Achieving Vanilla Flavor through Bioeconomy

Vanilla is a spice extracted from several species of the orchid genus Vanilla. Their green capsules, which can be up to 30 centimetres long and are often referred to colloquially as pods, are first browned in ovens heated to 60 degrees Celsius, dried and stored in sealed baskets for fermentation. 

The most important species is Vanilla planifolia, which accounts for 95% of the world's vanilla cultivation. The original home of vanilla is Mexico and Central America, where even the Aztecs used the spice, particularly as a cocoa additive. 

Growing regions on islands in the Indian Ocean

Today, cultivation is mainly concentrated on Madagascar and Réunion as well as other islands in the Indian Ocean. Réunion's former name Île Bourbon gave the bourbon vanilla its name. There is also Mexican vanilla, Tahitian vanilla and Guadeloupe vanilla. The latter is primarily used to produce fragrances for the perfume industry, while the other varieties are primarily used as flavorings. 

If the start-up Dutch Vanilla Growers has its way, another region could grow vanilla on a large scale in the future: the Netherlands, albeit in a greenhouse. Research and development took place at Wageningen University. In 2017, the first cultivation began near Rotterdam on 6,000 square meters. In 2022, the company Koppert Cress marketed vanilla from the greenhouse for the first time in the Netherlands. 

Painstakingly pollinated by hand

Hummingbirds are the natural pollinators of vanilla orchids. Since they are absent in most growing regions, the cultivation of vanilla involves a great deal of manual labor. On top of this, there is only a time window of around twelve hours for pollination before the flowers wither. The next chance to pollinate is not until a year later. This, combined with the eight-month fermentation process and fluctuating harvests, leads to a high value of vanilla, but also to highly volatile prices on the global market, ranging from 40 US dollars per kilo in 2005 to more than 700 US dollars in 2019. 

Demand cannot be met from natural sources 

The fact that vanillin, the flavoring agent in vanilla, can be chemically synthesized since 1874 has not changed its value. At around 37,000 tons per year, demand is so high that vanillin from natural vanilla cultivation cannot even come close to meeting it. A good 90% of the vanillin used worldwide therefore comes from synthetic production; some sources, such as the industry magazine Food Ingredients First, even put the figure at 99%. 

According to forecasts, the market will continue to grow, driven by products such as ice cream, chocolate, beverages and baked goods. According to the Centre for the Promotion of Imports from developing countries (CBI), which is part of the Dutch Ministry of Foreign Affairs, the vanilla-flavored alcoholic beverage segment alone grew by 44% in Europe between 2018 and 2022. 

Germany is the third largest importer in the world 

In 2021, Germany imported 695 tons of vanilla, making it the third largest importer in the world. Almost two thirds of imports came directly from the producing countries. 450 tons of vanilla were consumed in the country, the rest was exported in the form of food ingredients or consumer products. In Europe, Germany is the most important market for vanilla alongside France and the Netherlands. 

75% of EU-wide imports and thus a third of all global imports end up in these three countries. Of global imports, 42% go to the USA. Broken down into individual companies, Coca-Cola stands out: the company sources a tenth of the world's vanilla production. Experts believe that Dr. Oetker is the largest vanilla processor in Germany. 

Weather is a risk in cultivation 

However, the high and growing demand poses a number of challenges for cultivation. In addition to pollination by hand, these include extreme weather conditions. The growing regions are repeatedly hit by tropical cyclones. In recent years, Madagascar, the main vanilla-growing region, has also suffered from repeated droughts. The high prices in 2017 were due to a season characterized by drought, which was followed by a cyclone shortly before the harvest, destroying an additional fifth of the crop. Further poor harvests in subsequent years led to vanilla temporarily rising in price to the value of genuine silver.   

This also led to more cases of fraud, in which natural vanillin was diluted with synthetic vanillin or other additives. However, a "stable isotope analysis" can be used to check the quality of vanilla as well as its origin. 

Another issue in vanilla cultivation is poverty wages. Vanilla farmers are often paid less than ten euros per kilogram of vanilla. However, more and more major buyers are making a commitment to support vanilla producers in producing in a socially and ecologically sustainable way. Transparency in the supply chain is also becoming increasingly important. On the other hand, the synthetic production of vanillin is growing due to the difficulties in cultivation. 

The demand for natural vanilla remains high. As with the cultivation of cocoa, there are problems such as poor pay, child labor, corruption and robberies. It is therefore an important goal to make vanilla cultivation more sustainable. Established certificates such as the Fairtrade seal and the EU organic seal contribute to this. 

Sustainable working conditions 

As more and more consumers expect sustainability, some food companies have joined forces to promote ethical and sustainable vanilla cultivation. The best-known example is the Livelihoods Fund for Family Farming (Livelihoods 3F). Its aims are to preserve Madagascar's unique natural environment, improve people's food security, triple farmers' incomes and ultimately ensure a high quality of vanilla. The founding partners were Danone, Firmenich, Mars and Veolia. 

Fragrance and flavoring manufacturer Symrise also seeks to promote better working conditions and consistently high product quality. Since 2018, the company has been working with around 7,000 small farmers to investigate different cultivation methods - from agroforests to shaded greenhouses. They jointly analyze soil structure, optimal irrigation and other factors and disseminate this knowledge among the smallholders. If the farmers produce particularly high-quality vanilla, they receive a bonus payment for the effort involved. 

Conversion to organic farming

But it is not only the working and living conditions that need to improve. In newly marketed vanilla-based products, one third of the vanilla already comes from organic farming. However, the conversion of conventional farms often means that yields per hectare fall. For the farmers, this is compensated for by the higher price. Even so, this reduces the volume of vanilla on the world market. 

A project by the universities of Göttingen, Marburg and Hohenheim could help solve the problem of scarce supply. In 2022, the researchers demonstrated that it is possible to establish vanilla plantations on fallow land and achieve the same yield as on plantations in existing old-growth forests. Cultivation in existing forests is often associated with partial clearing and also reduces the biodiversity there. In contrast, agroforestry systems established on fallow land for vanilla cultivation increase the number of species compared to former fallow land, the study found. Fallow land is often kept open by slash-and-burn methods in order to grow rice. 

Agroforestry systems are doubly useful for vanilla cultivation, as Göttingen researchers were able to show in another study: In addition to the shade that is important for the orchids, they also provide a higher number of predatory animals such as ants, grasshoppers and birds. These animals feed on insects that damage the vanilla plant and thus serve as a natural pest control. The fewer trees there were in a landscape, the smaller this effect was. 

Vanilla cultivation in high-tech greenhouses

Another research approach is to take vanilla cultivation out of regions that are ecologically valuable or prone to yield losses. This usually requires indoor farming. So far, it is mainly the Netherlands that has tried its hand at greenhouse cultivation outside the tropics. Furthermore, an investor in Australia is pursuing this ambitious goal. The first harvest from the 26 domes near Sydney was in 2021. 

In Germany, for example, the SustainVanil research project led by Osnabrück University of Applied Sciences is working towards this goal. The project is part of the New Food Systems innovation area, which is funded by the Federal Ministry of Education and Research (BMBF). 

The researchers are studying the plant physiological growth and development processes of vanilla and how its ingredients change during these processes. The project is also testing new biological plant protection measures. Ultimately, the knowledge gained is intended not only to form the basis for vanilla cultivation in Germany, but also to help optimize cultivation in Madagascar. 

The indoor farming of vanilla can be trialed directly at Osnabrück University of Applied Sciences since 2022. Based on the principle of vertical farming, there are six chambers for growing vegetables and spices. The chambers make it possible to precisely control and thus optimize environmental factors such as light, temperature, CO2 content, water and nutrient supply. This could make it possible to produce vanilla consistently and with stable quality all year round at almost any location in the world. 

Synthetic vanillin is not only used in inexpensive foods and in the production of fragrances in the cosmetics industry. There is also a third, lesser-known area of application: the pharmaceutical industry uses tens of thousands of tons every year to produce medicines. Here, the purity of the compound is particularly important, as is reliable sourcing. 

Vanillin from cloves and guaiac trees 

The first synthetic vanillin, produced in 1874 by the German chemists Gustav Haarmann and Ferdinand Tiemann, was based on coniferin, a glucoside of coniferyl alcohol. The latter is obtained from the sap of young conifers. Commercially, however, eugenol was initially used for the chemical production of vanillin. Eugenol is a phenylpropanoid that occurs in plant oils, especially clove oil. The compound is oxidized to vanillin by potassium permanganate or ozone via the intermediate stage isoeugenol. 

The production of vanillin from guaiacol also has a long history. It was first achieved in 1876 by the German chemist Karl Reimer. Guaiacol, a secondary plant substance of the guaiac tree, was converted to vanillin using chloroform. Since then, further processes have been developed to produce vanillin from guaiacol. In practice, guaiacol is often derived from petrochemical sources. 

Lignin as a resource

Besides extraction from guaiacol, the most important chemically synthetic method today is synthesis from lignosulfonic acid. This compound is a waste product from cellulose production. Under increased pressure and temperature, the acid reacts by adding oxidants and alkalis to form vanillin, among other things, which then has to be extracted and purified. Depending on the type of wood from which the lignin originates, the yields are between 7 and 25 %. In contrast to the synthesis from guaiacol, a by-product is also produced, acetovanillon, which gives the lignin-based vanilla aroma a broad flavor profile. 

A team led by Siegfried Waldvogel from Johannes Gutenberg University Mainz has developed a particularly sustainable lignin-based process that does not produce any toxic waste materials and does not require copper as a catalyst. An electrolysis cell with nickel electrodes is used, and the lignin is heated to 160 degrees Celsius in a caustic soda solution. The electrolysis then oxidizes the lignin and vanillin is formed. The flavoring produced in this way can be declared as natural vanillin. The most exciting aspect: the yield was initially around four percent of the weight of the lignin used. 

Theoretically, this process could cover the global demand for vanillin. In spring 2023, the team then reported on a further development in which a sustainable oxidizing agent, a peroxodicarbonate solution, is used. The researchers also succeeded in increasing the yield to 6.2 percent by weight. Last but not least, the carbonate used is also used in cellulose plants, making the new process ideal for combining with a biorefinery. 

Alongside methanol, vanillin is the most economically significant flavoring agent. Accordingly, it was of great interest for biotechnology to develop alternative production processes to chemical synthesis. In general, microbial cell factories offer a number of advantages: The organisms work under mild reaction conditions, which reduces energy costs. 

In addition, the microorganisms can be fed with renewable raw materials, often even residual materials, replacing the fossil feedstocks often used in the chemical industry. Last but not least, microorganisms can use their enzymes to produce structurally highly complex compounds, some of which are still impossible to synthesize chemically. 

Since the mid-1990s, biotechnological processes have therefore been used to produce vanillin on an industrially relevant scale. In addition to ferulic acids, the various processes also rely on raw materials that are already known from chemical synthesis: Eugenol, isoeugenol and lignin. Several cell factories, including plant cells, were tried to produce vanillin, but most of them proved to be uneconomical. 

This was due to a number of challenges: Firstly, both some of the starting materials and the vanillin itself are often toxic to the organisms producing it. In addition, undesirable by-products are formed during vanillin metabolism, and the starting materials are not only used by the cells for vanillin - both of which reduce the yield. Last but not least, in experimental projects for the production of vanillin, there were large losses during the purification of the product. 

From ferulic acid to vanillin 

In the end, one process proved successful: the production of vanillin from ferulic acid in a single fermentation step. Ferulic acid is found in various plants, including grasses such as wheat and barley, and is involved in the natural formation of lignin in the cell walls. 

For vanillin production, most companies opt for rice husks, which are a by-product of rice processing. Biotechnological processes with bacteria of the genus Amycolatopsis achieve particularly high yields. However, processes have also been developed with Escherichia coli, Pseudomonas putida, Saccharomyces cerevisiae and Streptomyces setonii, to name but a few. 

The established synthesis in Amycolatopsis bacteria proceeds in such a way that a thioester is first formed from the ferulic acid by the ferulyo-CoA synthetase and coenzyme A. The enoyl-CoA synthetase then cleaves the thioester. Then the enoyl-CoA hydratase/aldolase cleaves acetyl-CoA and vanillin is formed. The bacterial metabolism thus differs from that of the plant. There, vanillin synthase catalyzes the conversion of ferulic acid to vanillin in a single step. 

In spring 2023, Chinese researchers presented an Amycolatopsis strain in which two synthesis pathways for by-products of vanillin metabolism were switched off by means of genome editing. This doubled the vanillin yield to around 20 grams per liter and reduced the unwanted by-product vanillic acid from 2.45 to 0.15 grams per liter. A team from the University of Münster also reported a similarly high vanillin yield in genetically optimized Amycolatopsis bacteria in 2016. 

Researchers at the University of Münster have also identified a bacterium of the genus Pseudomonas that converts eugenol to vanillin. Unlike many bacteria, the strain used can fully convert the antibacterial eugenol. The process proceeds via coniferyl alcohol and coniferyl aldehyde to ferulic acid, which then becomes vanillin. However, the bacterium naturally processes vanillin further to vanillic acid and finally protocatechuic acid. 

Plant constituents from ferulic acids 

A team from Leibniz IBP and the University of Halle-Wittenberg has succeeded in isolating the enzymes required for ferulic acid synthesis and expressing them in E. coli bacteria. This provides the first process for the biotechnological production of ferulic acid. From 2020 to 2023, the partners at the Fraunhofer CBP optimized the bioprocess in the FeruBase project to produce ferulic acids as a precursor for high-quality flavorings such as vanillin and other health-promoting substances. The BMBF has supported the project with 1.5 million euros as part of the funding measure "Tailor-made bio-based ingredients for a competitive bioeconomy". A follow-up project, FeruChain, is now underway to further optimize the process until 2026. 

On the way to vanilla flavor, a de novo synthesis starting from glucose has been described in biotechnology since 2009, which has been implemented, among others, in E. coli, S. cerevisiae, and S. pombe. To counteract the toxicity of vanillin, it is first glucosylated to glucovanillin and only converted back to vanillin in a subsequent step. 

PET upcycling 

Researchers from Scotland have developed an upcycling approach with an unusual raw material. A team from the University of Edinburgh led by Joanna Sadler and Stephen Wallace uses old PET drinks bottles as a starting material. The polyethylene terephthalate is first broken down into terephthalic acid. 

E. coli bacteria then convert the acid into vanillin. The conversion rate has already reached 79%. This approach would not only contribute to the circular economy, but would also reduce the economic disadvantage that biotechnological processes still have compared to the chemical synthesis of vanillin. Compared to natural cultivation, they are already cheaper.