Influence of instant controlled pressure drop technology on the content of metabolites of interest in Elettaria cardamomum and Origanum majorana

Abstract

This doctoral research investigated Instant Controlled Pressure Drop (DIC) technology as a sustainable pretreatment to enhance the extraction of bioactive compounds from Elettaria cardamomum and Origanum majorana. DIC’s thermo- mechanical expansion improves solvent accessibility, mass transfer, and compound stability during subsequent extraction. In E. cardamomum, the results showed that coupling DIC with hydrodistillation increased the yield of essential oil (EO) and enhanced its antioxidant capacity. The essential oil yield of DIC-HD (140 ◦C and 30 s) resulted in 4.43% while it was 2.52% for control. Regarding the AOX of DIC-HD (165 ◦C and 30 s), it was 86% of DPPH inhibition and. 57.02% for control, and the Trolox equivalent antioxidant capacity of DIC-HD under the same conditions was 1.44 μMTE/g of essential oil (G. D. Teresa- Martínez et al., 2022).

On the other hand, when ultrasound-assisted extraction (UAE) was combined with DIC treatment, the essential oil yield increased remarkably compared to the control (22.53% vs. 15.6%) under DIC conditions of 140 °C for 30 s. The DIC 2 treatment (165 °C, 30 s) produced the highest DPPH discoloration (79.48%) and the best Trolox equivalent antioxidant capacity, reaching 0.60 μM TE/g was similar to the control. GC/MS analysis identified 28 volatile compounds, with α-terpinyl acetate, geranyl oleate, and oleic acid as the most abundant constituents. Overall, DIC treatment at 140 °C for 30 s combined with UAE granted high yield and also a desirable chemical profile. Furthermore, SEM imaging of untreated seeds revealed collapsed structures beneath the oil cell layer, which hindered extraction efficiency, but DIC-treated seeds exposed more porous structures (Castillo et al., 2023).

Regarding the fatty acid (FA) content of cardamom obtained by accelerated solvent extraction (ASE), the DIC process modifies the FA profile. The GC-MS analysis identified eight fatty acids. The composition of fatty acids is generally influenced directly by the combination of temperature (T) and treatment time (t). This applies to seven cardamom fatty acids —palmitic, stearic, oleic, elaidic, α-linoleic, α-linolenic, and arachidic acids— whose levels depend on both T and t. In contrast, only temperature had a significant effect on myristic acid (G. Teresa-Martínez, Rodriguez- Castillo, Alonzo-Macías, Téllez-Pérez, & Cardador-Martínez, 2025). Regarding the essential oil (EO) profile, limonene was the most abundant compound, reaching 40.54% under the DIC 8 treatment (122 °C, 19 s). It was followed by eucalyptol, which showed its highest level—24.31%—under DIC 9 (122 °C, 41 s). The composition of these key constituents appears to be shaped by the 7 specific DIC processing conditions. For compounds such as eucalyptol, 3-carene, p- menth-1-en-4-ol, linalyl valerate, and α-citral, both treatment factors, time and temperature, are essential. In contrast, the quantity of β-selinene, p-mentha-1,4- dien-7-ol, α-terpineol, and geraniol is significantly influenced by only one of these factors. Lastly, for O. majorana, DIC combined with UAE, ASE, and maceration enhanced thymol and carvacrol recovery compared with untreated samples, suggesting the possibility of selectively modulating the volatile composition while preserving these key compounds.

Overall, DIC proved to be a versatile and energy-efficient pretreatment, capable of improving yield, chemical integrity, and functional quality across multiple extraction systems, thereby demonstrating its potential for the development of high-value natural-origin products in the food and nutraceutical industries.

The fatty acid composition induced by instant controlled pressure drop technology (G. Teresa-Martínez et al., 2025), explored the effect of DIC parameters on fatty- acid distribution using GC–MS profiling, revealing pressure–time interactions as critical determinants of lipid composition.

On the fourth paper, Modulation of the volatile profile of cardamom (Elettaria cardamomum) essential oil by non-thermal Instant Controlled Pressure Drop (DIC) Technology: A Novel Approach in Food Processing (under revision, 2025).

Complementing the preceding works, this study focused on the chemical composition of DIC-pretreated cardamom oils. GC–MS analysis showing that DIC modulated the abundance of key volatiles, notably increasing their yield in some cases while preserving the overall monoterpene and monoterpenoid balance. The findings suggest that DIC can act as a selective, energy-efficient tool to fine-tune EOs composition without compromising stability.

Finally, the ongoing study, "Thymol and Carvacrol Recovery and Antioxidant Properties of Origanum majorana Extracts Pretreated by Instant Controlled Pressure Drop Technology Coupled with Different Extraction Techniques," investigates the recovery of phenolic monoterpenes under diverse extraction environments.

Together, these works demonstrate that DIC technology can serve as a universal pretreatment platform for enhancing the extraction performance of various compounds. The synergy between mechanical expansion and selective extraction not only boosts yield but also preserves functional quality, offering a scalable route for producing high-value natural extracts for food, cosmetic, and pharmaceutical applications.