SICHUAN PEPPER

Spicy
Written By Fulvio Ciccolo

Sichuan Pepper

SICHUAN PEPPER

NATURAL INGREDIENT FOR PERFUMERY OVERVIEW

🔎 Botanical Name: Zanthoxylum Schinifolium

Before we venture into the specific description, use, extraction method, and olfactory profile regarding Sichuan Pepper, it is important to highlight a fundamental discrepancy that might otherwise lead some readers astray.

When talking about Sichuan Pepper (also known as Szechuan Pepper, Szechwan Pepper, or Chinese Prickly Ash) seeing the spice defined as “pepper” might lead to the conclusion that the Chinese berries are somehow related, both for their botanical ancestry and their olfactory and aromatic properties, to the family of the Piperaceae; however, this couldn’t be further from the truth. Contrarily from what its denomination might suggest, Sichuan Pepper belongs to the Zanthoxylum Genus in the macrofamily of Rutaceae (also known as the rue family or citrus family) while Black Pepper belongs to the Piper Genus in the family of Piperaceae.

The Zanthoxylum Genus (compound name derived from the Greek words 'Xanthos' meaning yellow, and 'Xylon', wood) comprises more than 200 species of deciduous trees, shrubs, and climbers. It is also the only Genus in the citrus family to have a natural tropical distribution. Plants belonging to this Genus are usually characterized by their dense foliage, prickled trunk and branches, and the production of small, pungent, round berries. These berries can range in color from green, which is distinctive of Zanthoxylum Schinifolium, to red for Zanthoxylum simulans. Differently from the fruits produced by Piper Nigrum **(the botanical name for the widely renowned Black Pepper) which has a peculiar warm, spicy, and pungent perfume, while also standing out for their distinctive hotness and spicy flavor, the fruits belonging to the Zanthoxylum Genus lack the characteristic acute hotness, presenting instead more citrus-like facets.

Another distinguishing feature that sets the berries produced by plants within the Zanthoxylum Genus apart from the ones yielded by Black pepper is the distinct tingling and numbing sensation they impart to the mouth.

Sichuan Pepper Overview

Zanthoxylum schinifolium, commonly referred to as Sichuan Pepper, was originally cultivated in the Chinese region of Sichuan from which its name is derived. Historically known for its versatility and taste, Zanthoxylum schinifolium has been adopted in many fields of interest, such as culinary, perfumery, cosmetics, and traditional oriental medicine.

Although it is impossible to pinpoint the first time that the Sichuan peppercorns were introduced to Chinese pantries, recorded history reports that was not until 420-589 AD that the Sichuan peppers started spreading throughout China. In the culinary world, Sichuan peppercorns can be used in more ways than one: from grinding the peppercorns into powder to be added during the cooking process or as garnishment for the plate, while it is also possible to be used in the form of oil to be applied during the earlier stages of preparation.

When it comes to the choices between green or red peppercorns, it has been reported that the green ones, the ones derived from Zanthoxylum Schinifolium, have a more potent, zesty, citrusy, and slightly floral flavor, while having a mild numbing effect. On the other hand, the red Sichuan peppercorns have a more pronounced, pungent aroma with a bitter, woody flavor, retaining a stronger numbing effect.

The already mentioned numbing and tingling sensation caused by the consumption of Sichuan Pepper has been another intriguing point of interest for years. In the history of traditional oriental medicine, due to its anesthetic properties, Sichuan Pepper has been utilized to treat toothache and digestive impairments. It has also been employed as a mild analgesic, thus becoming a staple in this branch of natural medicine. These portentous effects have been linked to a specific molecule of the Alkamide group, also known as Alkylamides, and it has been identified in every Zanthoxylum variety. Hydroxy-alpha-sanshool is the unsaturated fatty acid amide responsible for the above-mentioned responses thanks to its role as an agonist (a substance that initiates a physiological response) at the pain integration channels. Recent studies have also shown a direct interaction between Hydroxy-alpha-sanshool and the tandem pore domain potassium channels that might eventually deepen our knowledge regarding Sichuan Pepper as a natural pain inhibitor. Furthermore, Sichuan Pepper has also been recognized as a potent antioxidant.

These peculiar characteristics and reactions of the Sichuan Pepper have also found resonance in the cosmetic field. In fact, research conducted on the Zanthoxylum bungeanum variant showed that its pericarps appear to secrete an oil-like substance used by dermatologists and in cosmetic formulations to alleviate skin discomfort, possible itching, and inflammation of sensitive skin. Moreover, it has been shown that the lipophilic extract of the pericarp might possess lifting and anti-aging properties.

Sichuan Pepper in Perfumery

Method of extraction: Supercritical Fluid Extraction (SFE)

Sichuan Pepper has been employed for a long time in perfumery to impart distinctive green, zesty, and occasionally sweet notes to a wide range of fragrances. However, to render the handpicked berries suitable for perfumery, two unavoidable steps need to be taken to preserve the pure and clean profile of the product while maintaining a very close resemblance to the raw material. First, the berries need to be sun-dried or left to dry in dedicated cellars and, after the drying process, the berries have to undergo an extraction process named Supercritical Fluid Extraction (SFE).

SFE consists of a process intended to extract in the most efficient and environmentally friendly way specific compounds from natural products. Thus, to enable the process to proceed as intended, a Supercritical Fluid (or SCF) needs to be selected. The term SFC is directed towards materials that, once they have surpassed both their critical temperature and pressure, adopt both properties from gasses and liquids. The SFC of choice that has often been adopted due to its ability to extract nonpolar solutes while being extremely easy to separate from the resulting product is Carbon Dioxide (CO2).

After the Sichuan Pepper berries have been properly dried they can be either grounded or directly moved into an extraction basket of which both the bottom and top are equipped with filter frits, permitting the necessary circulation of CO2. Subsequently, the basket is lowered inside the extractor chamber. Once the extractor chamber has been closed, a pump starts forcing the CO2 through, pressurizing it and heating it until it reaches the opportune temperature (31.1 °C) and pressure (73.8 bar) required to transition into its Supercritical state (scCO2). The scCO2 will then operate as a solvent in this state, dissolving the desired compound.

From the extractor, the scCO2 moves through a pressure valve, flowing inside the separator. As its name might suggest, inside the separator, due to a lower pressure, the CO2 gets separated from the desired compound. From the separator, the resulting substance gets extracted and captured in a collection vessel, free of any solvent and ready to be processed to the manufacturer’s desire. From here, the CO2 gets separated from the substance and, in its gaseous form, passes through a valve which eases its reintegration in its original tank, ready to be re-used. The possibility to re-use the Carbon Dioxide in a constant loop of tightly connected tanks is also referred to as a Closed Loop System.

Sichuan Pepper SFE Olfactory Profile (Zanthoxylum Schinifolium)

Sichuan Pepper SFE is an aromatic absolute, thus denser than oil, presenting a yellow to orange color, which can be used in fragrances to intensify, invigorate, highlight, and at times consistently modify the perfume.

It is possible to state that, when it comes to its effects on specific fragrances, thanks to its characteristic properties, Sichuan Pepper SFE can massively interact in two fundamental ways. First of all, due to the high presence of terpenes in the pepper extract, the substance can be used to heavily influence the top notes, thus shaping the preliminary perception of the fragrance. Secondarily, thanks to its viscous nature, the extract can also consistently interact with the heart notes, becoming a precious contributor to the stability and depth of the overall olfactory experience.

The Sichuan Pepper SFE olfactory profile has often been described as possessing peculiarly spicy, lemony, and animalistic notes while presenting characteristic sweet facets reminiscent of grapefruit which are often paired with vetiver. Other peculiar notes that can be recognized upon further inspection are the citrusy, fragrant, and bitter notes reminiscent of Petitgrain while presenting a feint metallic undertone.

In conclusion, Sichuan Pepper SFE can be then used to sustain, enrich, and or modify the fresh and zesty notes of the various fragrances in which it can be used, becoming a delicate, scented support in the head notes, or take on a foundational function at the center of the heart notes.

 

Sources:

Fulvio Ciccolo
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