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Direct Hot Solid-Liquid Extraction (DH-SLE): A High-Yield Greener Technique for Lipid Recovery from Coffee Beans
Daliane Cláudia de Faria1, Maria Eliana Lopes Ribeiro de Queiroz1, Fábio Junior Moreira Novaes1
1Departamento de Química, Universidade Federal de Viçosa, Campus Universitário, Avenida Peter Henry Rolfs, s/n, Viçosa 36570-900, MG, Brazil.
Plants (Basel, Switzerland)
|January 25, 2025
Summary
A new, sustainable method for determining lipid content in coffee beans offers an eco-friendly alternative to traditional Soxhlet extraction. This improved technique uses less solvent and energy, yielding comparable results safely and efficiently.
Area of Science:
- Analytical Chemistry
- Food Science
- Green Chemistry
Background:
- Soxhlet extraction, an AOAC-recommended method for lipid determination, utilizes large solvent volumes (n-hexane), high temperatures, and extended extraction times.
- The conventional Soxhlet method poses safety and environmental concerns due to solvent toxicity, substantial water consumption for cooling, and significant energy expenditure.
- There is a need for a safer, more sustainable, and efficient alternative for determining lipid content in plant-based food matrices like coffee beans.
Purpose of the Study:
- To develop and validate a sustainable, direct hot solid-liquid extraction procedure for determining lipid content in raw Arabica coffee beans.
- To compare the efficiency and sustainability of the developed method against the traditional Soxhlet extraction.
Main Methods:
- A 3^3 full factorial design was employed to optimize direct hot solid-liquid extractions in small-volume vials (4 mL).
- Key parameters investigated included ground coffee to solvent ratios, extraction temperatures, and extraction times.
- Lipid content was determined, and fatty acid composition was analyzed using Gas Chromatography-Mass Spectrometry (GC-MS) after transesterification.
Main Results:
- An optimized condition achieved an extractive yield statistically equivalent to the Soxhlet method.
- The alternative method requires significantly reduced solvent volume (2 mL vs. 300 mL) and sample mass (0.2 g vs. 30 g).
- The new procedure demonstrated reduced extraction time (1.5 h vs. 16 h), lower energy consumption, and eliminated the need for water cooling.
Conclusions:
- The developed direct hot solid-liquid extraction method is a sustainable and efficient alternative to Soxhlet extraction for determining lipid content in coffee beans.
- This greener approach minimizes solvent usage, waste generation, and energy requirements without compromising analytical accuracy or oil composition.
- The method offers significant advantages in terms of safety, environmental impact, and operational efficiency for food analysis laboratories.
