Optimizing and Comparing Ultrasound- and Microwave-Assisted Extraction Methods Applied to the Extraction of Antioxidant Capsinoids in Peppers

Mercedes Vázquez-Espinosa,Gerardo F Barbero,Estrella Espada-Bellido,Carmelo G Barroso,Ana V González De Peredo,Miguel Palma,Marta Ferreiro-González

doi:10.3390/agronomy9100633

Mercedes Vázquez-Espinosa, Gerardo F Barbero + Show 5 more

Open Access

https://doi.org/10.3390/agronomy9100633

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Journal: Agronomy	Publication Date: Oct 12, 2019
Citations: 24	License type: CC BY 4.0

Affiliation: University of Cádiz

Abstract

Capsinoids are very similar antioxidant compounds to capsaicinoids, but less irritating, non-pungent and more palatable, and can thus be used in greater concentrations for food applications. To date, three capsinoids (capsiate, dihydrocapsiate, and nordihydrocapsiate) have been isolated from the pepper fruits. Due to its substantial commercial importance, it would be convenient to determine which pepper varieties have a richer content. Ultrasound- (UAE) and microwave- (MAE) assisted extraction have been implemented and analyzed using multivariate statistical methods. Firstly, different solvents were tested individually. The three best solvents were used in a set mixture design, where 42% methanol and 58% ethyl acetate were determined as the optimum combination for UAE, and 100% methanol for MAE. Subsequently, a Box–Behnken experimental design with four variables for both UAE and MAE (time, temperature, pH and sample mass:solvent volume “ratio”) was performed. The sample mass:solvent volume was the most influential variable in UAE; while for MAE no variable was any more influential than the others. Finally, both optimized extraction methods were successfully applied to different varieties of peppers. Besides, to demonstrate the efficiency of both extraction methods, a recovery study was performed. The results prove the potential of both techniques as highly adequate methods for the extraction of capsinoids from peppers.

Highlights

Peppers (Capsicum spp.) are plants from the Solanaceae family, originating in Central and SouthAmerican tropical and rainy areas [1]
A mixture design was performed in order to determine the optimal extraction solvent
The other two variables analyzed, temperature and pH, had almost no influence on the response. These results indicate that microwave-assisted extraction (MAE) is a dependable method for the extraction of this type of compounds of interest present in peppers, since it allows for extracting the highest possible amount of capsiate from the samples regardless of any variations of the factors that have been analyzed

Summary

Introduction

Peppers (Capsicum spp.) are plants from the Solanaceae family, originating in Central and SouthAmerican tropical and rainy areas [1]. The pepper is a well-known fruit due to its high content in bioactive compounds and its strong antioxidant capacity. Peppers are valued for their sensory attributes, and have a significant role in medical and pharmaceutical applications [3] This fruit is a great source of nutraceutical compounds such as capsaicinoids and capsinoids, bioactive components that support a healthy diet [4]. One of the main features of red peppers is their pungency, which is caused by a specific type of chemical compounds known as capsaicinoids [5] They have three clearly differentiated sections, the vanillyl group, the carboxamide group and the aliphatic chain [6].

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