient [11].

There are five fields outside food. Each is a separate product class and subject to separate regulations.

• Pharmaceuticals. High-concentration (8%) capsaicin patches are used as drugs for chronic neuropathic pain. A Cochrane review examined 8 studies and 2,488 patients. It notes that roughly 10% more patients reported meaningful pain reduction with the patch than with the control group (low-concentration patch). It rates evidence quality between moderate and very low. It finds the effect similar to other chronic pain treatments [14]. These products are subject to pharmaceutical regulations. They are not the same as food-grade extract.
• Supplements. A review compiling 20 studies and 563 individuals reports that capsaicinoid intake increases daily energy expenditure by about 50 kcal, increases fat oxidation, and decreases appetite. Regular intake also reduced abdominal fat and calorie consumption. The authors note that capsaicinoids do not cause weight loss alone, but can be part of a weight management program [16]. The supplement market relies on these findings.
• Cosmetics. According to the Cosmetic Ingredient Review (CIR) expert panel, Capsicum derivatives are used in cosmetics as skin-conditioning agents, external analgesics, flavoring agents, and fragrance ingredients. As of the report date, they appear in 19 products up to 5%. The panel concludes these ingredients are safe when formulated to be non-irritating [17].
• Feed. The European Food Safety Authority (EFSA) evaluated a feed additive containing carvacrol, cinnamaldehyde, and capsicum oleoresin for chickens for fattening. The additive was found safe for animals, consumers, and the environment at 100 mg/kg. The panel states it has potential to improve performance and recommends treating it as a skin, eye, and respiratory irritant [15].
• Defense sprays. Oleoresin capsicum is the active ingredient in defense sprays. A study measuring commercial sprays reports that capsaicinoid content varies across manufacturers and between lots from the same manufacturer. Although products are classified by Scoville units, they are not standardized by capsaicinoid content [12].
• Animal repellents. In a field trial in Zimbabwe, capsicum oleoresin spray repelled elephants from crop fields significantly faster than traditional methods [13].

The same extract cannot be used in all these fields. The field determines the specification and documentation.

3% or 10%: which extract?

Capsaicinoids are sold within a pepper extract rather than on their own. Two forms are common.

In extraction, pressure and temperature alter both yield and capsaicinoid ratio [3]. Higher pressure also increases the yield of coloring carotenoids [4]. As the ratio increases, less extract is needed for the same capsaicinoid amount. Accompanying oil and color decrease. Selection depends on four questions.

• How much capsaicinoid is needed? 1 g of 3% extract contains 30 mg capsaicinoids. Adding 1 g of 3% extract to 1 kg sauce yields 30 mg/kg capsaicinoids in the sauce. For the same amount, 0.3 g of 10% extract is enough. These numbers are examples, not dosage recommendations.
• Are color and aroma desired? In products like sauces, oleoresin color and aroma are desirable. Capsule space is limited, so higher concentrations reduce fill volume.
• Weighing and mixing. 10% extract is concentrated. It requires more protection and more careful homogenization.
• Price. Compare the price per kilogram of capsaicinoids, not per kilogram of extract. A 3% extract at 100 units/kg equals 3,333 units/kg capsaicinoids. A 10% extract at 250 units/kg equals 2,500 units/kg capsaicinoids. These numbers are examples.

How to read an analysis report?

Method. Capsaicinoid measurement evolved from taste tests to laboratory methods [1]. Today the standard method is HPLC (liquid chromatography). HPLC measures individual components separately. Older methods based on light absorbance yield only the total. If no method is stated on the certificate, ask.

Total capsaicinoids and capsaicin are not the same. Some documents state the total. Others state the single component. In an extract with 5% total capsaicinoids, capsaicin alone may be 3.5%. These numbers are examples. Compare identical metrics across documents.

Scoville heat units (SHU) are a calculation, not a direct measurement. It was originally a taste test [1]. Today it is calculated from the HPLC-determined capsaicinoid ratio using a conversion factor [9]. The factor varies by source. In one study, pure capsaicin corresponds to 16 million SHU [8]. Another study measuring oleoresin samples uses approximately 15 million for total capsaicinoids [12]. Correlation between total capsaicinoids and taste tests has been shown in peppers and oleoresins [7]. The same extract yields different SHU values with 15 million versus 16 million. Ask for the factor before comparing two SHU values.

Specification and measured values are different things. Specification is the lower or upper limit committed by the manufacturer. The measured value is the result for that specific lot. A technical data sheet (TDS) is a general document. A certificate of analysis (CoA) belongs to a single lot. The binding documents for purchasing are the specification and the lot CoA.

What indicates quality?

Component profile. Capsaicin, dihydrocapsaicin, and nordihydrocapsaicin occur together in natural extracts. If the certificate lists only "capsaicin", check that total and individual values are not confused.

Accompanying substances. Pigment and fixed oil ratios in oleoresin vary by process. Both reduce the capsaicinoid concentration.

Solvent residues. Residues depend on the extraction solvent. Request residual solvent limits for solvent-extracted products. Ask the same question if co-solvents are used in CO₂ extraction.

Certificate requirements. Method name, individual capsaicinoids and total, loss on drying, heavy metals (As, Cd, Pb, Hg), and microbiology. For raw materials: pesticides, aflatoxins, ochratoxin A, and benzo(a)pyrene.

How does it behave in formulation?

Solubility. Capsaicinoids are insoluble in water but soluble in oil and ethanol. In one study, an oil-based system showed better heat stability than a water-based system [6]. Therefore, an oil phase or emulsion is considered in water-based formulations.

Light, heat, and storage. In the same study, UV light reduced capsaicinoid content in both water and oil systems. Storage at 4 °C delayed degradation [6]. Capsaicin in habanero oleoresin remained stable for 35 days of storage [5]. Store extracts in a cool, dry place away from light and heat. Shelf life is stated in manufacturer documentation.

Irritation. Capsaicinoids irritate the skin, eyes, and respiratory tract. Weighing concentrated extracts requires gloves, goggles, and ventilation. Closed systems are preferred for high-concentration extracts. Details are provided in the product safety data sheet (SDS).

Labeling. Cosmetic ingredient names (INCI) depend on the pepper species. The proper identifier on the label depends on the product class and applicable regulations.