10-15-2022 4:34am

THE SECRET BEHIND VANILLA

The chemical secrets behind vanilla’s allure

From ice cream to lattes, vanilla is one of the most popular spices in the world. It’s also one of the most labor-intensive to produce, and shortcuts lead to a less tasty product. Today, scientists report a profile of 20 key chemicals found in vanilla bean extracts, including several previously unknown ones, that together create vanilla’s complex and enjoyable flavor. The work could help manufacturers and farmers develop better-tasting vanilla and improve quick-curing methods.

The researchers will present their results at the fall meeting of the American Chemical Society (ACS). ACS Fall 2022 is a hybrid meeting being held virtually and in-person Aug. 21–25, with on-demand access available Aug. 26–Sept. 9. The meeting features nearly 11,000 presentations on a wide range of science topics.

“Vanilla is the second-most expensive spice in the world,” says Diana Paola Forero-Arcila, Ph.D., who is presenting this work at the meeting. “One of the reasons it’s so expensive is because its flavor is developed during a curing process that takes up to nine months.”

Two shortcuts are currently used to get around this long, drawn-out curing process. One is to speed it up with quick-curing methods that attempt to recreate the luscious natural vanilla flavor in a fraction of the time. Another is to make artificial vanilla, familiar to consumers as a less pricey alternative to the real thing.

But these types of products fall flat in terms of flavor because they both focus on vanillin, Forero-Arcila explains. Quick curing attempts to maximize the amount of vanillin in the cured bean, whereas artificial vanilla contains only one flavoring agent — lab-made vanillin. Though vanillin is an important part of a vanilla bean’s flavor, the alternative products are missing many other flavor compounds that develop during the long, traditional curing process and that are essential to the distinctive vanilla taste. “It’s very important that we understand the complexity of vanilla’s flavor and try to identify the compounds that are behind that complexity,” says Forero-Arcila.

To capture that complexity, Forero-Arcila, who is a postdoc at The Ohio State University, used an approach called untargeted flavoromics to pinpoint which chemicals in vanilla bean extracts are the most important for the overall aroma and taste. The researchers first made extracts from 15 beans they sourced from various countries and that were cured differently. They then constructed a chemical profile of each type of bean and identified which compounds were present. To find out how people reacted to the extracts, the team asked more than 100 individuals to taste the samples and rate whether they liked or disliked the flavors.

By connecting the dots between the chemical profiles and the taste ratings, the researchers identified 20 compounds that are the main drivers behind whether a person likes the flavor of a vanilla extract. Of these compounds, some, like vanillin, were expected. “Some of the compounds we identified are well-known vanilla components; however, this is the first report of them impacting consumer acceptability,” says Forero-Arcila. And several compounds important for the flavor were completely unknown, says Devin Peterson, Ph.D., the project’s principal investigator. The researchers are still analyzing these novel vanilla compounds to determine the final structures, but they have observed that the compounds have phenolic and aglycone parts. They also identified some compounds present in the extracts that made people dislike the flavor. One example is anisaldehyde, which has a floral aroma. Forero-Arcila found that anisaldehyde is produced during the curing process from a previously unknown precursor.

With this new profile of compounds, the researchers plan to share what they’ve learned with others in the food and agricultural industries. They think that the profile could help producers and farmers identify high-quality, valuable extracts, and price those extracts to match their quality. “The more you understand about how to make the materials more valuable, the more that value should flow through the whole system,” says Peterson. In the future, vanilla breeding programs and curing methods could focus on selectively producing the optimum compound profile for good flavor in vanilla plants.

The researchers acknowledge support and funding from the Flavor Research and Education Center at The Ohio State University.

A recorded media briefing on this topic will be posted Wednesday, Aug. 24, by 10 a.m. Eastern time at www.acs.org/acsfall2022briefings.

ACS Fall 2022 will be a vaccination-required and mask-recommended event for all attendees, exhibitors, vendors and ACS staff who plan to participate in-person in Chicago. For detailed information about the requirement and all ACS safety measures, please visit the ACS website.

The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.

Title
Chemical drivers of vanilla flavor liking

Abstract
Vanilla owes its popularity to its highly desirable characteristic flavor and is an established staple ingredient all over the world. The characteristic vanilla flavor is developed during the “curing” of the beans, a process that is associated with the increase of hydrolytic enzymes that promote the production of flavor compounds. The traditional curing of vanilla beans is labor-intensive and can last up to nine months. Therefore, several quick curing methods have been developed; however, the flavor quality does not match those of traditionally cured beans. Hence, the complexity of vanilla flavor opens an opportunity for further discovery by identifying flavor actives to understand differences in the entire chemical composition and discover drivers of vanilla liking. This work adopted an untargeted flavoromics approach to characterize the chemical drivers of vanilla flavor liking. Fifteen beans of Vanilla planifolia species varying in origin and curing process were extracted and an untargeted GC/MS-QToF and LC/MS-QToF profiling along with the sensory evaluation including a consumer liking study (n = 122) and descriptive analysis (DA) were performed. Significant differences in the DA attributes and the consumer liking scores were reported among the 15 samples. Chemical drivers of vanilla flavor liking were investigated by modeling the chemical profiles and the corresponding liking scores by orthogonal partial least squares (OPLS) analysis with good fit and predictive ability (R2Y > 0.9 and Q2 > 0.8). The top predictive volatile and non-volatile compounds of vanilla flavor liking were selected based on their VIP predictive scores. All 20 predictive compounds were identified which included well-known compounds such as vanillin as well as novel compounds which include glycosides. Further sensory recombination testing demonstrated the sensory activity of the predictive compounds on liking. Understanding the markers that drive the liking of vanilla and their impact on flavor perception, will allow to control processes/formulation of products to improve and compete with high-quality vanilla goods.