Flavour esters provide fruity and aromatic notes used in foods, beverages, fragrances and cosmetics. The study develops a reusable enzyme system for producing these compounds more efficiently.
Researchers develop a reusable enzyme system that rapidly produces fruity flavour esters, offering a cleaner route for food, beverage and cosmetics applications.
Flavour is one of the most important qualities of food and drink. A small amount of an aroma compound can shape how consumers perceive freshness, fruitiness, sweetness, richness or overall quality. These compounds are also important beyond food, including in beverages, fragrances and cosmetics.
Among these compounds, flavour esters are especially valuable. Many provide fruity, sweet or mellow notes. Ethyl caproate, for example, is associated with pineapple-like aroma and is an important flavour compound in strong-aroma spirits. In Chinese liquor, esters can account for a large share of the flavour substances that determine sensory quality and aroma characteristics.
A new study published in the Journal of Agricultural and Food Chemistry reports a faster and more reusable enzyme-based route for producing flavour esters. The international team developed a new immobilised enzyme catalyst, known as CALB@DMSN-C8, by attaching Candida antarctica lipase B to hydrophobic dendritic mesoporous silica nanospheres.
The study is significant because the flavour and fragrance industries need production methods that are efficient, selective, stable and more sustainable. Traditional fermentation can produce complex natural aromas, but it can be slow and difficult to control. Chemical synthesis can be faster, but may require harsher conditions and can lack the selectivity associated with enzyme catalysis. Enzymatic catalysis offers an attractive alternative because enzymes can work under milder conditions and provide high product selectivity.
However, free enzymes often suffer from poor stability and limited recyclability. This makes them difficult to use repeatedly in industrial processes. The new work addresses this challenge by immobilising the enzyme on a specially designed porous support.
The support material, dendritic mesoporous silica nanospheres, has a distinctive structure. Its radial pore channels, high porosity and accessible internal surface help reactants reach the enzyme more efficiently. In this study, the support was modified to become hydrophobic, which helped activate the lipase and improve its catalytic performance. The paper’s microscopy images show the spherical, wrinkled and radially porous structure of the silica nanospheres, while spectroscopy confirmed successful hydrophobic modification and enzyme immobilisation.
Under optimised conditions, the immobilised enzyme converted caproic acid to ethyl caproate at 98.5 ± 0.5% conversion in just 30 minutes. The reaction was carried out at 35 °C, using a caproic acid-to-ethanol molar ratio of 1:2 and 2% enzyme.
The catalyst also showed strong reusability. After 20 reuse cycles, the conversion rate for ethyl caproate decreased only slightly, from 96.1 ± 1.1% to 95.4 ± 1.6%. By comparison, the paper reports that Novozym 435 dropped to 31 ± 4.1% after five cycles under the tested conditions. This suggests that the new carrier helped prevent enzyme leakage and maintain the enzyme’s active structure.
This is important for industrial relevance. A catalyst that performs well once is useful scientifically, but a catalyst that can be recovered and reused many times is far more attractive for production. Reusability can reduce cost, waste and process complexity.
The system also showed broad applicability. The researchers used the immobilised enzyme to synthesise several flavour esters with high conversion rates, including ethyl valerate, ethyl caproate, ethyl heptanoate, ethyl octanoate, ethyl nonanoate, ethyl decanoate, ethyl laurate and ethyl palmitate. The reported conversion rates for many of these esters were above 98%. The system also produced isoamyl acetate, butyl butyrate and butyl caprylate, showing potential beyond one single ester product.
The study compared the new catalyst with earlier reported systems for enzymatic ethyl caproate production. The authors reported that CALB@DMSN-C8 achieved high conversion with strong catalytic efficiency, without relying on organic solvents such as toluene, cyclohexane or isooctane in the reaction system.
The findings could interest companies working in food flavourings, alcoholic beverages, fragrances, cosmetics and biocatalytic manufacturing. More broadly, the work contributes to the development of greener catalytic platforms that use enzymes instead of harsher chemical routes.
The authors also acknowledge that further work is needed before large-scale industrial use. Challenges include the preparation cost of mesoporous silica, the need to optimise reaction conditions, product inhibition, mass-transfer limitations and thermal management. Future development may involve combining the catalyst with continuous-flow reactors, such as packed-bed, fluidised-bed or microfluidic systems.
Even so, the study provides a strong platform for further collaboration. It brings together enzyme technology, porous materials, flavour chemistry, molecular simulation and process design. This makes it relevant not only to academic researchers, but also to companies looking for cleaner, faster and more controllable ways to produce high-value flavour and fragrance ingredients.
The work points towards a future where flavour compounds can be produced more efficiently using recyclable biocatalysts, helping manufacturers meet growing demand for cleaner and more sustainable production technologies.
Paper details
The paper, “Novel Immobilized Enzyme System Using Hydrophobic Dendritic Mesoporous Silica Nanospheres for Efficient Flavor Ester Production”, is published in Journal of Agricultural and Food Chemistry. DOI: 10.1021/acs.jafc.4c12029.
Authors and affiliations
The study was carried out by Run Liu, Qi Zhou, Yi Zhang, Yuanzhi Xu, Zhonghui Liu and Mingming Zheng from the Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, China; Kheng-Lim Goh from Newcastle University in Singapore; and Vladimir Zivkovic from Newcastle University, United Kingdom.
For further details, contact Associate Professor Yi Zhang at [email protected], or Associate Professor Kheng-Lim Goh at [email protected].
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