Obtaining Aromatic Extracts from Portuguese Thymus mastichina L. by Hydrodistillation and Supercritical Fluid Extraction with CO2 as Potential Flavouring Additives for Food Applications.

Júlia C Kessler,Yaidelin A Manrique,Vanessa A Vieira,Filipa Mandim,Isabel C F R Ferreira,Andreia Afonso,Lillian Barros,Alírio E Rodrigues,Madalena M Dias,Patrícia Ferreira,Isabel M Martins

doi:10.3390/molecules27030694

Júlia C Kessler, Yaidelin A Manrique + Show 9 more

Open Access

https://doi.org/10.3390/molecules27030694

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Abstract

Humans often respond to sensory impulses provided by aromas, and current trends have generated interest in natural sources of fragrances rather than the commonly used synthetic additives. For the first time, the resulting aroma of a selected culture of Thymus mastichina L. was studied as a potential food ingredient. In this context, dried (DR) and fresh (FR) samples were submitted to carbon dioxide (CO2) supercritical extraction (SFE) and hydrodistillation (HD) methods. The extracts were characterised according to their volatile composition by GC-MS, cytotoxicity against a non-tumour cell culture, and sensory attributes (odour threshold and olfactive descriptors). The most abundant aromas were quantified, and the analysis performed by GC-MS revealed an abundance of terpenoids such as thymol chemotype, followed by the precursors α-terpinene and p-cymene. DR and FR extracts (EX) obtained from SFE-CO2 show the highest content of thymol, achieving 52.7% and 72.5% of the isolated volatile fraction. The DR essential oil (EO) contained the highest amount of terpenoids, but it was also the most cytotoxic extract. In contrast, SFE-CO2 products showed the lowest cytotoxic potential. Regarding FR-OE, it had the lowest extraction yield and composition in aroma volatiles. Additionally, all samples were described as having green, fresh and floral sensory notes, with no significant statistical differences regarding the odour detection threshold (ODT) values. Finally, FR-EX of T. mastichina obtained by SFE-CO2 presented the most promising results regarding food application.

Highlights

Lipophilic volatile compounds play a notable influence on the olfactory marketing strategy in the food, cosmetic and fragrance industries
FR-EX obtained from SFE-CO2 showed the highest extraction yield (16.25 ± 0.23%), followed by DR-EX with 3.02 ± 0.39%, determined in DW (Dry Weight)
No odour detection threshold (ODT) results showed significant differences, and both SFE-CO2 products achieved the lowest toxicity among the lipophilic products

Summary

Introduction

Lipophilic volatile compounds play a notable influence on the olfactory marketing strategy in the food, cosmetic and fragrance industries. The thermal hydrolysis effect was observed in HD products by the formation of the p-cymene molecule, an aromatic monoterpene and precursor of the thymol and carvacrol (both isomers) compounds [6,7]. This reaction can occur rapidly through dehydrogenated and oxygenated γ-terpinene, respectively [1,8]. In addition to its safety, chemical stability, low cost and availability characteristics [10], CO2 can change its solvent capability by changing pressure and temperature, affecting the density of the fluid and the extraction efficiency [7,11]. Recognised as safe by the Food and Drug Administration [9], CO2 as a supercritical fluid is highly selective and favours the extraction of thermolabile bioactive compounds [7]

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