Vanilla may bring to mind a sweet, soft aroma. Yet when you smell a vanilla pod itself, impressions of fruit, wood, fermented materials, and more overlap. A 2025 study by Isabel Janid Perez-Viveros and colleagues investigated these differences in relation to traditional processing.
The researchers collected traditionally processed vanilla from four regions of Mexico and compared aroma characteristics, liking, moisture, and other properties at different stages of a process that alternates drying and “sweating.” Their aim was to describe the diverse aromas produced by methods passed down in each region, using both sensory vocabulary and measured values.
- The Postharvest Process That Develops a Sweet Aroma
- 62 People Describe and Score the Aroma of the Pods
- Different Expressions Around a Shared Vanilla Character
- Differences in Liking Became Clear in the 30-Cycle Samples
- A Well-Liked Aroma Does Not Necessarily Mean Optimal Moisture
- Describing Aroma Differences to Communicate Regional Knowledge
- Summary
- References
The Postharvest Process That Develops a Sweet Aroma
Freshly harvested vanilla does not develop its familiar aroma simply by being left as it is. Its aroma, color, and physical properties change through “curing,” which begins with heating the pods and includes sweating, sun-drying, conditioning, and maturation. Sweating means keeping the pods warm in boxes or similar containers between drying stages; it does not mean sweating in the human sense.
In this study, one cycle meant one day of sun exposure followed by placement in a sweating box, and samples were compared at 8 and 30 cycles. The study examined Vanilla planifolia from four regions: San José Acateno, Puebla (SJA); Jalpilla, San Luis Potosí (SLP); Cerro Quemado, Oaxaca (CQ); and Ejido Primero de Mayo, Veracruz (EPM). Commercial vanilla sold in Puebla was also included for comparison. This commercial control was not an experimental control made by processing the same raw material in a different way.
In Table 1 of the original paper, the regional abbreviations for Jalpilla and Cerro Quemado are reversed relative to the main text. The place names used here follow the methods text and the explanation accompanying Table 2.
62 People Describe and Score the Aroma of the Pods
The participants were 62 people aged 18–66. First, a list of 35 aroma terms was prepared based on a discussion among 10 of those participants who had sensory-evaluation experience, together with previous research. The terms went beyond sweet impressions to include caramel, honey, rum, wood, and fermented aromas.
In the main experiment, the 8-cycle and 30-cycle samples were evaluated on separate days. At each session, five samples in total, one from each of the four regions and the commercial control, were presented in numbered containers that concealed their identities. Participants smelled pods cut into pieces approximately 1 cm long and first rated their liking on a nine-point scale. They then selected applicable terms from the list of 35 and rated the intensity of the selected characteristics on a nine-point scale. This method is called RATA.
The researchers also measured moisture, protein, the extracted fraction corresponding to lipids, ash, and pH in the pods. This allowed them to examine aroma ratings alongside the physical and chemical condition of the food. The study did not separate and identify individual aroma compounds or measure the amount of vanillin.
Different Expressions Around a Shared Vanilla Character
At 8 cycles, the intensities of 20 of the 35 descriptors differed significantly between samples. At 30 cycles, that number was 13. This does not mean that the number of aromas fell from 35 to 13. Rather, when the same 35 terms were used, the number of attributes that statistically distinguished the samples changed.
For example, at 8 cycles, the Primero de Mayo sample had relatively strong impressions of dried fruit and rum, while a damp impression stood out in the Jalpilla sample. The Cerro Quemado sample at 30 cycles had a weaker caramel impression than many of the other samples and received a higher rating for the attribute describing a chemical smell.
At both stages, however, the intensity of the “vanilla” attribute did not differ significantly between samples. Even with a similar vanilla character, a different combination of surrounding aromas can change the overall impression. Using several descriptors made these differences apparent.
Differences in Liking Became Clear in the 30-Cycle Samples
At 8 cycles, the San José Acateno sample had a relatively high mean score of 6.02, but there were no statistically significant differences in liking between the samples, including the commercial control. A higher mean and a clearly demonstrated difference need to be considered separately.
At 30 cycles, differences in liking emerged. The San José Acateno sample had a mean score of 6.39, above the commercial control at 5.27 and the Cerro Quemado sample at 4.34. However, San José Acateno was not significantly preferred to the samples from every other region. These results also apply to the participants and samples studied; they cannot establish a ranking in which vanilla from that region always tastes best.
In an analysis mapping the aroma characteristics together, San José Acateno lay close to impressions of sweetness, fruit, honey, and nuts, and to higher liking, while Cerro Quemado lay close to chemical, dairy-like, and woody impressions. The authors interpret these aroma balances as relevant to acceptance. However, because they did not experimentally add or remove individual aromas, the findings cannot establish that increasing a honey aroma will always make a sample more appealing, or that a woody aroma will always make it less appealing.
A Well-Liked Aroma Does Not Necessarily Mean Optimal Moisture
The physical and chemical measurements also differed between samples, and moisture in the samples from all four regions was lower at 30 cycles than at 8 cycles. Moisture was particularly low in the 30-cycle San José Acateno sample, and the authors also draw attention to the risk of pods becoming brittle and breaking easily.
Moisture relates not only to keeping quality but also to the flexibility and sheen of the pods. In this study, a sample whose aroma was liked did not necessarily meet every desirable condition for the pods themselves. This is why the researchers measured moisture and other properties rather than simply scoring aroma.
Describing Aroma Differences to Communicate Regional Knowledge
In this comparison, different regions meant differences in raw material and growing conditions as well as processing methods. The same harvest was not randomly divided into groups that differed only in processing, so the observed differences cannot be isolated as effects of curing alone. The authors also acknowledge that other factors, including harvest timing, cultivation conditions, and region, may be involved.
Even so, comparing traditionally cured vanilla using a shared aroma vocabulary is meaningful. The authors suggest that this characterization could help communicate the value of regional products, improve processing, and preserve knowledge passed down in producing regions. They identify the analysis of volatile compounds by gas chromatography and other methods, linking perceived aromas with actual molecules, as a next step.
Summary
Vanilla from four regions of Mexico showed different expressions of fruit, rum, dampness, wood, and other impressions around a shared vanilla character. Differences in liking also appeared in the 30-cycle samples, but longer processing did not mean uniform improvement, nor did a place of origin alone determine preference.
The value of vanilla cannot be fully captured by one representative compound or the simple phrase “a sweet aroma.” Describing aromas shaped by both the background of the raw material and regional processing knowledge, through sensory vocabulary and the condition of the pods, is this study’s contribution toward communicating the differences in traditional vanilla and carrying its qualities forward.
References
Perez-Viveros, I. J., García-Barrón, S. E., Hernández-Rodríguez, B. E., Barrera-Rodríguez, A. I., Acero-Ortega, C. A., & Espejel-García, A. (2025). Influence of Traditional Vanilla Curing on Its Physicochemical Properties and Aromatic Profile. Foods, 14(9), 1652. DOI: 10.3390/foods14091652 / Full original article.
Original article: © 2025 by the authors. Licensee MDPI, Basel, Switzerland. CC BY 4.0.
