Abstract
Sambucus nigra flowers, known as elderberry flowers (EBF), are a plant tissue rich in polyphenolic phytochemicals with important bioactivities. However, there are few studies dealing with the production of polyphenol-containing EBF extracts. The objective of the investigation presented herein was the development of a high-performance green extraction methodology, to generate EBF extracts enriched in polyphenolic substances, using an efficient deep eutectic solvent, combined with ultrasonication pretreatment. The DES was composed of L-lactic acid (hydrogen bond donor—HBD) and glycine (hydrogen bond acceptor—HBA) and, after an initial screening to properly regulate HBD/HBA ratio, the extraction was optimized by deploying response surface methodology. Under the optimized conditions, which were DES/water (85% w/v), liquid-to-solid ratio 60 mL g−1, and stirring speed 200 rounds per minute, the extraction yield in total polyphenols amounted to 121.24 ± 8.77 mg gallic acid equivalents per g dry matter. The integration of ultrasonication prior to the batch stirred-tank extraction boosted polyphenol recovery of up to 174.73 ± 2.62 mg gallic acid equivalents per g dry matter. Liquid chromatography–mass spectrometry analysis showed that the richest EBF extract obtained was dominated by rutin, a di-p-coumaroylquic acid and chlorogenic acid.
Highlights
Edible flowers have been used in culinary practice since antiquity, serving as food ingredients and as agents of herbal folk medicine
elderberry flowers (EBF) were chosen as a plant material with peculiar polyphenolic composition, and samples were ultrasonication-pretreated before subjected to stirred-tank extraction with a highly efficient Deep eutectic solvents (DES), composed of L-lactic acid and glycine
Following examinations pointed mol out that stability of DES composed of lactic acid (LA) and Gly could be assured at RD/A
Summary
Edible flowers have been used in culinary practice since antiquity, serving as food ingredients and as agents of herbal folk medicine. Edible flowers may contain a wide variety of phytochemicals, mostly phenolic acids and flavonoids, and exhibit a multitude of biological effects, including antioxidant anti-inflammatory activity, as well as chemopreventive and neuroprotective properties [2]. Ultrasound-assisted extraction (UAE) is highly regarded as a sustainable means of recovering polyphenolic substances from plant material. It requires a rather moderate investment of solvent and energy, and it is easy to handle, safe, cost-effective, and reproducible. Additional information is necessary to further clarify this issue and bring out the usefulness of ultrasonication in sample pretreatment On this basis, EBF were chosen as a plant material with peculiar polyphenolic composition, and samples were ultrasonication-pretreated before subjected to stirred-tank extraction with a highly efficient DES, composed of L-lactic acid and glycine. The extracts obtained were examined regarding their polyphenolic load and antioxidant properties, and further extract evaluation was carried out by analyzing the polyphenolic profile with liquid chromatography–mass spectrometry
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