Abstract
Black pepper is a complex spice; its aroma reflects its geographical origin, chemical composition, and distinct characteristics. While gas chromatography-mass spectrometry (GC-MS) and sensory analysis have been widely applied to beverages like wine, tea, and coffee, few studies have examined this dual approach in spices to objectively quantify geographical indication (GI) traits. This study aims to fill that gap by establishing specific sensory-chemical fingerprints for Vietnamese black pepper. Using descriptive sensory analysis and GC-MS, we identified significant regional variations in both aroma profiles and volatile compound composition. Among 11 sensory descriptors, 8 showed statistically significant differences between provinces. GC-MS revealed 117 volatile compounds, of which 106 were shared across all regions, forming a core chemical fingerprint. The strongest citrus and floral aromas were observed in Gia Lai samples, while Quang Tri peppers were defined by fatty and pungent notes. A strong RV coefficient (0.88) between sensory data and GC-MS results highlights the strong correlation between aroma perception and chemical composition. The implementation of these standardized regional aroma specifications has the potential to strengthen geographical indication (GI) applications and traceability systems not only for Vietnamese black pepper, but also for a wide range of spice and agriculture products globally.
1 Introduction
Black pepper (Piper nigrum L.) is one of the most economically significant spices globally, and Vietnam is currently the world’s largest producer and exporter, supplying a major share of the international market. However, in order to sustain and expand market share in the increasingly competitive international market, the pepper industry must focus on improving product quality and aligning with stringent global standards. This context underscores the urgent need for robust scientific approaches to authenticate geographical origin, enhance quality differentiation, and strengthen the value proposition of Vietnamese black pepper.
In recent years, the integration of sensory science with instrumental techniques such as gas chromatography–mass spectrometry (GC-MS) has revolutionized quality control and origin authentication in high-value agricultural products. This multi-layered method has been effectively applied to a variety of foods and drinks, such as strong wine, honey, peas and cheese, to detect quality differences, determine geographical origin, and identify fraud through volatile compounds (volatilome) (Zhang et al., 2021; ; ). Coffee studies show that combining sensory data and GC-MS can identify typical volatile compounds associated with each planting area, thereby supporting product valuation, building flavor map and traceability by geographical area (). Similarly, the studies of tea using GC-IMS and sensory analysis have classified the origin and quality level effectively, contributing to increasing brand positioning in the international market (). These approaches are also successfully applied in analysis of fermented products such as chocolate and cheese, where the flavor characteristics are the result of the combination of microbiological interactions, raw materials, processes and production conditions (; Zheng et al., 2024).
However, while applications that integrate sensory and chemistry are increasingly popular in drinks and foods, for the group of spices and herbs, especially those of high economic and cultural value such as black pepper (Piper nigrumL.), studies in this direction are still very limited (; ). The majority of spice studies still focus on describing chemical composition or biological activity, but has not paid strong attention to the connection of chemical properties with senses and geographical origin (). Although the dossier of the evaporation compounds of black pepper has been defined quite clearly, with monoterpenes groups such asα-pinene, β-pinene, δ-3-carene, limonene and sesquiterpenes, the connection of these compounds with specific sensory characteristics and geographical origin remains unexplored (; ). Studies conducted in Madagascar, Brazil, and Indonesia have revealed differences in the main volatile compounds present in black pepper, such as α-Pinene, Sabinene, β-Pinene, δ-3-Carene, Limonene and β-Caryophyllene, highlighting the influence of regional factors (terroir) on its chemical profile (; ). However, efforts to establish a direct relationship between volatile compounds and sensory awareness to serve the authenticity of geographical origin (GI) are still very rare, especially in Vietnam - the world’s largest pepper export country.
Meanwhile, a number of recent studies have demonstrated the strong potential of this integrated approach for other spices. A study published in Frontiers in Nutrition (2023) highlights the use of GC-IMS combined with chemometric analysis to authenticate and classify Chinese GI agricultural and food products, including rice, meat, tea, wine, Baijiu, honey, and oils. Data fusion of multiple techniques (LC-MS, GC-IMS, E-nose) enhances accuracy and addresses limitations of individual methods (Zhu et al., 2023). Additionally, a 2024 study in Frontiers in Nutrition analyzed Chinese specialty soup Hulatang using both GC-IMS and Sensory description, thereby establishing a link between typical VOCs and taste perceptions (). Notably, a study on Zanthoxylum motuoense employed HS-SPME-GC × GC-TOFMS combined with aroma analysis to establish the relationship between VOCs and sensory/emotional responses, creating a network map connecting chemical composition with sensory traits such as floral, citrus, and woody notes. This demonstrates how integrating GC-MS with sensory and network analysis can support traceability and origin classification by species or growing region ().
This study employs a combined chemometric and sensory approach to characterize the regional distinctiveness of Vietnamese black pepper. By integrating descriptive sensory analysis with GC–MS, we aimed to bridge the gap between objective chemical data and subjective sensory perception, thereby facilitating geographical indication (GI) authentication and traceability. The methodology involved a comparative analysis of samples from four key provinces (Dak Lak, Gia Lai, Dak Nong, and Quang Tri) to reveal aroma divergences attributed to specific pedoclimatic conditions. Multivariate data analysis was then applied to decipher the interplay between volatile biomarkers and sensory descriptors. The study’s outcomes underscore the feasibility of a Regional Sensory Lexicon, offering a robust model for establishing standardized sensory specifications. While initially applied to black pepper, this framework holds potential for the broader authentication of spices and herbs in the global market.
2 Materials and methods
2.1 Sample collection and material reagents
A total of twelve black pepper samples of the Vinh Linh cultivar were collected from four major cultivation regions in Vietnam: Quang Tri, Dak Lak, Dak Nong, and Gia Lai. This study focused exclusively on Vinh Linh as it is the predominant cultivar in Vietnam; concentrating on a single variety minimizes genetic variability, ensuring that observed differences primarily reflect environmental and agronomic factors. Specifically, to ensure regional representativeness despite the sample size (n = 3), each sample was prepared as a composite mixture from multiple farms within the districts. Thus, three composite samples from Quang Tri were obtained from Vinh Linh district; three samples from Dak Lak were collected from Buon Ma Thuot; three samples from Dak Nong were sourced from Dak Song district; and three samples from Gia Lai were collected from Dak Doa district. All samples were harvested at the same stage of ripeness and collected during the same harvest period within each region to minimize variability due to temporal factors. The selection of samples was based on a combination of factors, including cultivar type, plant age, geographic origin, cultivation practices, and harvest time. The sampling procedures adhered to the national standard TCVN 4889:1989 (equivalent to ISO 948:1980 - Spices and condiments - Sampling), ensuring consistency and reliability in the collection process ().
Each sample was properly labeled with comprehensive metadata, including information on the cultivar, plant age, cultivation method, farm location (with geographical coordinates), date of collection, sample weight, as well as the farmer’s name and contact information. Moisture content across the samples ranged from 10% to 13%, aligning with established quality standards for pepper. After collection, the samples were stored in zip-lock bags at room temperature (25 °C ± 2 °C) and placed in sealed, light-protected containers to maintain sample integrity prior to analysis.
2.2 Gas chromatography-mass spectrometry analysis
The volatile essential oil was extracted by steam distillation using a Clevenger apparatus according to TCVN 7039:2013(ISO 6571:2008), and subsequently analyzed by GC-MS following TCVN 9653:2013 (ISO 7609:1985) (; ). Approximately 50 g of sample was distilled with 500 mL of water for 5 h, and the volume of essential oil was measured using a graduated tube. The essential oil content was expressed in ml per 100 g of dry material. The collected oil was dried using anhydrous sodium sulfate (Na2SO4), then diluted with dichloromethane and analyzed using a GC-MS system (GC Trace 1,310, MS TSQ9000, Thermo Scientific) equipped with a DB-5MS capillary column (30 m × 0.25 mm × 0.25 μm). Operating conditions: initial temperature at 40 °C (held for 2 min), ramped at 8 °C/min to 250 °C, then at 15 °C/min to 300 °C (held for 2 min); electron ionization at 70 eV, ion source temperature at 250 °C, helium as carrier gas at a flow rate of 1.37 mL/min, splitless injection mode, and scan range of 40–500 amu. A standard mixture of saturated n-alkanes (C7–C30) dissolved in n-hexane was used for calculating retention indices and calibrating retention time. Quantification using the internal standard method was carried out by calculating the ratio between the peak area of the target compound and the average peak area of two adjacent alkanes (i.e., those eluting immediately before and after the compound of interest). The concentration of the compound was determined according to the following equation:
Where:
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C1 = 5 ppm is the concentration of the internal alkane standard (after 200-fold dilution),
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C2 is the concentration of the compound (after the same dilution),
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A1 is the average peak area of the two selected alkane standards, and
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A2 is the peak area of the compound.
The factor of 200 corresponds to the dilution factor applied to both the sample and the internal standard solution. The concentration of the compound is expressed in percentage (%). The conversion is based on the relation: 1 ppm = 10−4 (%). Each value is shown as the mean, n = 2.
2.3 Sensory analysis
2.3.1 Sample preparation
For sensory evaluation, 30 g of each black pepper sample were ground for 10 s using a laboratory grinder. Subsequently, 2.5 g of the ground sample were transferred into a 125 mL glass vial and covered with a watch glass to contain volatiles. The prepared samples were left to equilibrate at ambient conditions for 30 min prior to evaluation. Each sample was coded with a random three-digit number to ensure blind assessment.
2.3.2 Panelists
Sensory evaluation was conducted following the protocol outlined in TCVN 12389:2018 (ISO 8586:2023 - Selection and training of sensory assessors) (). A trained descriptive sensory panel consisting of 10 members was assembled. Panelists were recruited and screened according to criteria including health status, olfactory sensitivity, availability, long-term commitment, and motivation.
After the selection process, a panel of ten members participated in an intensive training program to develop the ability to perform reliable sensory evaluations of black pepper.
The development of the sensory lexicon began with three representative black pepper samples sourced from key cultivation regions in Vietnam: Quang Tri, Gia Lai, and Đak Nong. A five-point intensity scale (0 = not perceived, 1 = very weak, 5 = very strong) was used to assess aroma and flavor attributes. The preliminary list of sensory terms was compiled based on previous studies on the sensory characteristics of black pepper (; ; ). Descriptor refinement was carried out through multiple iterative sessions involving attribute screening, consensus on definitions, and selection of appropriate reference standards.
During each session, all samples were evaluated by the panel, followed by group discussions to refine and consolidate the sensory descriptors. Synonyms and ambiguous terms were eliminated, and standardized evaluation procedures were established. Once the descriptor list was finalized, the definitions and reference standards were agreed upon by panel consensus.
Subsequently, panelists underwent training to quantify sensory intensities using the finalized lexicon. Training activities included ranking exercises with standard references and intensity calibration using a five-point discrete scale. Anchor points on the scale were defined by quantitative reference standards, particularly for the “very strong” intensity level.
Panel training was conducted over 30 sessions, each lasting 2 hours, totaling approximately 60 h of instruction. The training focused on familiarization with the finalized sensory lexicon and calibration of intensity perception using reference materials. Exercises included ranking, rank-rating, and intensity rating tasks to ensure panel consistency and accuracy in sensory evaluation.
Panel proficiency was verified through a performance assessment conducted prior to formal evaluations. The final stage of training included a validation exercise, during which panelists evaluated four ground black pepper samples sourced from Quang Tri, Dak Nong, Dak Lak, and Gia Lai provinces. Each sample was assessed in duplicate using randomized three-digit codes and presented according to a Williams Latin square design to control for order and carryover effects. The consistency and reliability of panelists’ responses were analyzed to confirm the panel’s readiness for official sensory testing.
All training and subsequent descriptive sensory evaluations were carried out in the Sensory Laboratory at School of Chemistry and Life Sciences, Hanoi University of Science and Technology. The sensory room was maintained at a constant temperature of 20 °C throughout the study.
2.3.3 Quantitative Descriptive Analysis
Quantitative Descriptive Analysis (QDA) was employed to evaluate eleven predefined sensory attributes (Table 1). The generation, refinement, and final selection of these attributes were conducted in accordance with ISO 11035:1994, which outlines standardized procedures for the development of sensory terminology (). Each attribute was rated using a continuous line scale anchored with the descriptors “weak” (left) and “strong” (right). For data analysis purposes, the line scale was converted into a discrete 0–5 numerical scale, where 0 represented the absence of perception and 5 indicated the highest perceived intensity. For each pepper sample, each panelist conducted two independent replicate evaluations to ensure the reliability and consistency of the sensory data.
TABLE 1
| No. | Descriptor (English) | Definition | Descriptor (Vietnamese) | Reference standard | Intensity level (5) description |
|---|---|---|---|---|---|
| 1 | Fatty | A rich, creamy odor reminiscent of butter | Béo | Melted westgold unsalted butter | 1 g melted butter, rested 20 min in 100 mL vial |
| 2 | Lime | A sharp, acidic odor reminiscent of lime | Chanh xanh | Fresh lime peel | 1 g lime peel, rested 20 min in 100 mL vial |
| 3 | Salted dry apricot | A fermented odor reminiscent of fermented apricots | Ô mai | Tien Thinh canned soft apricots | 1 g apricot, rested 20 min in 100 mL vial |
| 4 | Grassy | A green odor reminiscent of freshly cut grass | Cỏ | Freshly cut grass | 1.5 g ground grass, rested 20 min in 100 mL vial |
| 5 | Citrus | A fresh, delicate odor with a balance of sourness and sweetness | Cam chanh | Australian orange peel | 1.5 g orange peel, rested 20 min in 100 mL vial |
| 6 | Minty | A refreshing, menthol-like odor reminiscent of mint | Bạc hà | Ricotta mint candy | 0.1 g candy, rested 10 min in 100 mL vial |
| 7 | Chinese herbs | A complex odor blending bitterness, earthiness, sweetness, and warmth | Thuốc bắc | Cam Xuyen Huong traditional herbal medicine | 0.05 g herb, rested 10 min in 100 mL vial |
| 8 | Pine-like | A resinous, woody odor reminiscent of pine trees | Thông | Pinene (Sigma-Aldrich) | 1.5 mL pinene in 100 mL pepper extract, rested 20 min |
| 9 | Pomelo flower | A floral odor reminiscent of pomelo blossoms | Hoa bưởi | Linalool (Sigma-Aldrich) | 1 mL linalool in 100 mL pepper extract, rested 20 min |
| 10 | Stale | A damp, earthy odor reminiscent of petrichor, soil, or mushrooms | Cũ | Wet rotten bark | |
| 11 | Floral | A delicate, sweet odor reminiscent of flower pollen | Hương hoa | Pollen |
List of sensory attributes evaluated in this study.
Sensory sessions were conducted in individual booths designed in accordance with ISO 8589:2007 guidelines, which ensure standardized conditions in terms of lighting, odor control, and minimal external distractions ().
During the evaluation, samples were presented to panelists one at a time. Prior to and following each assessment, panelists were instructed to rinse their olfactory receptors by inhaling filtered water. For each sample, the panelist gently slid the watch glass to create a small opening, positioned the vial approximately 1–2 cm from the nose, and inhaled for about 2 s. The vial was then resealed, and the perceived aroma attributes were recorded. Each sample was assessed up to three times to ensure consistency and accuracy. Between samples, panelists neutralized their sense of smell by inhaling from a separate cup containing filtered water.
2.4 Statistical analysis and software
Differences in key chemical and sensory components among black pepper samples from various cultivation regions were investigated using Principal Component Analysis (PCA). A one-way Analysis of Variance (ANOVA) was conducted to assess the effect of cultivation region on both GC-MS and sensory datasets. Statistical significance was determined at a threshold of p < 0.05. To visually compare the sensory profiles of samples across regions, radial plots were generated based on sensory attribute data. Furthermore, a Multiple Factor Analysis (MFA) was performed using the FactoMineR package in R, incorporating all variables that showed significant differences from both sensory and GC-MS datasets, in order to elucidate the relationships between these two variable groups. All statistical analyses and graphical visualizations were performed using the R statistical software environment (version 4.3.1).
3 Results
3.1 GC-MS of black pepper in different regions
A total of 117 volatile compounds were identified across all black pepper samples (Supplementary Material S1). Among these, 106 compounds were commonly detected in all samples, indicating a core volatile profile shared across different regions. To investigate how geographical origin influences the volatile composition of black pepper, Principal Component Analysis (PCA) was performed using the dataset comprising these 106 shared volatiles.
Principal Component Analysis (PCA) was performed on the dataset of 106 identified volatile compounds. Based on the contribution to the first two principal components, the top fifteen compounds with the highest total contributions were selected as the principal discriminating variables. These included: Isoledene, Cyclofenchene, (E)-β-Farnesene, β-Elemene, α-Bisabolol, β-Selinene, α-Pinene, β-Pinene, Nerolidol, Carvenone, m-Cymene, Thujone, 1-Phenyl-1-decanol, β-Panasinsene, α-Selinene, and Cubenene (Figure 1). Notably, these compounds have also been consistently reported in global studies investigating the volatile profiles of black pepper fruits (Piper nigrum L.), thereby confirming their significance as key constituents of the species’ aroma and chemical composition (; ).
FIGURE 1
Figure 2 presents the PCA score plot, which reveals a clear separation of samples based on their geographical origin, indicating that location-specific factors significantly shape the volatile compound profiles. The first two principal components (PC1 and PC2) explain 42.22% and 34.84% of the total variance, respectively, together accounting for 77.06% of the overall variability in the dataset.
FIGURE 2
Samples from Dak Nong, which are positioned on the negative side of PC1, are characterized by high concentrations of compounds such as β-myrcene, verbenol, germacrene D, (−)-myrtenol, δ-cubebene, α-muurolene, p-mentha-1,5,8-triene, humulene epoxide I, linalool, α-elemene, γ-terpinene, o-cymene, carveol, caryophyllene oxide, and 3-carene. In contrast, samples from Dak Lak, located on the strong positive side of PC2, are distinguished by elevated levels of p-menth-1-ene, α-cadinol, nerolidol, β-cadinene, β-elemene, and α-cubebene. Samples from Quang Tri, positioned on the positive side of PC1 and negative side of PC2, exhibit a distinct enrichment in a diverse set of volatiles including γ-neoclovene, spirodecene, (E)-β-ocimene, α-phellandrene dimer, 2-carene, (−)-aristolene, β-phellandrene, α-terpinene, trans-3-caren-2-ol, p-mentha-1,5-dien-8-ol, terpinolene/isoterpinolene, trans-calamenene, limonene, σ-cadinene, and β-panasinsene. Samples from Gia Lai, positioned near the origin of the PCA plot, likely represent a more balanced composition of volatile constituents without dominance from any particular compound group. Collectively, these findings confirm that volatile compound profiles obtained via GC-MS can effectively discriminate black pepper samples according to regional origin.
3.2 Sensory analysis of black pepper in differet regions
Quantitative Descriptive Analysis (QDA) enabled the development of a comprehensive sensory profile for the black pepper samples, effectively highlighting perceptible differences among them. To quantitatively describe the aroma characteristics of black pepper, it is essential to establish a well-defined sensory vocabulary accompanied by clear definitions and calibrated intensity scales. In this study, our trained sensory panel successfully developed a set of 11 aroma descriptors based on consensus, following structured training sessions, group discussions, and the elimination of ambiguous or infrequently perceived attributes (Table 1).
The finalized lexicon reflects the most relevant sensory characteristics of black pepper and provides a robust foundation for consistent sensory evaluation. Each descriptor was anchored with specific reference materials and intensity standards to ensure panel calibration and reproducibility. A radar plot was constructed based on the sensory data to visualize the aroma profiles of samples from different cultivation regions, as presented in Figure 3.
FIGURE 3
The black pepper samples from Quang Tri exhibited a distinctly strong and defining fatty aroma, setting them apart from samples originating in other cultivation regions (Figure 4). This dominant fatty note is typically associated with rich, creamy, and rounded aromatic characteristics, suggesting a deeper and more full-bodied sensory profile. The presence of this attribute may contribute to enhanced mouthfeel and flavor persistence, aligning with a perception of overall richness and complexity. Interestingly, the intensity of fresher, lighter notes such as: citrus, lime, and grassy, was notably subdued in these samples. This lack of bright top-note aromas may result in a more mellow but heavier flavor perception.
FIGURE 4
In contrast, black pepper from Gia Lai demonstrated an unexpectedly complex and vibrant sensory profile (Figure 4). Dominant attributes included: floral, citrus, lime, and particularly pomelo flower, all of which were detected at high intensities. These descriptors are typically associated with freshness, liveliness, and aromatic elegance, making them key differentiators of Gia Lai pepper compared to more conventional profiles. The relatively low intensity of the fatty note in these samples suggests a lighter mouthfeel but a more nuanced and layered aromatic experience. This flavor profile positions Gia Lai pepper as both distinctive and potentially more appealing for applications where freshness and floral character are desired.
Samples from Dak Nong were characterized by a well-balanced and mild sensory profile (Figure 4). Notably, floral and pomelo flower attributes were present but expressed more slightly than in Gia Lai samples, contributing to a gentle aromatic signature. Meanwhile, notes such as Chinese herbs-like and grassy were perceived at low intensity levels, suggesting a cleaner and less earthy profile compared to other regional peppers. This overall moderation across sensory dimensions may make Dak Nong pepper versatile and broadly acceptable for different culinary or industrial applications.
Pepper samples from Dak Lak, however, exhibited a more pronounced stale and grassy profile, with a secondary hint of pine-like character (Figure 4). These sensory markers contributed to a distinctly aged or potentially off-putting aroma, possibly indicative of post-harvest degradation, extended storage, or suboptimal processing conditions. Furthermore, these samples scored lower in pleasant aromatic attributes such as salted dry apricot and fatty, reducing their overall complexity and sensory appeal.
Among the 11 evaluated aroma attributes, 8 demonstrated statistically significant differences across the black pepper samples (p < 0.05; Table 2). This result indicates that black pepper originating from different geographical regions exhibits distinct aromatic profiles, which are likely shaped by environmental variables such as soil composition, climatic conditions, and agroecological factors. These regional disparities may influence the biosynthesis and accumulation of volatile compounds within the peppercorns, thereby contributing to unique sensory attributes. The findings provide a robust scientific foundation for differentiating black pepper based on its geographical origin, which has important implications for product authentication, terroir characterization, and quality assurance within the spice industry.
TABLE 2
| Attribute | Dak Lak | Đak Nông | Gia Lai | Quang Tri | P-value |
|---|---|---|---|---|---|
| Chinese herb like | 0.80 ± 1.15a | 0.13 ± 0.52a | 0.33 ± 0.72a | 0.80 ± 0.56a | 0.047 |
| Minty | 0.93 ± 1.03a | 0.93 ± 1.16a | 0.73 ± 1.28a | 0.73 ± 1.10a | 0.928 |
| Citrus | 1.07 ± 1.16a | 1.53 ± 1.30a | 1.40 ± 1.18a | 0.53 ± 1.06a | 0.106 |
| Lime | 1.60 ± 1.88a | 2.07 ± 1.91a | 2.07 ± 1.94a | 0.67 ± 1.18a | 0.108 |
| Salted dry apricot | 0.73 ± 1.10b | 2.07 ± 1.79ab | 2.07 ± 1.83ab | 2.33 ± 1.54a | 0.035 |
| Fatty | 0.00 ± 0.00c | 1.67 ± 1.59ab | 0.60 ± 1.18bc | 2.87 ± 1.96a | <0.001 |
| Grassy | 3.27 ± 1.44a | 1.07 ± 1.10b | 1.93 ± 1.79ab | 0.60 ± 1.12b | <0.001 |
| Floral | 1.27 ± 1.28a | 1.80 ± 1.32a | 2.47 ± 1.55a | 1.20 ± 1.32a | 0.051 |
| Pine like | 0.53 ± 1.13a | 0.13 ± 0.35a | 0.20 ± 0.41a | 0.13 ± 0.35a | 0.282 |
| Pomelo flower | 0.47 ± 1.13a | 0.47 ± 0.83a | 0.80 ± 1.42a | 0.27 ± 0.59a | 0.571 |
| Stale | 2.67 ± 1.76a | 1.00 ± 1.60b | 1.13 ± 1.46b | 0.20 ± 0.41b | <0.001 |
Average intensity scores of sensory attributes in samples from different geographical region.
Within the same row, means followed by the same letter are not significantly different according to Tukey’s HSD, test at the 5% significance level (p < 0.05). P-values were obtained from one-way ANOVA.
However, a noteworthy limitation of the sensory evaluation lies in the relatively high standard deviations observed across several aroma attributes, suggesting considerable variability in panelists’ assessments. For example, attributes like “Fatty” (e.g., 2.87 ± 1.96 in Quang Tri; 1.67 ± 1.59 in Đak Nong) and “Grassy” (e.g., 3.27 ± 1.44 in Dak Lak) displayed large error margins, reflecting inconsistent responses both within and between samples. This variability, compounded by the heterogeneous sensory profiles across regions, highlights the inherent subjectivity of sensory analysis.
3.3 The characteristic volatile compounds of black pepper from different regions were analyzed by GC-MS combined with sensory
Multiple Factor Analysis (MFA) was conducted to investigate the relationship between GC–MS and sensory attributes of black pepper samples. The first two principal dimensions explained 78.1% of the total variance, with Dim1 and Dim2 accounting for 42.2% and 35.9%, respectively.
Samples originating from QuangTri and DakLak exhibited a high degree of consistency between the two data blocks: sensory and GC-MS, as indicated by their close proximity in the individual factor map (Figure 5). In contrast, samples from Dak Nong and Gia Lai showed greater distances between sensory and GC-MS data points, reflecting notable discrepancies between sensory perception and chemical composition. This divergence highlights that for Dak Nong and Gia Lai samples, the chemical profile and sensory perception are less aligned than in other regions.
FIGURE 5
The group representation plot highlights the relative contributions of each data block to the main dimensions. GC-MS data contributed substantially to both Dim 1 and Dim 2, while sensory data showed a strong contribution to Dim 1 but only a moderate contribution to Dim 2. This suggests that GC-MS analysis more clearly distinguishes samples from Dak Nong and Gia Lai, whereas sensory data may better differentiate samples from Dak Lak and Quang Tri. Additionally, the high RV, coefficient (0.88 > 0.8) between sensory and GC-MS, indicates a strong correlation, implying a high degree of agreement between human sensory evaluation and instrumental chemical analysis (Table 3).
TABLE 3
| GCMS | Sensory | MFA | |
|---|---|---|---|
| GCMS | 1.00 | 0.88 | 0.97 |
| Sensory | 0.88 | 1.00 | 0.97 |
| MFA | 0.97 | 0.97 | 1.00 |
RV coefficients between GCMS, sensory, and MFA configurations.
While GC-MS quantifies volatile composition, it does not fully capture the complexity of olfactory perception. Therefore, examining the correlations between specific volatiles and sensory attributes (Figure 6) is essential to provide a holistic understanding of these aroma characteristics.
FIGURE 6
The sensory descriptor Floral demonstrated a robust positive correlation with both 3-Carene and γ-Terpinene. Specifically, 3-Carene is known for its lemon-like, citrusy, and sweet aroma, while γ-Terpinene has been reported to possess lemon, tropical, and lime-like odor characteristics (). While the chemical odor profiles of these compounds are not inherently associated with floral notes, their presence, particularly in combination and at specific concentrations, may contribute to and enhance the perception of floral attributes. The sensory attributes “Citrus” and “lime” were positively correlated with sabinene, a monoterpene known for its distinctive citrusy, spicy, and peppery aroma characteristics, as reported in FlavorDB2 (). The “Fatty” note showed strong associations with cyclofenchene, a compound exhibiting woody, amber, and dry olfactory qualities, as well as with terpineol, which contributes oily, minty, and woody nuances (). The descriptor “Salted dry apricot”, although somewhat isolated in multivariate space, exhibited a correlation with β-bisabolene, a sesquiterpene characterized by citrus, myrrh, and opoponax-like aromas (). The “Pine-like” attribute was closely linked to α-pinene, a compound well-documented for its resinous, sharp, warm, and fresh pine odor, along with guaiene, which imparts guaiacwood, spicy, sweet, and woody notes (). A strong association was observed between the “Grassy” descriptor and β-elemene, a compound recognized for its waxy, herbal, and fresh aroma profile. Additionally, nerolidol, typically perceived as woody, floral, and green, also contributed to this sensory dimension (). The “Minty” note was positively associated with α-terpineol, a compound known for its minty and slightly anise-like character (). The floral note “Pomelo flower” exhibited a positive association with camphor, a compound that adds a sharp, aromatic, and slightly cooling sensation to the aroma profile. The “Stale” attribute correlated with both β-selinene, which carries herbaceous qualities, and β-elemene, contributing again to waxy and herbal-fresh perceptions (). Finally, the “Chinese herb-like” attribute showed strong associations with α-farnesene and germacrene D-4-ol. The complex aroma of α-farnesene, described as citrusy, lime-like, neroli, herbal, myrrh, woody, and lavender-like, combined with the woody and spicy notes of germacrene D-4-ol, likely accounts for the multifaceted nature of this descriptor, frequently encountered in black pepper samples ().
4 Discussion
This study demonstrates the potential of integrating sensory and chemical analyses to enhance quality assessment and geographical traceability of spices, with a focus on Vietnamese black pepper. While such integrative approaches have been widely applied to commodities like wine, coffee, and tea, their application to spices, particularly for linking sensory and chemical data to support Geographical Indication (GI) certification and regional authentication, remains underexplored. To date, no studies have systematically combined sensory descriptors with GC-MS derived volatile profiles to establish a comprehensive framework for black pepper authentication.
The findings reveal distinct aroma profiles and volatile compound compositions among black pepper samples from four key Vietnamese cultivation regions. Dak Nong samples, enriched in compounds such as β-myrcene, linalool, and caryophyllene oxide, displayed a complex aroma dominated by woody, floral, and citrus notes (). In contrast, Dak Lak samples were characterized by higher levels of p-menth-1-ene, α-cadinol, nerolidol, and β-cadinene, contributing to warmer, earthier, and spicier olfactory qualities (). Quang Tri samples exhibited a distinct enrichment in a diverse set of volatiles, including γ-neoclovene, (E)-β-ocimene, limonene, and related compounds, associated with floral, citrusy, and resinous aromas (). Samples from Gia Lai presented a more balanced composition of volatiles, without dominance of any particular compound group. Multiple Factor Analysis (MFA) demonstrated a strong correlation between sensory attributes and volatile compounds (RV = 0.88), confirming a robust relationship between sensory perception and chemical composition.
By combining Quantitative Descriptive Analysis (QDA), GC-MS, and multivariate statistical methods, this study proposes a novel, transferable framework applicable not only to black pepper but also to other origin-dependent agri-food products, such as clove, star anise, turmeric, or cardamom. Unlike previous studies on Indonesian or Indian black pepper, which have primarily focused on quantifying essential oil yields or examining chemical constituents in isolation, this research provides a distinct contribution by establishing a direct statistical consensus between specific volatile biomarkers and human sensory perception. This methodology moves beyond simple chemotyping to offer a cohesive and interpretable approach that integrates sensory perception with chemical evidence, enabling both scientific characterization and the kind of narrative building essential for GI registration, consumer communication, and value-added marketing.
A notable limitation in the sensory data is the relatively high standard deviations for several aroma attributes, such as “Fatty” (e.g., 2.87 ± 1.96 in Quang Tri) and “Grassy” (e.g., 3.27 ± 1.44 in Dak Lak), indicating considerable variability in panelist responses. Such variation is not uncommon in descriptive sensory analysis, especially when evaluating complex natural products like black pepper that contain numerous overlapping volatile compounds. Unlike isolated aroma standards, natural samples often present multidimensional sensory inputs, making it more difficult for panelists to consistently distinguish specific notes. From a methodological perspective, the observed variation underscores a well-documented limitation of sensory analysis: while highly informative, it is inherently subjective and requires robust training, repeated calibration, and well-defined lexicons to reduce intra- and inter-panelist variability. Specifically, during retraining sessions, panelists repeatedly calibrated their perception of ‘Fatty’ (melted butter reference) and ‘Grassy’ (freshly cut grass reference) to strengthen discrimination and improve consistency. In addition to methodological factors, seasonal and agronomic variation, such as differences in harvest timing, post-harvest drying, or maturation stagemay also contribute to the observed sensory variability. Black pepper’s volatile profile is highly sensitive to environmental conditions and harvest maturity, which can influence the concentration and expression of key aroma compounds such as monoterpenes and sesquiterpenes. To improve consistency, future studies should consider expanding panel size, enhancing training with clearer descriptor definitions, incorporating complementary techniques such as odor activity values (OAVs) or GC-Olfactometry to better link key volatiles with perceptual relevance, and control or record these variables more precisely to isolate geographic effects from seasonal or technical noise.
Moreover, this work establishes a foundation for standardizing regional aroma profiles by proposing a sensory specification for Vietnamese black pepper. Such a specification could serve as a national benchmark, enhancing traceability and quality assurance across the supply chain. The proposed methodology is scalable and adaptable, with potential for global application through region-specific calibration to develop aroma benchmarks for various spices, thereby strengthening the role of sensory identity in international spice markets.
Despite the strong correlations observed via MFA, it is critical to acknowledge that high volatile abundance does not always translate to high sensory intensity. GC-MS quantifies concentration, but not the varying sensitivity of the human olfactory system. Future research endeavors should incorporate odor thresholds or odor activity values (OAVs) to facilitate the identification of aroma-active compounds, particularly those that may contribute significantly to regional flavor signatures.
5 Conclusion
This study provides strong evidence supporting the hypothesis that the sensory characteristics of black pepper are intrinsically linked to its basic chemical composition, with aroma profiles reflecting clear regional distinctions. Among the 11 sensory descriptors evaluated, 8 revealed significant differences between samples, demonstrating the effectiveness of integrating sensory and instrumental analyses to characterize and differentiate black pepper based on geographical origin. Quang Tri samples exhibited a rich, full-bodied profile dominated by a strong fatty note, associated with creamy and persistent flavors. In contrast, Gia Lai peppers were marked by vibrant floral and citrus notes, particularly pomelo flower, suggesting freshness and aromatic complexity. Dak Nong samples showed a mild and balanced profile with moderate floral and herbal attributes, while Dak Lak peppers were characterized by grassy and stale notes, possibly reflecting post-harvest or storage effects.
GC-MS analysis identified 117 volatile compounds, with 106 shared among all regions, establishing a core chemical fingerprint for black pepper. The strong correlation (RV coefficient = 0.88) between sensory descriptors and GC-MS data further confirms the relationship between perceptible aroma attributes and underlying chemical constituents. These findings validate the use of combined sensory-instrumental approaches for regional differentiation. In addition, they also provide a scientific foundation for traceability, Geographical Indication (GI) certification, and the development of standardized quality control frameworks that could be applied to other spice products beyond pepper.
Despite providing valuable insights, this study is subject to several limitations that should be acknowledged. Firstly, the analysis was restricted to black pepper samples obtained from four principal cultivation regions, which may not capture the full variability present across all pepper-growing areas in Vietnam. Secondly, the investigation focused primarily on aroma-related attributes and their association with GC-MS-derived volatile profiles, thereby overlooking other critical sensory dimensions such as taste and mouthfeel. Furthermore, the study emphasized geographical origin as the sole explanatory factor, without accounting for additional variables that may influence sensory and chemical characteristics, such as post-harvest processing techniques and storage conditions. These limitations underscore the need for more extensive, multidimensional research to achieve a comprehensive understanding of the sensory and chemical complexity of Vietnamese black pepper.
6 Future work
Several avenues for further research emerge from this study:
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Expansion of sample coverage: Including more growing regions and harvest seasons would improve the generalizability of the findings and allow investigation of year-to-year consistency.
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Integration of post-harvest factors: Drying method, storage conditions, and pepper maturity are known to influence aroma and should be systematically analyzed in future models.
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Cross-method validation: Complementary analytical techniques such as NIR spectroscopy, electronic nose, or LC-MS could be used alongside GC-MS to build multi-platform models for origin authentication.
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Consumer sensory studies: While trained panels are crucial for descriptive profiling, linking sensory attributes to consumer liking would help align scientific characterization with market relevance.
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International comparison: A broader study comparing black pepper from Vietnam, India, Indonesia, and Brazil would position Vietnamese products within a global sensory and chemical landscape, potentially highlighting competitive advantages.
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By addressing these directions, future research can refine origin authentication methods and elevate the role of sensory-chemical analysis in the development of high-value spice markets.
Statements
Data availability statement
The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.
Ethics statement
Ethical approval was not required for the studies involving humans because the study involved sensory (smell only) evaluation of black pepper samples by adult volunteers without any health risks. The participants were not from a vulnerable group and no sensitive personal data were collected. According to institutional guidelines, this type of research does not require ethical approval. The studies were conducted in accordance with the local legislation and institutional requirements. Written informed consent for participation was not required from the participants or the participant’s legal guardians/next of kin in accordance with the national legislation and institutional requirements because the study involved minimal risk and consisted solely of a smell-only sensory evaluation of black pepper by adult volunteers. Participation was entirely voluntary, and participants were informed verbally about the study’s purpose and procedures. According to institutional and national guidelines, written informed consent is not required for this type of non-invasive, low-risk sensory research.
Author contributions
TT: Methodology, Writing – original draft, Writing – review and editing. TL: Formal Analysis, Software, Writing – original draft, Writing – review and editing. NP: Software, Visualization, Writing – review and editing. QL: Conceptualization, Data curation, Writing – review and editing. QH: Methodology, Resources, Writing – review and editing. TC: Funding acquisition, Project administration, Writing – review and editing. HN: Conceptualization, Supervision, Validation, Writing – review and editing.
Funding
The author(s) declared that financial support was received for this work and/or its publication. This research is supported by the national-level science and technology project titled “Research and application of Blockchain technology to manage the production and consumption chain of Vietnamese pepper” (Project code: KC-4.0-24/19-25), funded by the Ministry of Science and Technology of Vietnam. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.
Conflict of interest
The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Generative AI statement
The author(s) declared that generative AI was used in the creation of this manuscript. During the preparation of this work the authors used ChatGPT 4-o in order to improve the readability and language of the manuscript. After using this tool/service, the authors reviewed and edited the content as needed and take full responsibility for the content of the published article.
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Supplementary material
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/frfst.2025.1672614/full#supplementary-material
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Summary
Keywords
black pepper, GC–MS, geographical indication, geographical origin, sensory descriptive analysis
Citation
Tran TTH, Le TP, Pham NH, Lai QD, Hoang QT, Cung TTQ and Nguyen HD (2026) Can you taste the place? Building regional sensory standards for black pepper with GC-MS and sensory perception. Front. Food Sci. Technol. 5:1672614. doi: 10.3389/frfst.2025.1672614
Received
24 July 2025
Revised
29 November 2025
Accepted
02 December 2025
Published
05 January 2026
Volume
5 - 2025
Edited by
Dandan Pu, Beijing Technology and Business University, China
Reviewed by
Julieta Domínguez-Soberanes, Universidad Panamericana, Mexico
Joana Ferreira, Escola Superior Agrária de Santarém, Instituto Politécnico de Santarém, Portugal
Qianhui Gu, Anhui Wangxiaolu Food Technology Co., Ltd, China
Updates
Copyright
© 2026 Tran, Le, Pham, Lai, Hoang, Cung and Nguyen.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Hoang Dzung Nguyen, dzung@hcmut.edu.vn
Disclaimer
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.