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Loop-Ultrasound-Assisted Extraction: An Efficient Approach for the Recovery of Bioactive Compounds from Oak Bark

Loop-Ultrasound-Assisted Extraction: An Efficient Approach for the Recovery of Bioactive Compounds from Oak Bark

Authors :
Ilaria Quaratesi
Ioan Calinescu
Vasile Lavric
Vittoria Ferrara
Elena Badea
Petre Chipurici
Elisa-Gabriela Dumbravă
Rodica-Roxana Constantinescu
Nicoleta Daniela Ignat
Ioana Popa
Source :
Agronomy, Vol 14, Iss 7, p 1452 (2024)
Publication Year :
2024
Publisher :
MDPI AG, 2024.

Abstract

Oak bark is a by-product known for its richness in polyphenols, with tanning substances being particularly interesting for their application in different fields. Vegetable tannins are mostly utilized in the leather sector, but are also widely used as adhesives, in cement plasticizers and for medical and agrochemical applications owing to their natural antimicrobial activity. This study aimed to develop a green and efficient pilot-scale technique for extracting polyphenols from oak bark by ultrasound-assisted extraction (UAE) using a modified Dual-Frequency Reactor (DFR). Different parameters, such as extraction time, temperature, and solvent type (water, sodium hydroxide or sodium sulfite and bisulfite solutions) were investigated for their influence on the total phenolic content (TPC) and the quantity of dry extract. Control experiments by conventional methods were also performed. UAE at 50 °C yielded the highest TPC and dry extract (confirmed by ANOVA analysis, p < 0.05) in just 10 min, suggesting that UAE can be considered an energy- and cost-effective alternative to conventional techniques. The most suitable solvent was found to be a 0.5% sodium hydroxide solution. The molecular profile of the extracts was assessed by FTIR-ATR spectroscopy, revealing typical signals of tannins in all extracts. Furthermore, antimicrobial activity tests demonstrated the complete absence of Gram-positive and Gram-negative bacteria in the extracts, ensuring the suitability of the product for different kinds of application.

Details

Language :
English
ISSN :
14071452 and 20734395
Volume :
14
Issue :
7
Database :
Directory of Open Access Journals
Journal :
Agronomy
Publication Type :
Academic Journal
Accession number :
edsdoj.7adfa0ac9b914ba0b265aa1f7a83fc3c
Document Type :
article
Full Text :
https://doi.org/10.3390/agronomy14071452